24,085 results on '"PORE water pressure"'
Search Results
2. Subgrade Fluidization Under Cyclic Loading and Preventive Measure by Geosynthetics
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Arivalagan, Joseph, Rujikiatkamjorn, Cholachat, Indraratna, Buddhima, Warwick, Andy, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Cui, Zhen-Dong, Series Editor, Lu, Xinzheng, Series Editor, Rujikiatkamjorn, Cholachat, editor, Xue, Jianfeng, editor, and Indraratna, Buddhima, editor
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- 2025
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3. One‐dimensional consolidation analysis of layered soil with exponential flow under continuous drainage boundary.
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Zhang, Yi, Wang, Jia, Zong, Mengfan, Wu, Wenbing, Cai, Siyu, Zong, Zhongling, Mei, Guoxiong, and Wang, Chenming
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PORE water pressure , *SOIL consolidation , *SOLIFLUCTION , *SOIL solutions , *SOIL testing - Abstract
To comprehensively consider the influence of boundary conditions, non‐Darcy flow, load forms, and soil stratification on soil consolidation, a one‐dimensional soil consolidation equation is established. By subdividing the soil layer and employing time discretization, the nonlinear consolidation equation is linearized, resulting in an analytical solution for layered soil foundation at any given time. Subsequently, an iterative approach for time solution is employed to obtain a semi‐analytical solution. The correctness of the solution is verified by comparison with solutions based on Darcy's flow and the semi‐analytical method under traditional drainage boundary conditions. Subsequently, the influence of interface parameters, loading conditions, flow index, and other factors on consolidation characteristics is analyzed. The results indicate that higher interface parameter values for continuous drainage boundaries correspond to faster average consolidation rates for stratified soil foundations, while these parameters have little effect on the time required for complete consolidation of the soil layers. Improved boundary drainage performance amplifies the influence of exponential flow on pore water pressure and average consolidation degree. Conversely, poor boundary drainage performance diminishes the impact of exponential flow on soil consolidation, rendering it negligible. Moreover, faster loading rates accentuate the influence of the flow index on the average consolidation degree defined by pore pressure. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Superposition‐based concurrent multiscale approaches for porodynamics.
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Sun, Wei, Zhang, Jian‐Min, Fish, Jacob, and Wang, Rui
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SOIL liquefaction , *PORE water pressure , *SHEAR strain , *FINITE element method , *HYDRAULIC fracturing - Abstract
The current study presents superposition‐based concurrent multiscale approaches for porodynamics, capable of capturing related physical phenomena, such as soil liquefaction and dynamic hydraulic fracture branching, across different spatial length scales. Two scenarios are considered: superposition of finite element discretizations with varying mesh densities, and superposition of peridynamics (PD) and finite element method (FEM) to handle discontinuities like strain localization and cracks. The approach decomposes the acceleration and the rate of change in pore water pressure into subdomain solutions approximated by different models, allowing high‐fidelity models to be used locally in regions of interest, such as crack tips or shear bands, without neglecting the far‐field influence represented by low‐fidelity models. The coupled stiffness, mass, compressibility, permeability, and damping matrices were derived based on the superposition‐based current multiscale framework. The proposed FEM‐FEM porodynamic coupling approach was validated against analytical or numerical solutions for one‐ and two‐dimensional dynamic consolidation problems. The PD‐FEM porodynamic coupling model was applied to scenarios like soil liquefaction‐induced shear strain accumulation near a low‐permeability interlayer in a layered deposit and dynamic hydraulic fracturing branching. It has been shown that the coupled porodynamic model offers modeling flexibility and efficiency by taking advantage of FEM in modeling complex domains and the PD ability to resolve discontinuities. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Rainfall-induced Guilong landslide-mudflow in a terraced field of southwestern China on 22 June 2022.
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Wang, Fawu, Zhang, Bo, Yan, Kongming, Liu, Weichao, and Gao, Jie
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PORE water pressure , *SOIL permeability , *RAINFALL , *AGRICULTURE , *FIELD research , *LANDSLIDES - Abstract
Extreme rainfall events, within the context of climate change, pose a heightened risk of geohazards to mountainous regions. On 22 June 2022, a rainstorm-induced landslide-mudflow occurred in a terraced field in Longsheng County, Guangxi Zhuang Autonomous Region, China. The disaster began as a rotational slide, and mobilized into a mudflow with high mobility and long runout, causing significant damage to the local community. This event served as a wake-up call not only for the safety of mountain settlements, but also for the protection of terraced fields as Globally Important Agricultural Heritage Systems. To elucidate the trigger and mudflow mobilization of the event, field investigation, hydrological and agricultural analyses, and laboratory tests were conducted. It was found that the persistent and record-breaking rainfall directly triggered the disaster by increasing pore water pressure. The transition from paddy terraces to dry terraces was deduced to have contributed to a lack of maintenance in the terrace drainage system, thereby heightening the likelihood of landslides. The mudflow mobilization was attributed to excess pore water pressure generated by soil contraction and an undrained condition maintained by low permeability soil. Soil experiencing sliding may be more susceptible to shear contraction, consequently resulting in long-runout motion. Under conditions of increasing extreme rainfall, greater attention needs to be paid to geo-disaster prevention and terraced field protection in mountainous regions. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Integrated effects of inherent and induced anisotropy on reliquefaction resistance of Toyoura sand with different strain histories.
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Fardad Amini, Pedram and Wang, Gang
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SHEAR strain , *PORE water pressure , *CYCLIC loads , *SOIL testing , *SOIL structure - Abstract
Recent earthquakes in New Zealand and Japan showed that pre-shaking histories significantly affected the reliquefaction resistance of soils. In this study, a series of experimental tests was conducted to elucidate the coupled effects of inherent and induced anisotropy on reliquefaction resistance of Toyoura sand, which have not been studied before. Accordingly, loose and dense Toyoura sands were prepared with two different methods: dry deposition and moist tamping. The specimens were sheared cyclically using a hollow cylinder torsional shear apparatus under various cyclic stress ratios up to different residual shear strains (γres) and reconsolidated at different states. The experimental results were assessed from various perspectives, including stress–strain relationships, failure mechanisms, liquefaction/reliquefaction resistance, excess pore water pressure (EPWP) generation and compressibility in conjunction with micromechanical interpretations. It was shown that fabric evolution affects the reliquefaction characteristics of Toyoura sand substantially. Interestingly, a unique correlation exists between EPWP and shear strain accumulation for all tests. An energy-based model was developed to uniquely correlate the dissipated energy with the cyclic resistance based only on residual shear strains; this model shows great promise to develop a unified, energy-based criterion for quantifying the liquefaction/reliquefaction resistance of soils with different fabrics. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Modelling unsaturated silty tailings and the conditions required for static liquefaction.
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Wang, Yanzhi, Vo, Thanh, and Russell, Adrian R.
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PORE water pressure , *TAILINGS dams , *WATER table , *PORE water , *STORAGE facilities - Abstract
The potential for static liquefaction of tailings is a major focus in the design and operation of tailings storage facilities. This research models the behaviour of unsaturated tailings, with a variety of degrees of saturation, addressing the propensity for static liquefaction during monotonic loading. Unsaturated triaxial tests, including constant suction conditions and constant water–air mass conditions, were performed. A bounding surface plasticity model was used to simulate the results. The constant mass condition is relevant to undrained closed-system loading, which may prevail during fast deformation after the tailings becomes unstable, when the air and water in the pore space remain locked inside the tailings. Boyle's law and hydraulic hysteresis were accounted for to model the changes of pore air and water pressures, and suction, with the change in tailings volume. Good agreement was achieved between test results and model simulations. Additional simulations to mimic rising water tables under constant total stress states in the field, situations that may trigger instabilities, are also shown. Results are added to charts which relate peak and post-liquefaction strengths, as well as collapse lines, to measures of initial state, for unsaturated conditions, which may be of use in practice. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Analytical Solutions for Composite Foundations Reinforced by Partially Penetrated Stone Columns and Vertical Drains.
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Li, Chuanxun and Lu, Xiangzong
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STONE columns , *VERTICAL drains , *PORE water pressure , *SOIL consolidation , *FINITE element method - Abstract
ABSTRACT When stone columns or vertical drains are applied to improve soils, it is common to face situations where the soft soil layer is too thick to be penetrated completely. Although consolidation theories for soils with partially penetrated vertical drains or stone columns are comprehensive, consolidation theories for impenetrable composite foundations containing both two types of drainage bodies have been few reported in the existing literature. Equations governing the consolidation of the reinforced zone and unreinforced zone are established, respectively. Analytical solutions for consolidation of such composite foundations are obtained under permeable top with impermeable bottom (PTIB) and permeable top with permeable bottom (PTPB), respectively. The correctness of proposed solutions is verified by comparing them with existing solutions and finite element analyses. Then, extensive calculations are performed to analyze the consolidation behaviors at different penetration rates, including the total average consolidation degree defined by strain or stress and the distribution of the average excess pore water pressure (EPWP) along the depth. The results show that the total average consolidation rate increases as the penetration rate increases; for some composite foundations with a low penetration rate, the consolidation of the unreinforced zone cannot be ignored. Finally, according to the geological parameters provided by an actual project, the obtained solution is used to calculate the settlement, and the results obtained by the proposed solution are in reasonable agreement with the measured data. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Seasonal slow slip in landslides as a window into the frictional rheology of creeping shear zones.
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Finnegan, Noah J. and Saffer, Demian M.
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LANDSLIDE prediction , *PORE water pressure , *CREEP (Materials) , *SHEAR zones , *RHEOLOGY , *LANDSLIDES - Abstract
Whether Earth materials exhibit frictional creep or catastrophic failure is a crucial but unresolved problem in predicting landslide and earthquake hazards. Here, we show that field-scale observations of sliding velocity and pore water pressure at two creeping landslides are explained by velocity-strengthening friction, in close agreement with laboratory measurements on similar materials. This suggests that the rate-strengthening friction commonly measured in clay-rich materials may govern episodic slow slip in landslides, in addition to tectonic faults. Further, our results show more generally that transient slow slip can arise in velocity-strengthening materials from modulation of effective normal stress through pore pressure fluctuations. This challenges the idea that episodic slow slip requires a narrow range of transitional frictional properties near the stability threshold, or pore pressure feedbacks operating on initially unstable frictional slip. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Failure mechanism of loess landslide induced by water stagnation on the combined surface.
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Hou, Dayong, Zeng, Farong, Deng, Junfeng, Wei, Huan, and Xu, Rui
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LANDSLIDES ,PORE water pressure ,SHEAR testing of soils ,MARKOV chain Monte Carlo ,SHEAR strength of soils ,LANDSLIDE hazard analysis - Abstract
In order to reveal the destructive mechanism of loess landslide induced by stagnant water on the combined surface, and to clarify the influence of the main control factors, this paper takes a typical loess landslide in northern Shaanxi as the research object, analyzes the structure of the rock and soil body, and the excavation and filling construction through the geohazard survey, and analyzes the process of traction sliding caused by the stagnant water on the combined surface at the different stages of the project by combining with the calculation of the stability of the slope body. Further the article analyses the process of traction sliding caused by water on the combined area due to construction by means of a discrete element model, and delves into the mechanism of strength reduction of saturated loess. The results show that: 1) the combined surface stagnant water type loess landslide has the characteristics of sudden sliding and rapid evolution, which is highly hazardous and difficult to prevent and control; 2) the slope destabilization is controlled by the engineering geological conditions, and the slope excavation changes the original mechanical equilibrium conditions of the slope, which provides the dynamic conditions for the traction sliding of the slope; 3) the change of the hydrogeological environment results in the obstruction of the natural drainage channel, which leads to the formation of continuous sliding surface due to stagnant water on the combined surface, and the formation of a continuous sliding surface due to stagnant water on the combined surface. Surface stagnant water to form a continuous slippery surface, inducing the overall destabilization of the slope damage; 4) loess strength index with the increase of saturation and the exponential function form of reduction, and when the saturation degree reaches more than 80%, the strength index of the soil body to reach the basic stability. The article expanding the ideas of landslide control and analysis, and the research results will provide a theoretical basis for the design of junction landslide management in the loess areas of northern Shaanxi. [ABSTRACT FROM AUTHOR]
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- 2024
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11. A two‐stage combined filtration‐consolidation model for slurry ground treated by vacuum preloading.
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Ye, Xiaoqian, Shi, Li, and Cai, Yuanqiang
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PORE water pressure , *WATER reuse , *VERTICAL drains , *SOIL formation , *RECLAMATION of land - Abstract
The vacuum preloading technique is extensively employed for ground improvement, particularly for slurry ground characterized by high‐water content and low strength. Such ground frequently exhibits a delay in pore water pressure dissipation when treated with prefabricated vertical drains. To clarify the drainage and consolidation behaviour of high‐water content slurry ground under vacuum preloading, this study proposed a two‐stage combined model that integrates both filtration and consolidation processes. Initially, an axisymmetric filtration model was used to describe the formation of the soil column through the radial migration and compaction of the particles. The end‐of‐filtration radial distributions of void ratio, permeability coefficient, and effective pressure served as initial conditions for the consolidation stage analysis. This stage was depicted using a large strain consolidation model based on the free strain condition. The results showed the necessity of incorporating the filtration stage to capture the overall drainage mechanism and characteristics of slurry ground with vacuum preloading treatment. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Analysis of the Influence of Boundary Permeability Characteristics Under Fluid–Solid Coupling on Surface Subsidence in Deep Near‐Horizontal Coal Seam Mining.
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Sun, Jie, Hao, Zhe, Liu, Le, Zhu, Yanfei, Shen, Cheng, and Zhao, Zhipeng
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MINE subsidences , *PORE water pressure , *COAL mining , *GROUNDWATER , *LAND subsidence , *LONGWALL mining - Abstract
The fluid–solid coupling effect is an important factor which cannot be ignored to study the surface subsidence of deep coal seam mining in the area with abundant underground water. To study the influence of boundary permeability characteristics on surface subsidence in deep near‐horizontal coal seam mining under the effect of fluid–solid coupling, the pore water pressure field, vertical stress field, surface subsidence, and vertical displacement of a rock seam during deep mining under different permeability boundary conditions were analyzed based on fluid–solid coupling theory, taking the 3−1501 working face of Erdos Hongqinghe coal mine as an example. The results revealed that the permeability characteristics of different hydraulic boundaries affected the pore water pressure, vertical stress in the rock layer, and surface subsidence during deep mining. Moreover, the trends of pore water pressure, vertical stress, and surface subsidence of a fixed‐head permeability boundary were largely the same as those under impermeable boundary conditions, but the calculated results of the fixed‐head permeability boundary were lower than those for the impermeable boundary at the same depth. The maximum surface subsidence for the fixed‐head permeable boundary condition and the impermeable boundary condition was 879 and 925 mm, respectively, which were 239 and 285 mm higher than those obtained when the fluid–solid coupling effect was neglected (an increase of 37.3% and 44.5%, respectively). The field monitoring trend for the subsidence basin aligns closely with the subsidence basin trend under the influence of fluid–solid coupling. Considering the constant head permeable boundary conditions in the context of fluid–solid coupling yields accurate surface subsidence results. The results have provided a theoretical basis for the analysis and prediction of coal mining surface subsidence considering the fluid–solid coupling effect. [ABSTRACT FROM AUTHOR]
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- 2024
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13. The influence of rainfall patterns on factor of safety for clayey soil slopes.
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Mohammad, Ashrafullah Shafi, Satyanaga, Alfrendo, Abilev, Zheniskan, Bello, Nura, Nadezhda, Kozyukova, Zhai, Qian, Sung-Woo Moon, Jong Kim, and Rui Chen
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PORE water pressure ,SLOPE stability ,SLOPES (Soil mechanics) ,RAINFALL ,WATER table ,SOIL mechanics ,LANDSLIDES - Abstract
The persistent trend of rising temperatures and shifting weather patterns caused by climate change has prompted significant concern around the world. This research aims to evaluate the instability of slopes in Almaty, Kazakhstan, under various rainfall patterns, groundwater tables, and slope geometries by incorporating the principles of unsaturated soil mechanics. However, there have been a limited number of studies incorporating the principle of unsaturated soil mechanics with constant rainfall patterns in Central Asia, particularly in Kazakhstan, on the impact of rainfall-causing landslides. Hence, in this research, GeoStudio software (SEEP/W and SLOPE/W) was used to simulate the factor of safety (FoS) and pore water pressure for the investigated slopes under different rainfall patterns. Results from Hyprop and statistical method show that the saturated volumetric water content is 0.502, whereas the residual one is 0.147 and for the permeability function the conductivity coefficient started to sharply decrease at the suction value of 2 kPa when the air-entry value was 24 kPa. Findings from numerical analysis show the change in FoS for the slope of 10mheight and 27-degree slope angle was 6%, 7%, 7%, and 8% for cyclic, delayed, advanced, and normal distributions, respectively. For the slope with 20 m height and the same 27-degree angle, the change in FoS was 8%, 10%, 8%, and 11% for the cyclic, delayed, advanced, and normal distributions, respectively. These same patterns were shown in slopes with 35-degree and 45-degree angles, having the same 10 m and 20 m heights. Comparatively, this shows that slopes under cyclic rainfall patterns (240mmof rain within 12 days) are less prone to failure compared to slopes under continuous, delayed, or regularly distributed rainfall patterns. Moreover, an increase in slope height and angle also affect the FoS negatively. It should be noted that the results obtained are only applicable to clayey-loam soil. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Analysis and monitoring of the behavior of a rock fill dam ten years after construction: a case study of the Iran-Madani Dam.
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Farajniya, Rasoul, Poursorkhabi, Ramin Vafaei, Zarean, Ahmad, and Dabiri, Rouzbeh
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EARTH dams ,PORE water pressure ,DAM safety ,NUMERICAL analysis ,BEHAVIORAL assessment ,DAM design & construction - Abstract
In this study we compared dam monitoring results with those of numerical analysis to propose a plan for the first reservoir impounding of the Iran-Madani Rock fill dam, ten years after the completion of its construction. The stability of the dam body has been assessed using numerical analysis and data obtained from sensors installed in the dam. The correctness and accuracy of the geotechnical parameters of the dam body materials were confirmed by comparing the results of numerical analysis and monitoring through back analysis. The linear correlation coefficients between the experimental data and the numerical results for settlement, pore water pressure, and total stress are 84%, 67%, and 99%, respectively. In addition, the agreement between the design assumptions with both the numerical analysis results and instrumentation data was examined. The arching ratio values obtained from instrumentation and numerical analysis in the core of the dam are 0.47 and 0.35, respectively, indicating the safety of the dam. Finally, a numerical sensitivity analysis was conducted to present a special impounding program for the dam, with a focus on controlling simultaneous changes in pore water pressure and effective stress in the clay core, ten years after the completion of the dam body construction. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Exploring the integration of InSAR data into climate‐driven creep models to assess slow‐moving landslide dynamics.
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Marte, Roman, Keuschnig, Markus, Neureiter, Patrik, Ramoser, Hannes, and Valentin, Gerald
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PORE water pressure , *RAINFALL frequencies , *SYNTHETIC aperture radar , *PRECIPITATION (Chemistry) , *RAINFALL , *LANDSLIDES - Abstract
The deformation behavior of slow‐moving large landslides is often governed by rainfall characteristics. Based on observational data such as precipitation, deformation measurement, and pore water pressure measurements in the slip zone, in many cases a strong correlation between strong rainfall events, a time‐delayed increase of pore water pressures in the slip zone, and, simultaneously to this, an increase of the deformation rate of the landslide can be found. Based on such detailed data, calculation models, which couples the relation between rainfall characteristics and the development of pore water pressures in the slip zone on one hand and the deformation behavior of the slope on the other, can be developed and be used for a better understanding and a prediction of deformation behavior of such slow‐moving landslides. Climate change issues will lead to a change in rainfall frequency and magnitude and annual temperature distribution characteristics in several regions worldwide, which will also lead to changes in the deformation behavior of such large landslides. In this contribution, satellite‐based interferometric synthetic aperture radar (InSAR) data are discussed to be used as source for deformation measurements as bases for prediction models describing the rainfall‐triggered deformation behavior of slow‐moving landslides. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Face stability assessment of a longitudinally inclined tunnel considering pore water pressure.
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Chen, Guang‐Hui, Zou, Jin‐Feng, Guo, Yuan‐Cheng, Tan, Zi‐An, and Dan, Shu
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PORE water pressure , *WATER tunnels , *EVIDENCE gaps , *WATER table , *TUNNELS - Abstract
The face stability analysis of a longitudinally inclined shield tunnel using an analytical approach in water‐rich areas is still a research gap. To solve this face stability problem, a numerical simulation based on the FLAC3D is first conducted to calculate the seepage field behind the inclined tunnel face. An improved rotational failure mechanism is developed to make it possible to investigate the face stability of inclined tunnels using analytical approaches. In the framework of the kinematic approach of limit analysis, the limit support pressures and corresponding failure surfaces of the inclined tunnel face are determined to analyze the face stability issue. The interpolation tool (griddata) in MATLAB is adopted to involve the obtained numerical values of pore water pressures into the analysis of the stability issue. The analytical solutions obtained from the proposed method are validated by comparisons with existing results from published literatures and numerical results. For a quick estimation of the inclined tunnel face stability in water‐rich areas, a series of design charts are then presented for various soil strength parameters, water tables, and inclined angles. Finally, an application of the proposed method to a practical tunneling case is provided, which further illustrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
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- 2024
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17. Interfacial flow contact resistance effect for thermal consolidation of layered viscoelastic saturated soils with semi‐permeable boundaries.
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Xie, Jiahao, Wen, Minjie, Ding, Pan, Tu, Yuan, Wu, Dazhi, Liu, Kaifu, Tang, Kejie, and Chen, Menghuan
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WATERLOGGING (Soils) , *PORE water pressure , *LAMINAR flow , *SETTLEMENT of structures , *EXPERIMENTAL literature - Abstract
Laminar flow phenomena may occur when pore water flows at low velocities across the interfaces between soils of different properties, thus causing flow contact resistance. To explore the impacts of interfacial flow contact resistance and rheological characteristics on the thermal consolidation process of layered viscoelastic saturated soil foundation featuring semi‐permeable boundaries. This paper established a new thermal consolidation model by introducing a fractional order derivative model, Hagen–Poiseuille law and time‐dependent loadings. The semi‐analytical solutions for the proposed thermal consolidation model are derived through the Laplace transform and its inverse transform. The reliability and correctness of the solutions are verified with the experimental data in literatures. The influence of constitutive parameters, flow contact resistance model parameters on thermal consolidation process and the interfacial flow contact resistance on foundation settlement, is further explored. The results indicate that the impact of the constitutive parameters and permeability coefficient on the thermal consolidation of viscoelastic saturated soil is related to the flow contact resistance. The enhanced flow contact resistance effect leads to a significant increase in pore water pressure and displacement during the consolidation process. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
- View/download PDF
18. Machine learning prediction model for clay electrical conductivity and its application in electroosmosis consolidation.
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Zhang, Xunli, Zheng, Lingwei, Zheng, Xudong, Wang, Hengyu, Ge, Shangqi, and Xie, Xinyu
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ELECTRIC conductivity of soils , *MACHINE learning , *LEAST squares , *ELECTRIC conductivity , *PORE water pressure - Abstract
The electrical conductivity of soil is closely associated with various physical properties of the soil, and accurately establishing the interrelationship between them has long been a critical challenge limiting its widespread application. Traditional approaches in geotechnical engineering have relied on specific conduction mechanisms and simplifying assumptions to construct theoretical models for electrical conductivity. This paper adopts a different approach by using machine learning methods to predict the electrical conductivity of clay materials. A reliable dataset was generated using the quartet structure generation set to create random clay microstructures and calculate their electrical conductivity. Based on this dataset, machine learning methods such as least squares support vector machine and backpropagation neural networks outperform theoretical models in terms of prediction accuracy and resistance to interference, with a coefficient of determination (R2) exceeding 0.995 when unaffected by disturbances. The computation of Shapley values for input features aids in explicating the machine learning model. The results reveal that saturation is a key feature in predicting electrical conductivity, while porosity and constrained diameter are relatively less important. Finally, an already trained model is applied to the one-dimensional electroosmosis-surcharge preloading consolidation theory. The results of the calculations demonstrate that neglecting changes in soil electrical conductivity during electroosmosis can lead to an overestimation of the absolute values of anode excess pore water pressure and soil settlement. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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19. Undrained cyclic responses of biocemented calcareous silty sand.
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Xiao, Yang, Hu, Jian, Shi, Jinquan, Zhang, Lei, and Liu, Hanlong
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PORE water pressure , *MICROSCOPY , *CALCIUM carbonate , *MARINE engineering , *SAND - Abstract
Microbially induced calcium carbonate precipitation (MICP) technology is an emerging and environmentally sustainable method for improving the strength and stiffness of soil. Specifically, this innovative approach has gained favor in marine engineering due to the advantaged compatibility between precipitated calcium carbonate induced by MICP and coral sand. Sand containing fines is susceptible to liquefy. Whereas, the impact of fines contents on cyclic behavior of MICP-treated calcareous sand remains uncertain. Consequently, this technical note aims to investigate the liquefaction behavior of biocemented calcareous silty sand by conducting undrained cyclic triaxial shear tests and microscopic analysis. The results revealed the patterns of the excess pore water pressure curves and cyclic deformation characteristics as the fines contents increased. The liquefaction resistance of biocemented sand initially decreases with the addition of fines but subsequently exhibits an increasing trend. Microscopic analysis showed that at the cementation level with the cementation solution concentration of 1 mol/L, the calcium carbonate crystals are mainly attached to the surface of sand grains and this pattern does not directly affect the force chain. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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20. Field tests on behavior of the surrounding soil during helical piles installation in silty clay.
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Kong, Gangqiang, Hu, Shuaijun, Zhou, Yang, Yu, Jianghua, and Zou, Benwei
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PORE water pressure , *EARTH pressure , *SOILS , *CLAY - Abstract
Helical piles can be classified as partial displacement piles in terms of moderate advancement rate. However, its installation effect on surrounding soil is unclear. This study presented four field tests on the installation of helical piles with various dimensions in silty clay. The radial earth pressure and excess pore water pressure were measured during the installation processes. The installation effect of helical pile embedded in silty clay was comprehensively discussed and evaluated from multiple dimensions of time and space, based on the cavity expansion method (CEM) and Randolph and Wroth's elastic–plastic method verified by field data. The research reveals that as the length of the helical pile increases by 1.0 time, the maximum variations in radial earth pressure and pore water pressure by a remarkable 25.0 times and 7.8 times, respectively. Additionally, when the shaft diameter of the helical pile expands by 20%, the maximum alterations in radial earth pressure and pore water pressure swell by approximately 18.6 and 5.7%, respectively. Comparing the radial earth pressure at various embedment depths at the same penetration stage, it is found that the radial earth pressure induced by helices is slightly greater than that induced by pile shaft. The estimated radial earth pressure and pore water pressure agree with the measured maximum data, and the pore water pressure generated by the installation of helical pile completely dissipates after 10–12 days of installation in this work. [ABSTRACT FROM AUTHOR]
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- 2024
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21. Study on Pore Water Pressure Model of EICP-Solidified Sand under Cyclic Loading.
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Li, Gang, Li, Yu, Hua, Xueqing, Liu, Jia, Yang, Shasha, and Zhang, Yao
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CYCLIC loads , *FREQUENCIES of oscillating systems , *POLLUTION , *CALCIUM carbonate , *ENVIRONMENTAL protection , *PORE water pressure - Abstract
Under traffic load, earthquake load, and wave load, saturated sand foundation is prone to liquefaction, and foundation reinforcement is the key measure to improve its stability and liquefaction resistance. Traditional foundation treatment methods have many problems, such as high cost, long construction period, and environmental pollution. As a new solidification method, enzyme-induced calcium carbonate precipitation (EICP) technology has the advantages of economy, environmental protection, and durability. Through a triaxial consolidated undrained shear test under cyclic loading, the impacts of confining pressure (σ3), cementation number (Pc), cyclic stress ratio (CSR), initial dry density (ρd), and vibration frequency (f) on the development law of pore water pressure of EICP-solidified sand are analyzed and then a pore water pressure model suitable for EICP-solidified sand is established. The result shows that as σ3 and CSR increase, the rise rate of pore water pressure of solidified sand gradually accelerates, and with a lower vibration number required for liquefaction, the anti-liquefaction ability of solidified sand gradually weakens. However, as Pc, ρd, and f rise, the increase rate of pore water pressure of solidified sand gradually lowers, the vibration number required for liquefaction increases correspondingly, and its liquefaction resistance gradually increases. The test results are highly consistent with the predictive results, which show that the three-parameter unified pore water pressure model is suitable for describing the development law of A-type and B-type pore water pressure of EICP-solidified sand at the same time. The study results provide essential reference value and scientific significance in guidance for preventing sand foundations from liquefying. [ABSTRACT FROM AUTHOR]
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- 2024
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22. Evaluation of the effects of EPS composite soil replacement on the dynamic performance of caisson structure using shaking table tests.
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Gao, Hongmei, Ji, Zhanpeng, Zhang, Xinlei, Zhang, Shushan, Wang, Zhihua, and Shen, Guangming
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SHAKING table tests , *PORE water pressure , *SOIL liquefaction , *EARTH pressure , *LATERAL loads - Abstract
The seismic performance of a caisson structure under two types of models with a saturated sandy foundation (CSS) and an expanded polystyrene (EPS) composite soil foundation (CES) are studied using shaking table tests. The macro phenomena of the two different foundation models are described and analyzed. The effects of the replacement of EPS composite soil on seismic-induced liquefaction of backfill and the dynamic performance of a caisson structure are evaluated in detail. The results show that the excess pore water pressure generation in the CES is significantly slower than that in the CSS during the shaking. The dynamic earth pressure acting on the caisson has a triangular shape. The response of horizontal acceleration, displacement, settlement, and rotation angle of the caisson in the CES is smaller than that in the CSS, which means the caisson in the CES has a better seismic performance. Furthermore, the out-of-phase phenomenon between dynamic earth thrust and inertial force in the CES is more obvious than that in the CSS, which is beneficial to reduce the lateral force and improve the stability of the caisson structure. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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23. Investigating the Creep Damage and Permeability Evolution Mechanism of Phyllite Considering Non-Darcy's Flow.
- Author
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Li, Tianbin, Peng, Feng, Chen, Chao, Ma, Chunchi, Li, Yonglin, Wang, Yixiang, and Li, Yushu
- Subjects
- *
ROCK creep , *PORE water pressure , *HYDRAULIC couplings , *ACOUSTIC emission , *OSMOTIC pressure , *SEEPAGE - Abstract
This study investigates the intricate interplay of hydraulic coupling, creep damage, and permeability evolution mechanisms in phyllite, focusing on their relevance to tunnel engineering design and long-term stability in soft rock formations. To achieve this, conventional triaxial tests were conducted on saturated phyllite specimens under creep-seepage acoustic emission conditions. The results were systematically analyzed to unveil the inherent characteristics of creep deformation, seepage rate evolution, and damage progression in phyllite when subjected to stress–seepage coupling. Furthermore, a permeability model for representative volume element (RVE) was developed based on meso-mechanics principles, considering the distinctive attributes of low-permeability non-Darcy's flow in rock. Consequently, a novel relationship between effective damage and permeability was established. We determined that seepage pressure induces three key effects on the creep damage mechanism of phyllite samples: (1) It adds to the existing stress through the superposition of osmotic pressure and axial load, (2) it induces tensile expansion stress because of pore water pressure, and (3) it softens the fracture surfaces to some extent. More importantly, this study validates the relationship between effective damage and permeability through the fitting of creep and damage parameters, which were obtained from the test results, and it reveals a square relationship between subsequent damage and permeability under stress conditions. The findings of this study provide a robust theoretical foundation for comprehending the evolution of damage and permeability characteristics during the creep process of rock under seepage conditions. We obtained essential insights and quantitative analyses for comprehending the damage mechanisms in rock creep under hydraulic coupling, which has significant implications for tunnel engineering and long-term rock stability assessments in soft rock environments. Highlights: Model developed for RVE element based on meso-mechanics to consider low-permeability non-Darcy seepage in rock. Relationships between effective damage and permeability analyzed. Creep damage mechanism of phyllite under stress–seepage coupling investigated. Evolution law of damage and permeability properties of phyllite under seepage condition clarified. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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24. Effects of Spatial Variation in Relative Density on Seismic Behavior of Saturated Sandy Ground.
- Author
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Sawatsubashi, Masahiro, Ishimaru, Makoto, Kobayashi, Takaaki, Hiraga, Kenji, and Nakamura, Hideki
- Subjects
- *
PORE water pressure , *STRAINS & stresses (Mechanics) , *SPECIFIC gravity , *RANDOM fields , *SPATIAL variation - Abstract
Proper consideration of variations in soil properties and their effects is necessary to enhance the seismic safety of structures. In this study, the effect of spatial variations in the cyclic resistance ratio on seismic ground behavior was investigated. Initially, dynamic centrifuge model tests were conducted on sandy ground featuring a 20% mixture of weak zones with low relative density and on homogeneous sandy ground with no mixture of weak zones. Subsequently, an effective stress analysis was performed by modeling the distribution of weak zones in the centrifuge model tests. Finally, after confirming the validity of the parameter settings, several analytical models with different weak-zone distributions were generated and numerically analyzed using random field theory. The results indicate that a local mixing of approximately 20% weak zones has only a limited effect on overall ground behavior. However, differences were observed in the rate of increase and dissipation of the excess pore water pressure ratio and in the residual horizontal displacement. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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25. Landslides triggered by the 2024 Noto Peninsula earthquake.
- Author
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Loi, Doan Huy, Jayakody, Sanchitha, Sassa, Kyoji, Konagai, Kazuo, Hirota, Kiyoharu, Ono, Atsutoshi, Takanaka, Takashi, Oki, Tomonori, and Minamitani, Taichi
- Subjects
- *
LANDSLIDE hazard analysis , *DISASTER resilience , *PORE water pressure , *LANDSLIDES , *EARTHQUAKES , *EARTH sciences - Abstract
The article discusses the landslides triggered by the 2024 Noto Peninsula earthquake in Ishikawa Prefecture, Japan. The earthquake, with a magnitude of 7.6, caused extensive damage and claimed 244 lives. Over 2300 landslides were triggered by the earthquake, including the Machinomachi and Ichinose landslides, which destroyed multiple houses. The article presents the results of field surveys, ring shear tests, and computer simulations to understand the mechanism of the landslides and validate the simulation results. The study highlights the importance of understanding long-runout landslides for future earthquake risk assessment. [Extracted from the article]
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- 2024
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26. Random analysis of deposit landslide deformation under uniformly increasing rainfall using machine learning.
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Kouame, Adangba Raphael and Wang, Huanling
- Subjects
- *
DISTRIBUTION (Probability theory) , *PORE water pressure , *SOIL density , *MAXIMUM likelihood statistics , *NATURAL disasters , *LANDSLIDES - Abstract
Landslides are one natural disaster in the mountains, causing damage to properties, destruction of infrastructure and loss of life. While landslide deformation and displacement are commonly observed through experimental investigation of the prototype models, this time-consuming approach might involve human errors and inaccurate constitutive models. This study aims to propose a numerical approach based on machine learning for substituting experimental investigation. In pursuit of this objective, the probability-weighted moments (PWMs) for generalised extreme value distribution (GEVD) were implemented to predict the deposit landslide deformation under uniformly increasing rainfall. The deposit landslide of the Dahua was selected as the case study. The accuracy and reliability of the proposed PWM are validated through the maximum likelihood method and the Jenkinson method. The PWM with GEVD is used to derive the progressive failure of the deposit landslide stability under the return period, the pore water pressure variation and the return period's effect. The results show that the proposed solution is suitable for predicting the responses of landslides. Moreover, the results demonstrate the importance of soil density; 30% of the deposited soil was moved when the soil density was 2 g/cm3 besides, and more than 90% were moved at the top of the slope for the soil density equal to 3 g/cm3. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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27. Experimental study on dewatering and reinforcement of dredged slurry treated by PHDs-PVDs under step vacuum preloading.
- Author
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Yang, Kang, Lu, Mengmeng, Sun, Jinxin, and Liu, Ganbin
- Subjects
- *
PORE water pressure , *VERTICAL drains , *SOIL moisture , *SOIL profiles , *SCANNING electron microscopy - Abstract
Nowadays, the utilization of prefabricated vertical drains (PVDs) or prefabricated horizontal drains (PHDs) in combination with vacuum preloading (VP) has emerged as a prevalent and effective strategy for treating dredged slurry. Nevertheless, both of these methods possess certain inherent limitations. In this study, three groups of parallel model experiments are conducted to compare the effectiveness of PVDs, PHDs and PHDs-PVDs under step VP in treating dredged slurry. Firstly, the water discharge, settlement and pore water pressure are monitored during the experiments. Then, the shear strength and water content of the soil at various locations after experiments are measured and the soil profiles at different cross sections are gauged. Additionally, soil excavation is conducted to evaluate the deformation characteristics of PHDs and PVDs. Finally, a scanning electron microscopy analysis is to assess the clogging of filter membranes. The results indicate that the proposed method can combine the advantages of both PHDs and PVDs, effectively enhancing the treatment effectiveness of the slurry. These findings elucidate the dewatering and reinforcement mechanism of PHDs-PVDs-VP and provide valuable insights for its practical engineering application. • A novel tridimensional crossed drainage system with PHDs-PVDs-VP is proposed. • Three groups of parallel model experiments are conducted to compare the effectiveness of PVDs, PHDs and PHDs-PVDs under step VP in treating dredged slurry. • The deformation and clogging of PVDs and PHDs are analyzed macroscopically and microscopically. • The dewatering and reinforcement mechanism of dredged slurry treated PHDs-PVDs-VP is revealed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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28. Field evaluation of moisture-suction regime and modulus of geosynthetic-reinforced soil wall with geo-composite side-drain.
- Author
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Chaiprakaikeow, Susit, Jotisankasa, Apiniti, Praphatsorn, Washirawat, Shrestha, Avishek, Cheento, Sawek, Pramusandi, Sony, Chaisri, Pragith, and Inazumi, Shinya
- Subjects
- *
PORE water pressure , *SOIL moisture , *MODULUS of rigidity , *WATERLOGGING (Soils) , *SOIL wetting - Abstract
Geosynthetic-reinforced soil (GRS) walls built on hillslopes are more increasingly incorporated with geo-composite side drain in order to prevent the side-seepage entering the fill. This study evaluates the long-term moisture, pore-water pressure, and shear modulus, of a 6.5 m-high geogrid-reinforced soil wall in western Thailand. Through extensive field monitoring and in-situ spectral analysis of surface wave (SASW) tests, conducted during the Years 2018–2019, as well as laboratory tests, several key findings emerge. Free-free resonant frequency (FFR) testing of non-reinforced samples reveals the role of soil wetting and drying history and hysteresis in the stiffness-moisture relationship. In-situ pore-water pressure was found to be highest below the road surface near the wall face, decreasing with depth due to underdrainage, with values ranging from −27 to 5 kPa. The intersection of the side drainage board with the underdrain bottom layer shows the highest water content. In-situ and laboratory-derived soil-water retention curve (SWRC) were found to differ at greater depths. In unsaturated conditions, the in-situ small strain modulus of GRS appeared insensitive to suction stress below 10 kPa but was slightly affected under positive pore-water pressure, with multiple linear regression modeling indicating a dependency of stiffness on depth and pore-water pressure. • Uncertainties persist regarding pore water pressure distribution in the fill when designing geosynthetic-reinforced soil walls. • This study evaluates the long-term moisture, pore-water pressure, and shear modulus, of a 6.5 m-high GRS wall with modular side drains. • Pore-water pressure was highest near the wall face just below the pavement, and diminished with depth due to underdrainage. • In-situ G₀ of GRS wall was insensitive to suction stress in unsaturated conditions but slightly affected once the soil became saturated. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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29. Mechanical Behavior of Natural Granite Residual Soil in Simple Shear.
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Liu, Xinyu, Miao, Yu, Zhang, Xianwei, and Yin, Song
- Subjects
- *
PORE water pressure , *SHEAR strength of soils , *CYCLIC loads , *SOIL weathering , *SOIL structure - Abstract
The geotechnical behavior of residual soil differs essentially from that of sedimentary soil because of the weathering pedogenesis of the former, thereby posing significant difficulties in predicting soil response. In this study, the shear strength and stiffness of natural granite residual soil are evaluated through systematic monotonic and cyclic simple shear tests performed using a hollow-cylinder apparatus. Simple shear testing provides critical information about soil behavior under plane-strain conditions and involves principal stress rotation, which is beyond the scope of triaxial shear tests. The mechanical properties of granite residual soil measured in monotonic simple shear are found to be different from those obtained through other routine laboratory tests such as triaxial shear and resonant column tests. Whereas the conventional triaxial compression test gives unconservatively high soil strength parameters, those from simple shear testing appear more reasonable than the triaxial results. The cyclic behavior of residual soil in simple shear is dominated by the cyclic stress ratio, a higher value of which results in more significant deformation and pore water pressure build-up as well as more rapid stiffness degradation. This is particularly the case when the cyclic stress ratio exceeds a critical value in the range of 0.125–0.1875. No consistent pattern can be established for how the loading frequency influences soil responses within the range of 0.01–1.0 Hz. This study enriches the techniques for characterizing residual soil and provides new data sets about its mechanical behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Greenfield Response to EPBM Tunneling in Paris and Relations with TBM Operation Variables.
- Author
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Michalski, Agathe, Branque, Denis, Berthoz, Nicolas, Rallu, Antoine, Mohamad, Wassim, Szymkiewicz, Fabien, Le Kouby, Alain, and Bourgeois, Emmanuel
- Subjects
- *
PORE water pressure , *WATER tunnels , *EARTH pressure , *TUNNEL design & construction , *OPEN-ended questions - Abstract
A major full-scale experiment called the Tunnelling and Limitation of Impacts on Piles (TULIP) project was conducted in 2020 on Line 16 of the Grand Paris Express project to analyze the tunnel boring machine–soil–pile interactions during tunnel excavation near deep structures. This paper presents the greenfield ground response observed when the tunnel boring machine (TBM) crossed the TULIP site: surface displacements, subsurface displacements, and pore water pressures are presented. The originality of the paper lies in the fact that details are provided not only on the site geological and geotechnical characteristics, but also on the TBM operation: a detailed analysis of the variations in pressure inside the cutting chamber of the earth-pressure balanced machine (EPBM) is proposed. This paper reports factual data without bias induced by a preconceived numerical model, but highlights open questions that challenge the advanced numerical models, that will be required to analyze completely the tunnel–soil–pile interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Energy-Based Liquefaction Evaluation: The Port of Kushiro in Hokkaido, Japan, 2003 Tokachi-Oki Earthquake.
- Author
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Ko, Kil-Wan, Kayen, Robert E., Kokusho, Takaji, Ilgac, Makbule, Nozu, Atsushi, and Nweke, Chukwuebuka C.
- Subjects
- *
PORE water pressure , *SOIL liquefaction , *PRESSURE transducers , *EARTHQUAKES , *STRAIN energy - Abstract
The magnitude (Mw) 8.3 Tokachi-oki earthquake occurred in September 2003, causing extensive damage in Hokkaido, Japan, and triggering extensive soil liquefaction in the region. The Port of Kushiro was one of the locations where surficial evidence of liquefaction was observed but was also a well-instrumented location with four pore-water pressure transducers installed in the backfill of the quay wall. However, all of the sensors malfunctioned during the earthquake. As a result, the pore-water pressure response recorded by those sensors were inaccurate and unusable with regard to evaluating liquefaction triggering and extent. This study introduced the energy-based soil liquefaction evaluation to estimate the excess pore water pressure responses at the Port of Kushiro based on the cumulative strain energy of the soil during the 2003 Tokachi-oki earthquake. In order to apply the energy-based method to this case history, this study explored the empirical equation describing a relationship between normalized cumulative energy and excess pore water pressure ratio while incorporating the bidirectional shaking effect on strain energy development. Although the energy-based method allowed for the estimation of the time needed to trigger liquefaction at a target site, it was derived using the empirical coefficients that were developed for a different soil from those at the site of interest. This indicated that an adjustment to the estimated timing of liquefaction was needed, which was accomplished by additional evaluation through a Stockwell transform and Arias intensity-based liquefaction assessment. Both procedures indicated a similar timing of liquefaction at the site. Based on the updated time of liquefaction triggering, the empirical coefficient was recalibrated to estimate the excess pore water pressure ratio, and the result provided reasonable excess pore water pressure responses at the backfill of the Port of Kushiro during the 2003 Tokachi-oki earthquake. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Energy-Based and Strain-Based Methods for Estimation of Pore Water Pressure within Liquefied Soil Layers.
- Author
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Ko, Kil-Wan and Kayen, Robert E.
- Subjects
- *
PORE water pressure , *SOIL liquefaction , *SHEAR strain , *SHEARING force , *MODULUS of rigidity - Abstract
The evaluation of the excess pore water pressure ratio (ru), the ratio of the excess pore water pressure of the soil, is a defining approach to assessing liquefaction occurrence. Rarely is ru measured, so surficial observations of sand boils, fissures, and soil settlements have provided indirect evidence of liquefaction occurrence in case histories. Acceleration responses during undrained cyclic loadings incorporate shear strain and stress responses of the liquefied soil. Therefore, the use of acceleration responses can provide another indirect indication of liquefaction as the sudden drop in the frequency in the time–frequency domain in acceleration records. This study aimed to develop strain-based and energy-based methods for estimating the pore water pressure buildup based on the acceleration responses of liquefiable sand layers. The strain-based method linked the liquefaction-induced shear strain of the soil with ru through the shear modulus that is a function of the effective stress. An alternative approach used an energy-based method that linked pore-pressure generation with the energy dissipated in the soil. Centrifuge model tests for the liquefaction of soil were used to develop and validate the two methods, and these were applied to a case history, the 1987 Superstition Hill earthquake at the Wildlife site, for validation. To capture the variation of ru from its contractive to dilative responses, the amount of ru drop was estimated based on the peak shear stress when dilation spikes occurred. For the energy-based method, the centrifuge test results were used to derive empirical relations between ru and cumulative dissipated energy done by liquefiable soil. The estimated ru time-histories from the established methods were consistent with the measured responses in the centrifuge tests and the case history. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. A Comparative Study for Evaluating the Groundwater Inflow and Drainage Effect of Jinzhai Pumped Storage Power Station, China.
- Author
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Wu, Jian, Zhou, Zhifang, Wang, Hao, Chen, Bo, and Wang, Jinguo
- Subjects
PORE water pressure ,WATER pressure ,GROUNDWATER flow ,CAVES ,CONSTRUCTION projects - Abstract
Various hydrogeological problems like groundwater inflow, water table drawdown, and water pressure redistribution may be encountered in the construction of hydraulic projects. How to accurately predict the occurrence of groundwater inflow and assess the drainage effect during construction are still challenging problems for engineering designers. Taking the Jinzhai pumped storage power station (JPSPS) of China as an example, this paper aims to use different methods to calculate the water inflow rates of an underground powerhouse and evaluate the drainage effect caused by tunnel inflow during construction. The methods consist of the analytical formulas, the site groundwater rating (SGR) method, and the Signorini type variational inequality formulation. The results show that the analytical methods considering stable water table may overestimate the water inflow rates of caverns in drained conditions, whereas the SGR method with available hydro-geological parameters obtains a qualitative hazard assessment in the preliminary phase. The numerical solutions provide more precise and reliable values of groundwater inflow considering complex geological structures and seepage control measures. Moreover, the drainage effects, including a seepage-free surface, pore water pressure redistribution, and hydraulic gradient, have been accurately evaluated using various numerical synthetic cases. Specifically, the faults intersecting on underground caverns and drainage structures significantly change the groundwater flow regime around caverns. This comparative study can not only exactly identify the capabilities of the methods for cavern inflow in drained conditions, but also can comprehensively evaluate the drainage effect during cavern construction. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Exploring the Effects of Fissures on Hydraulic Parameters in Subsurface Flows from the Perspective of Energy Changes.
- Author
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Tao, Yu, Peng, Siwen, Chen, Jiazhou, Long, Shiping, and Liao, Bin
- Subjects
PORE water pressure ,SHEAR flow ,SOIL moisture ,WATER leakage ,FLOW velocity - Abstract
Reynolds number (Re), pore water pressure (P), and water flow shear force (τ) are primary indicators reflecting the characteristics of subsurface flow. Exploring the calculation of these parameters will facilitate the understanding of the hydrodynamic characteristics in different subsurface flows and quantify their differences. Hence, we conducted a study to monitor soil water content, matrix potential, and pore water pressure in two typical soil profiles (with and without fissures). The distribution of Re, P, and τ in both matrix flow (MF) and preferential flow (PF) were calculated with an improved calculation method, focusing on their energy changes. Results showed that these hydrologic parameters are quite different between MF and PF. Re values in MF remained below 0.1, indicating lower water flow velocities, while the Re values ranged from 0.8 to 2 in PF, indicating higher flow velocities. The P values in PF was tens to hundreds of times higher than that in MF, which is mainly due to the rapid accumulation and leakage of water within soil fissures. Additionally, the larger hydraulic radius and gradient in PF also resulted in higher τ values in PF (2~6 N m
−2 ) than in MF (0~1.5 N m−2 ). In PF, the pressure potential was the significant factor for τ, while τ in MF was dominated by the matrix potential and varies with the magnitude of the matrix potential gradient. This study suggests that Re, P, and τ could be considered as the major indexes to reflect dynamic characteristics of subsurface flow. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
35. Analytical Method of Spatiotemporal Evolution Characteristics of Unsteady Seepage Flow Pore Water Pressure in Front of Tunnel Face.
- Author
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Guo, Caixia, Wang, Zuozhen, Lin, Qingtao, Lu, Dechun, and Du, Xiuli
- Abstract
To evaluate the spatiotemporal evolution of pore water pressure in unsteady seepage flow ahead of a tunnel face, a partial differential equation for unsteady seepage is established. The ranges and boundary conditions of the unsteady seepage flow are specified, and the analytical solution of the unsteady seepage flow is obtained by the eigenfunction method. The obtained analytical solution additionally considers the time factor, which can be used to study the influence of seepage time on the seepage flow. And the pressure transmitting coefficient is introduced to analyze the influence of water and soil characteristics on the unsteady seepage. The analysis shows that the spatiotemporal evolution of the unsteady seepage flow pore water pressure ahead of a tunnel face is reflected in two aspects, the dissipation of the water pressure and the diffusion of the influence range of the unsteady seepage. The dissipation captures the gradual reduction of pore water pressure at a specific location as time progresses. Meanwhile, diffusion characterizes the alteration in the spatial distribution of water pressure. The pressure transmitting coefficient promotes the rate of unsteady seepage, while the height of water table has a greater influence on the magnitude of water pressure change in unsteady seepage flow. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Analytical Solution for 2D Electro‐Osmotic Consolidation of Unsaturated Soil With Non‐linear Voltage Distribution.
- Author
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Zhao, Xudong, Min, Jie, Ding, Shaolin, Liu, Yang, Liao, Jiaxin, and Zhang, Shuai
- Subjects
- *
PORE water pressure , *SOIL consolidation , *EIGENFUNCTION expansions , *AIR pressure , *ANALYTICAL solutions - Abstract
ABSTRACT Existing solutions for electro‐osmotic consolidation assume a linear voltage distribution, which is inconsistent with the experimental findings. The present study introduces a novel two‐dimensional electro‐osmotic consolidation model for unsaturated soils, which considers the influence of non‐linear voltage distribution. The closed‐form solution is derived by employing the eigenfunction expansion method and the Laplace transform technique. The accuracy of the analytical solutions is validated through the implementation of finite element simulations. The findings from the parametric studies indicate that the excess pore water pressure (EPWP) observed in electro‐osmotic consolidation is influenced by the distribution of voltage. The dissipation rate of EPWP is observed to be higher when subjected to non‐linear voltage conditions compared to linear voltage conditions. Moreover, the impact of non‐linear voltage distribution becomes more pronounced in unsaturated soil characterised by higher electro‐osmosis conductivity and a lower ratio of
kx/ky . In contrast, the excess pore air pressure (EPAP) remains unaffected by the voltage distribution. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
37. Comprehensive study on the stability and failure mechanism of landslides under rainfall and earthquake in northwest mountainous areas.
- Author
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Yang, Weixin, Zhang, Yonggang, Zhang, Lei, Bai, Gexue, Wan, Baofeng, An, Ning, Chaithong, Thapthai, Changho, Song, and Harith, Noor Sheena Herayani
- Subjects
LANDSLIDES ,ARTIFICIAL neural networks ,POISSON'S ratio ,LANDSLIDE hazard analysis ,SHAKING table tests ,PORE water pressure ,SEISMIC response ,SEISMIC waves - Abstract
This article presents a comprehensive study on the stability and failure mechanism of landslides in northwest mountainous areas under rainfall and earthquake conditions. The study focuses on the Lijie Beishan landslide as a typical case and combines on-site geological surveys with numerical simulations to evaluate its stability. The results show that the stability of the landslide decreases under static, rainfall, and earthquake conditions, with different failure modes observed. The study also compares different stability evaluation methods and provides valuable references for landslide stability evaluation in the region. The given text discusses the stability and failure process of a landslide using numerical simulation methods. The lower layer of the landslide is highly fragmented and prone to sliding due to its poor engineering properties. Human activities such as slope cutting and inappropriate land use contribute to the instability and sliding of the landslide. The text describes the principles and parameters used in the numerical simulation, including the use of finite element software and a viscoelastic constitutive model. The results of the simulation show the potential sliding surface and displacement of the landslide under different conditions. This document presents the results of a stability analysis of landslides in Lijie Beishan. The analysis was conducted under different conditions, including normal static, rainfall, and seismic conditions. The results indicate that the landslides have different failure modes and maximum deformations depending on the condition. The stability factor values were calculated to determine the stability state of the landslides, with values below 1 indicating instability. The analysis provides valuable information for understanding the [Extracted from the article]
- Published
- 2024
- Full Text
- View/download PDF
38. Prediction of Backward Erosion, Pipe Formation and Induced Failure Using a Multi‐Physics SPH Computational Framework.
- Author
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Ma, Guodong, Bui, Ha H., Lian, Yanjian, Nguyen, Tien V., and Nguyen, Giang D.
- Subjects
- *
PORE water pressure , *GEOTECHNICAL engineering , *EROSION , *FLUMES , *HYDRODYNAMICS , *LEVEES - Abstract
ABSTRACT Seepage‐induced backward erosion is a complex and significant issue in geotechnical engineering that threatens the stability of infrastructure. Numerical prediction of the full development of backward erosion, pipe formation and induced failure remains challenging. For the first time, this study addresses this issue by modifying a recently developed five‐phase smoothed particle hydrodynamics (SPH) erosion framework. Full development of backward erosion was subsequently analysed in a rigid flume test and a field‐scale backward erosion‐induced levee failure test. The seepage and erosion analysis provided results consistent with experimental data, including pore water pressure evolution, pipe length and water flux at the exit, demonstrating the good performance of the proposed numerical approach. Key factors influencing backward erosion, such as anisotropic flow and critical hydraulic gradient, are also investigated through a parametric study conducted with the rigid flume test. The results provide a better understanding of the mechanism of backward erosion, pipe formation and the induced post‐failure process. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Semi‐Analytical Solution for One‐Dimensional Nonlinear Consolidation of Multilayered Soil Considering Self‐Weight and Boundary Time Effect.
- Author
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Zong, Mengfan, Zhang, Jing, Wu, Wenbing, Yu, Ziye, Zhang, Yi, and Mei, Guoxiong
- Subjects
- *
PORE water pressure , *SOIL consolidation , *FINITE differences , *SOIL depth , *ANALYTICAL solutions - Abstract
ABSTRACT The self‐weight stress in multilayered soil varies with depth, and traditional consolidation research seldom takes into account the actual distribution of self‐weight stress, resulting in inaccurate calculations of soil consolidation and settlement. This paper presents a semi‐analytical solution for the one‐dimensional nonlinear consolidation of multilayered soil, considering self‐weight, time‐dependent loading, and boundary time effect. The validity of the proposed solution is confirmed through comparison with existing analytical solutions and finite difference solution. Based on the proposed semi‐analytical solution, this study investigates the influence of self‐weight, interface parameter, soil properties, and nonlinear parameters on the consolidation characteristics of multilayered soil. The results indicate that factoring in the true distribution of self‐weight leads to a faster dissipation rate of excess pore water pressure and larger settlement and settlement rate, compared to not considering self‐weight. Both boundary drainage performance and soil nonlinearity have an impact on consolidation. If the boundary drainage capacity is inadequate, the influence of soil nonlinearity on consolidation diminishes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. An Analytical Insight Into Stability Analysis of Unsaturated Multi‐Layered Slopes Subjected to Rainfall Infiltration.
- Author
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Yuan, Cheng, Qin, Changbing, Yang, Yueling, Sun, Zhibin, Li, Liang, Lei, Xiaoqin, and Chen Chian, Siau
- Subjects
- *
PORE water pressure , *SEPARATION of variables , *RAINFALL , *SLOPE stability , *SLOPES (Soil mechanics) - Abstract
ABSTRACT Slopes in nature usually present layered characteristics, and its stability is susceptible to rainfall events. Considering that current analytical solutions are only suited to simulate the rainfall infiltration of double‐layered infinite unsaturated slopes, an analytical procedure is hence proposed in this study to tackle the consideration of multiple layers. The variable separation method and transfer matrix method are combined to derive the analytical solution of pore water pressure (PWP) for simulating rainfall infiltration in layered infinite unsaturated slopes. After having validated the proposed model and analytical solutions by comparing with existing literature and numerical simulation, the closed‐form solution of PWP is incorporated into the limit equilibrium for assessing slope stability. A three‐layer slope is selected as an example for further discussion. PWP distribution and factor of safety are calculated, considering the effects of saturated hydraulic conductivity and thickness of the upper layer, intensity of antecedent and subsequent rainfall, and varied soil unit weight along the depth. The slope stability subjected to rainfall effects is consistent with the variation of PWP. The proposed analytical solutions provide a simple and practical avenue for computing PWP distribution and evaluating the stability of multi‐layered slopes under rainfall conditions, which can also serve as a benchmark for numerical solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Damage assessment of buildings due to land subsidence in Joshimath town of Northwestern Himalaya, India.
- Author
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Chourasia, Ajay, Dalbehera, Mickey Mecon, Kapoor, Ashish, Kulkarni, Kishor S., Gaurav, Govind, Singh, Satyavrat, and Kumar, R. Pradeep
- Subjects
PORE water pressure ,SOIL compaction ,LAND subsidence ,ARCHITECTURAL details ,CONSTRUCTION materials - Abstract
The process of land subsidence deals with the removal of excess pore water pressure and the compaction of soil mass under the effect of natural or human factors. The detrimental effects of land subsidence include changes in the morphology of the land surface and the formation of earth fissures, as well as structural and non-structural damage to surface and subsurface infrastructures. In Joshimath on 2nd January 2023, an incidence of ground subsidence occurred which damaged many buildings and infrastructures. This study addresses the exploratory work on rapid visual damage assessment of buildings based on method developed by National Disaster Management Authority (NDMA) and European Macroseismic Scale (EMS) − 98. The building vulnerability was assessed using building attributes like typology, number of storeys, area, construction materials, occupancy, configuration, construction practice etc. The damage attributes considered are based on siting issues, soil and foundation conditions, architectural features and elements, structural aspects and components, material & construction details, crack monitoring etc. In the critical buildings, cracks were monitored using crack meters. This study concludes out of total 2364 building surveyed, 37%, 42%, 20%, 1% buildings fall under "Usable", "Further Assessment", "Unusable", "to be demolished", grades respectively. [ABSTRACT FROM AUTHOR]
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- 2024
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42. Numerical Simulation of Water Migration during Soil Freezing and Its Resulting Characterization.
- Author
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Zhou, Bicheng, Brouchkov, Anatoly V., Eremina, Lidia I., Xu, Chunguang, and Hu, Jiabo
- Subjects
PORE water pressure ,PHASE transitions ,FROST heaving ,FROZEN ground ,SOIL freezing - Abstract
Water migration behavior is the main cause of engineering disasters in cold regions, making it essential to understand its mechanisms and the resulting mechanical characteristics for engineering protection. This study examined the water migration process during soil freezing through both experimental and numerical simulations, focusing on the key mechanical outcomes such as deformation and pore water pressure. Initially, a series of controlled unidirectional freezing experiments were performed on artificial kaolin soil under various freezing conditions to observe the water migration process. Subsequently, a numerical model of water migration was formulated by integrating the partial differential equations of heat and mass transfer. The model's boundary conditions and relevant parameters were derived from both the experimental processes and existing literature. The findings indicate that at lower clay water content, the experimental results align closely with those of the model. Conversely, at higher water content, the modeled results of frost heaving were less pronounced than the experimental outcomes, and the freezing front advanced more slowly. This discrepancy is attributed to the inability of unfrozen water to penetrate once ice lenses form, causing migrating water to accumulate and freeze at the warmest ice lens front. This results in a higher ice content in the freezing zone than predicted by the model, leading to more significant freezing expansion. Additionally, the experimental observations of pore water pressure under freeze–thaw conditions corresponded well with the trends and peaks projected by the simulation results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Cyclic liquefaction resistance of MICP- and EICP-treated sand in simple shear conditions: a benchmarking with the critical state of untreated sand.
- Author
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Ahenkorah, Isaac, Rahman, Md Mizanur, Karim, Md Rajibul, and Beecham, Simon
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PORE water pressure , *CYCLIC loads , *SOIL mechanics , *CALCIUM carbonate , *SAND - Abstract
In the present study, the undrained cyclic behaviour of biotreated sands using microbial and enzyme-induced carbonate precipitation was investigated for a wide range of initial void ratio after consolidation ( e 0 ), initial effective normal stress ( σ N 0 ′ ) and calcium carbonate content (CC) under direct simple shear (DSS) testing conditions. The critical state soil mechanics framework for untreated sand was first established using a series of drained and undrained (constant volume) tests, which served as a benchmark for evaluating the undrained cyclic liquefaction behaviour of untreated and biotreated sands. The results indicated that the modified initial state parameter ( ψ m 0 ) in DSS condition showed a good correlation with instability states and phase transformation under monotonic shearing. In undrained cyclic DSS loading condition, samples displayed cyclic mobility indicated by an abrupt accumulation of large strain or σ N 0 ′ transiently reaching zero or a sudden build-up of excess pore water pressure. The linkage between static and cyclic liquefaction was established for untreated and biotreated sand specimens based on the equivalence of characteristic soil states. The number of cycles before liquefaction (NL) for the biotreated sand specimens was mainly controlled by the cyclic stress ratio, e 0 , σ N 0 ′ and CC. For a similar initial state prior to undrained cyclic loading, the biotreated specimens required a larger NL compared to the untreated sand. The cyclic resistance ratio at NL = 15 (CRR15) increased with decreasing ψ m 0 for the untreated sand, while the CRR15 for biotreated sand increased with increasing CC and decreasing σ N 0 ′ . [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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44. Development of an Underwater Adaptive Penetration System for In Situ Monitoring of Marine Engineering Geology.
- Author
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Sun, Miaojun, Shan, Zhigang, Wang, Wei, Zhang, Shaopeng, Yu, Heyu, Cheng, Guangwei, and Liu, Xiaolei
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PORE water pressure , *SUBMARINE geology , *OFFSHORE wind power plants , *MARINE engineering , *ENGINEERING geology - Abstract
In recent years, offshore wind farms have frequently encountered engineering geological disasters such as seabed liquefaction and scouring. Consequently, in situ monitoring has become essential for the safe siting, construction, and operation of these installations. Current technologies are hampered by limitations in single-parameter monitoring and insufficient probe-penetration depth, hindering comprehensive multi-parameter dynamic monitoring of seabed sediments. To address these challenges, we propose a foldable multi-sensor probe and establish an underwater adaptive continuous penetration system capable of concurrently measuring seabed elevation changes and sediment pore water pressure profiles. The reliability of the equipment design is confirmed through static analysis of the frame structure and sealed cabin. Furthermore, laboratory tests validate the stability and accuracy of the electrical and mechanical sensor measurements. Preliminary tests conducted in a harbor environment demonstrate the system's effectiveness. [ABSTRACT FROM AUTHOR]
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- 2024
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45. Fabrication of vitreous carbon grid structures by carbonization of 3D printed parts for water-oil separation.
- Author
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Kim, Ju Wan, Kim, Chanwoo, Na, Hyunjin, Lee, Seongmin, Seok, Suyeon, Byeon, Seongyong, Kim, Young Kyu, and Kim, Seok-min
- Subjects
- *
PORE water pressure , *THREE-dimensional printing , *POROSITY , *CARBONIZATION , *DIGITAL printing - Abstract
An effective oil separating technique from water-oil mixture can be used in various industrial fields such as environmental purification and resource recycling. In this study, a vitreous carbon (VC) grid structure was fabricated by carbonization of digital light processing (DLP) 3D (3-dimensional) printed parts, and its oil separation performance was evaluated. A planner DVC grid structure with pore sizes of ∼200, ∼430 and ∼520 µm was fabricated and its water-oil separation performance werewas evaluated. Despite theoretical calculations suggesting adequate water repelling pressures for pores around ∼300 and ∼360 µm, actual performance fell short due to defects from 3D printing and carbonization processes. A more robust design approach involves fabricating a cuboid shell-shaped VC grid structure with smaller pores (∼150 µm), demonstrating continuous water-oil separation capabilities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Analytical and experimental study on shaking effects for improved stone column foundations.
- Author
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Arefpanah, Semko and Sharafi, Alireza
- Subjects
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STONE columns , *PORE water pressure , *WATERLOGGING (Soils) , *SANDY soils , *WATER boundaries - Abstract
Stone column technology is a method used to reduce liquefaction in saturated sediments. By using materials with greater permeability than the surrounding soil, stone columns can help drain excess pore water pressure and mitigate liquefaction potential during seismic loading. In this study, analytical solutions are proposed to address the liquefaction problem in saturated soils during earthquakes, taking into account the influence of stone columns and the surrounding soil. These solutions consider the excess pore water pressure at the boundary of the zones and analyze the vertical and horizontal drainages. The study also includes centrifuge tests on sandy soils improved with stone columns, calculating the total seepage flow and converting it into settlement based on the relationship between drainage flow rate and volumetric changes in the soil. The calculated settlement aligns well with the measured value in the centrifuge test, confirming the accuracy of the analytical formula for calculating settlement in stone column foundations. The study also evaluates the combined effects of radial and vertical drainages in stone column foundations using the derived analytical solutions. [ABSTRACT FROM AUTHOR]
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- 2024
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47. Mobility characteristics of rainfall-triggered shallow landslides in a forest area in Mengdong, China.
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Bingli, Hu, Lijun, Su, Chonglei, Zhang, Bo, Zhao, and Qijun, Xie
- Subjects
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NORMALIZED difference vegetation index , *PORE water pressure , *SOIL permeability , *LANDSLIDE hazard analysis , *LANDSLIDES , *SOIL cohesion - Abstract
The assessment of landslide susceptibility often overlooks the influence of forests on shallow landslide mobility, despite its significance. This study delved into the impact of forest presence on shallow landslide mobility during intense rainfall in Mengdong, China. Field investigations were coupled with the analysis of pre- and post-rainfall remote sensing (RS) images to delineate landslides. The ratio of landslide height (H) to travel distance (L) from a digital elevation model (DEM) were used to calculate landslides mobility. Preceding the event, forest coverage was evaluated using the normalized difference vegetation index (NDVI) derived from multiband RS image. The research identified 1531 shallow landslides in the area, revealing a higher concentration of landslides on slopes with elevated NDVI. Results indicated that disparities in soil permeability and cohesion, generating pore water pressure (PWP), triggered clusters of shallow landslides. Shallow landslides exhibit a higher propensity on slopes with elevated NDVI. The dimensions (height and area) of these identified shallow landslides typically exhibit a positive correlation with NDVI, consequently resulting in longer travel distances for landslides occurring on higher NDVI slopes. The average H/L ratio of all identified landslides was about 0.63. H/L generally increases with NDVI and decreases with landslide area. However, due to river channel restrictions, the H/L increases with slope gradient. The findings suggest that the high permeability of areas with tree roots poses a risk to the shallow stability of slopes, yet trees contribute to mitigating landslide mobility. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. A Unified Model of Cyclic Shear–Volume Coupling and Excess Pore Water Pressure Generation for Sandy Soils under Various Cyclic Loading Patterns.
- Author
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Chen, Guoxing, Qin, You, Wu, Qi, Gu, Xiaoqiang, and Juang, C. Hsein
- Subjects
- *
PORE water pressure , *SANDY soils , *CYCLIC loads , *STRAINS & stresses (Mechanics) , *WATERLOGGING (Soils) , *SHEAR strain , *SPECIFIC gravity - Abstract
Accurate prediction of excess pore water pressure (EPWP) generation in saturated sandy soils remains one of the most challenging issues in sandy site responses to strong earthquakes and extreme marine environments. This paper presents experimental results of undrained and drained multidirectional cyclic hollow cylinder (MCHC) tests on saturated coral sandy soils under various cyclic loadings. The results show that threshold generalized shear strain γga,th , below which EPWP and volumetric strain can be neglected, is an inherent property depending only on the soil type and initial state. Furthermore, there exists a virtually unique form of relationships between the generalized shear strain amplitude (γga) and the cumulative dissipated energy per unit volume of soil (Wc) at different relative density (Dr), irrespective of drainage conditions and cyclic loading conditions. These findings highlight the fundamental mechanism for cyclic deformation behavior and the uniqueness of correlations among rup (peak EPWP ratio), εvp (peak volumetric strain), and γga of saturated sandy soil at the similar Dr , regardless of cyclic loading conditions. Based on these findings, a novel unified model of γga -based cyclic shear–volume coupling and EPWP generation is established, which is independent of cyclic loading conditions over a wide loading frequency range. Then the applicability of the proposed model is validated by the experimental data of the same tested coral sandy soil and siliceous Ottawa sand, as well as the data of siliceous fine sands in previous work. It is found that the proposed model surpasses the existing strain- and stress-based models in accurately predicting EPWP generation under complex cyclic loadings, which can offer new insights into the mechanisms of the EPWP generation in saturated sandy soils. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Analysis of Offshore Wind Turbine by Considering Soil-Pile-Structure Interaction: Effect of Sea-Wave Load Duration.
- Author
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Massah-Fard, Maryam, Erken, Ayfer, Erkmen, Bülent, and Ansal, Atilla
- Subjects
- *
CYCLIC loads , *PORE water pressure , *SHEAR strain , *LATERAL loads , *FINITE element method - Abstract
Offshore Wind Turbines (OWTs) confront different types of environmental loads during their lifetime. One of the most significant loads is the cyclic sea-wave load which affects the OWT system during the approximate 25 years of design life. This lateral cyclic load can influence the response of the OWT system because of accumulated permanent displacement and excess pore water pressure generation in soil. This procedure can change pile-soil stiffness. However, the behavior of OWT and its foundations is mostly studied under short-term cyclic loading, and the effects of duration of the cyclic loads on pile-soil interaction and performance of the foundation are not well understood and documented. Therefore, there is a lack of guidance in codes for the duration effects of cyclic loads on the structural and geotechnical response of OWTs. In this regard, the current study considers the effects of duration of the cyclic loads on serviceability and performance of the OWT system by considering soil-foundation-structure interaction using a 2-D finite element method. The behavior of the OWT system is evaluated based on the internal forces and deformation of the monopile foundation, shear strain, and excess pore water pressure ratio in the surrounding soil. Besides, liquefaction susceptibility in the sandy soil layer at the vicinity of the monopile and its effect on the performance of the foundation is investigated. Finally, the results can provide guidance on estimation of the dynamic performance of the OWT system during long-term cyclic loads. They can be used to specify the need for consideration of the duration of cyclic lateral loads for the design of OWT structures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Effect of cyclic shear stress ratio on cyclic behavior of clay under multidirectional shear loading.
- Author
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Jin, Hongxu, Pan, Daoming, Guo, Lin, and Shi, Li
- Subjects
- *
PORE water pressure , *CYCLIC loads , *SHEARING force , *MODULUS of rigidity , *SHEAR strength - Abstract
In offshore engineering, soft clay foundations supporting infrastructure are subjected to significant multidirectional cyclic shear stresses due to earthquake or storm loads. To explore the undrained multidirectional cyclic behavior of foundation clays under critical loading conditions, a series of tests were conducted using a variable-direction dynamic cyclic shear system. By controlling the amplitude ratio (η) of two mutually perpendicular shear stresses in the horizontal plane, both unidirectional and multidirectional cyclic shear stress paths were achieved. The shear strength, stiffness, and pore water pressure are presented and discussed by considering the effects of η and cyclic stress ratio (CSR). The results suggest that the increase of CSR and η accelerates the cyclic failure, stiffness degradation, and pore water pressure accumulation of the clay specimens. An η-independent cyclic strength curve is established by normalizing the CSR to 0.755η. Although η hardly affects the shear modulus in the x direction (Gx) during the first cycle and at failure, it affects the parameter (χ) governing the shape of the stiffness degradation curve. Additionally, a model is proposed for predicting the evolution of normalized residual pore water pressure with respect to the number of cycles, wherein the parameter d remains unaffected by CSR and η. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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