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Landslides and other disaster problems caused by highway slope instability have a significant impact on people's lives, so the establishment of landslide prediction models is of great significance to the prevention and control of geological disasters. Long short term memory(LSTM) model based on Bayesian optimization algorithm (BOA) WAs proposed to investigate the effect of soil pressure changes on slope stability. The highway slope in Nanping City, Fujian Province was taken as an example. The correlation of multiple landslide influencing factors were integrated in the model, especially the time lag between each influencing factor, and the lag time was calculated. The four hyperparameters of the LSTM model ( time step, number of hidden elements, number of iterations, and batch size) were automatically searched and optimized, which solves the problem of needing to manually tune the parameters when building landslide prediction models with the LSTM model. To verify the accuracy and effectiveness of the model, the model was compared with recurrent neural network(RNN) and LSTM models, and the monitoring data set of soil pressure on highway embankments in Nanping City was used as a control. The results show that compared with the other two models, the mean square error(MSE), mean absolute error (MAE) and mean absolute percentage error(MAPE) of the BOA-LSTM model are reduced by 52. 4% and 59. 9%, 28. 8% and 30. 1%, and 30. 2% and 29. 9% respectively, and the prediction accuracy is improved from about 95% to 96. 56%, and the coefficient of determination is also closer to 1, indicating that the model can more accurately predict the earth pressure change and provide effective data support for slope deformation and stability analysis. [ABSTRACT FROM AUTHOR]

The use of a micropile group is an effective method for small and medium-sized slope management. However, there is limited research on the pile–soil interaction mechanism of micropile groups. Based on transparent soil and PIV technology, a test platform for the lateral load testing of slopes was constructed, and eight groups of transparent soil slope model experiments were performed. The changes in soil pressure and pile top displacement at the top of the piles during lateral loading were obtained. We scanned and photographed the slope, and obtained the deformation characteristics of the soil interior based on particle image velocimetry. A three-dimensional reconstruction program was developed to generate the displacement isosurface behind the pile. The impacts of various arrangement patterns and connecting beams on the deformation attributes and pile–soil interaction mechanism were explored, and the pile–soil interaction model of group piles was summarized. The results show that the front piles in a staggered arrangement bore more lateral thrust, and the distribution of soil pressure on each row of piles was more uniform. The connecting beams enhanced the overall stiffness of the pile group, reduced pile displacement, facilitated coordinated deformation of the pile group, and enhanced the anti-sliding effect of the pile–soil composite structure. [ABSTRACT FROM AUTHOR]

Soils containing swelling clays, such as montmorillonite, can develop significant pressures due to their water content, or can absorb significant surrounding water, leading to potentially dramatic volume changes. This work presents a generalized Terzaghi's stress principle that when rewritten in terms of measurable quantities, relates overburden pressure to volumetric change. In the limiting case of 100% clay it simplifies to the pressure-volumetric relationship developed by Phillip Low, and in the other extreme (no clay) Terzaghi's stress principle is obtained. The relationship is derived using Hybrid Mixture Theory, a multi-scale mixture theoretical framework, which allows for developing a more generalized mathematical model for multi-physics problems. The equation relating overburden pressure to volume incorporates the clay and water content, bulk liquid pressure, and four empirical constants. The resulting constitutive equation is validated against existing experimental data over a wide range of pressures and clay content. [ABSTRACT FROM AUTHOR]

Seepage damage is a significant factor leading to red mud tailings dam failures. Laboratory tests on seepage damage were conducted to investigate the damage characteristics and distribution laws of red mud tailings dams, including soil pressure, infiltration line, pore water pressure, dam displacement, and crack evolution. The findings revealed the seepage damage mechanisms of red mud slopes, offering insights for the safe operation and seepage damage prevention of red mud tailings dams. The results showed that the higher the water level is in the red mud tailings dam, the higher position the infiltration line is when it reaches the slope face. At the highest infiltration line point of the slope surface, the increase of pore water pressure is the highest and the change of horizontal soil pressure is the highest. Consequently, increased pore water pressure leads to decreased effective stress and shear strength, increasing the susceptibility to damage. Cracks resulting from seepage damage predominantly form below the infiltration line; the higher the infiltration lines is on the slope surface, the higher the position of the main crack formations is. The displacement of the dam body primarily occurs due to the continuous expansion of major cracks; the higher the infiltration lines are on the slope surface, the larger the displacement of the dam body is. [ABSTRACT FROM AUTHOR]

The tripod foundation (TF) is a prevalent foundation configuration in contemporary engineering practices. In comparison to a single pile, TF comprised interconnected individual piles, resulting in enhanced bearing capacity and stability. A physical model test was conducted within a sandy soil foundation, systematically varying the length-to-diameter ratio of the TF. The investigation aimed to comprehend the impact of altering the height of the central bucket on the historical horizontal bearing capacity of the foundation in saturated sand. Additionally, the study scrutinized the historical consequences of soil pressure and pore water pressure surrounding the bucket throughout the loading process. The historical findings revealed a significant enhancement in the horizontal bearing capacity of the TF under undrained conditions. When subjected to a historical horizontal loading angle of 0° for a single pile, the multi-bucket foundation exhibited superior historical bearing capacity compared to a single-pile foundation experiencing a historical loading angle of 180° under pulling conditions. With each historical increment in bucket height from 150 mm to 350 mm in 100 mm intervals, the historical horizontal bearing capacity of the TF exhibited an approximately 75% increase relative to the 150 mm bucket height, indicating a proportional relationship. Importantly, the historical internal pore water pressure within the bucket foundation remained unaffected by drainage conditions during loading. Conversely, undrained conditions led to a historical elevation in pore water pressure at the lower side of the pressure bucket. Consequently, in practical engineering applications, the optimization of the historical bearing efficacy of the TF necessitated the historical closure of the valve atop the foundation to sustain internal negative pressure within the bucket. This historical measure served to augment the historical horizontal bearing capacity. Simultaneously, historical external loads, such as wind, waves, and currents, were directed towards any individual bucket within the TF for optimal historical performance. [ABSTRACT FROM AUTHOR]

Utilizing a laboratory model test, this study seeks to evaluate the distribution patterns of volumetric moisture content, soil pressure, and pore water pressure within the body of a red mud dam, given varying initial conditions of slope types and ratios, during continuous heavy rainfall. The objective is to investigate the failure mechanisms of a red mud dam under distinct operational conditions during rainfall, thereby offering insights for landslide prevention and ensuring dam construction quality. The results suggest that a stepped red mud dam acts as a buffer platform, altering the seepage direction within the dam and minimizing the water seepage path. When the slope ratio is 1:1, the transient saturated zone is located on the slope face of the dam's body, near the top of the slope, with the saturation time at the first monitoring point occurring 300 s earlier than in a dam with a slope ratio of 1:2. Rainfall affects the distribution of internal forces in the red mud dam body. After rainfall, in the transient saturated zone of the stepped dam body, vertical soil pressure decreases 25% and horizontal soil pressure decreases 6.5%; in the transient saturated zone of the dam with a slope ratio of 1:1, vertical soil pressure decreases 14.8% and horizontal earth pressure decreases 29%; in the transient saturated zone of a dam with a slope ratio of 1:3, the change in soil pressure is small. [ABSTRACT FROM AUTHOR]

With the advancement of engineering techniques, underground shield tunneling projects have also started incorporating emerging technologies to monitor the forces and displacements during the construction and operation phases of shield tunnels. Monitoring devices installed on the tunnel segment components generate a large amount of data. However, due to various factors, data may be missing. Hence, the completion of the incomplete data is imperative to ensure the utmost safety of the engineering project. In this research, a missing data imputation technique utilizing Random Forest (RF) is introduced. The optimal combination of the number of decision trees, maximum depth, and number of features in the RF is determined by minimizing the Mean Squared Error (MSE). Subsequently, complete soil pressure data are artificially manipulated to create incomplete datasets with missing rates of 20%, 40%, and 60%. A comparative analysis of the imputation results using three methods—median, mean, and RF—reveals that this proposed method has the smallest imputation error. As the missing rate increases, the mean squared error of the Random Forest method and the other two methods also increases, with a maximum difference of about 70%. This indicates that the random forest method is suitable for imputing monitoring data. [ABSTRACT FROM AUTHOR]

The use of a micropile group is an effective method for small and medium-sized slope management. However, there is limited research on the pile–soil interaction mechanism of micropile groups. Based on transparent soil and PIV technology, a test platform for the lateral load testing of slopes was constructed, and eight groups of transparent soil slope model experiments were performed. The changes in soil pressure and pile top displacement at the top of the piles during lateral loading were obtained. We scanned and photographed the slope, and obtained the deformation characteristics of the soil interior based on particle image velocimetry. A three-dimensional reconstruction program was developed to generate the displacement isosurface behind the pile. The impacts of various arrangement patterns and connecting beams on the deformation attributes and pile–soil interaction mechanism were explored, and the pile–soil interaction model of group piles was summarized. The results show that the front piles in a staggered arrangement bore more lateral thrust, and the distribution of soil pressure on each row of piles was more uniform. The connecting beams enhanced the overall stiffness of the pile group, reduced pile displacement, facilitated coordinated deformation of the pile group, and enhanced the anti-sliding effect of the pile–soil composite structure.

The need to use such propulsion devices in mobile agricultural power units is substantiated. The relevance of this development based on global trends is shown. The purpose of the research is to develop the design, to evaluate strain-stress state and functional characteristics of undercarriages of agricultural tractors with replaceable half-tracks. An experimental design of the replaceable tracked undercarriage was developed and manufactured, modeling of loading modes was performed, calculations were carried out by the finite element method of the stress-strain state of structural elements according to 6 load schemes – tractor parking on a flat horizontal surface; movement with maximum traction force; parking across a 30° slope for the upper track; parking across a 30° slope for the lower caterpillar; driving into an obstacle with a deviation of 15°; driving over obstacles based on the central rollers. It was determined that the selected structural material, by the above mentioned loading modes ensure the operability of replaceable tracked undercarriage. Calculations were carried out to check the adequacy of the developed mathematical model using field tests in testing ground of FSAC VIM. It was determined that the maximum stress-strain state of the frame structure of a replaceable tracked undercarriage for all types of loading did not exceed 100 MPa. This provides a two-fold margin of safety in terms of fluidity of the structure, taking into account the characteristics of the selected material. In the maximum loaded state - parking across a slope of 30° - the highest stress on the upper track is 161 MPa, which corresponds to a safety margin of 1.45. The deformation of the bearing assembly was no more than 4 mm, which is allowed by the design of the drive assembly and the caterpillar.

The accurate estimation of the infiltration boundary of a buried point source is required in the hydraulic design of a subsurface drip irrigation (SDI) system, as well as in the numerical simulation of soil water movement. In this study, an experiment was conducted to measure the variation in emitter flow rate and soil back pressure in silty loam soil. The infiltration cavity was observed, and the radius was estimated by matching the measured emitter flow rate and soil back pressure using HYDRUS-2D simulations. The relationship between the cavity radius, emitter flow rate, and soil back pressure, as affected by the soil bulk density, working pressure, and nominal emitter flow rate, are discussed. The results indicate that the infiltration cavity formed rapidly during irrigation with an irregular shape. The surface area increased as nominal emitter flow rate increased and soil bulk density increased. The variation of flow rate as a function of time had no necessary relationship with that of soil back pressure, due to the formation of the cavity. When the infiltration process became stable, higher soil bulk density resulted in increase in soil back pressure and decrease in emitter flow rate. However, the effects of working pressure and nominal emitter flow rate on soil back pressure were unclear. The emitter flow rate and back pressure, solved by an existing analytical model using estimated radius, demonstrated satisfactory agreement with the measured data, with the minimum root-mean-square error (RMSE), compared with those using a constant radius. When the infiltration boundary was taken as a constant head, the soil back pressure and cavity both significantly affected the simulated soil wetting patterns. The effect of cavity radius on the wetting front could be neglected for the constant flux boundary.

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water inrush is one of the major disasters during tunnel construction. Due to its characteristics of great harm and difficult prediction, it has always been the focus of research. In order to reveal the mechanism of fault water inrush, a laboratory experiment is adopted to simulate tunnel excavation. The results show, firstly, the pore water pressure and soil pressure of model are unchanged before the fault is exposed; after the fault is exposed, the pore water pressure and soil pressure of vault decrease first, followed by the arch and haunch, and the decline of arch and vault is greater than that of haunch. Secondly, excavation has the greatest impact on the displacement of rock mass directly above the tunnel axis, and the farther away from the axis, the smaller the impact. Thirdly, the seepage channel around vault begins to expand, and clear water begins to seep out after the fault exposure. As the sediment in the crack is carried out by water flow, the clear water gradually becomes turbid, seepage channel changes from pore flow to fissure flow and then to pipe flow. Finally, Comsol is used to analyze the fault water inrush mechanism from the perspective of permeability change, and the correctness of model test is verified by comparing with engineering practice.

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the advancement of engineering techniques, underground shield tunneling projects have also started incorporating emerging technologies to monitor the forces and displacements during the construction and operation phases of shield tunnels. Monitoring devices installed on the tunnel segment components generate a large amount of data. However, due to various factors, data may be missing. Hence, the completion of the incomplete data is imperative to ensure the utmost safety of the engineering project. In this research, a missing data imputation technique utilizing Random Forest (RF) is introduced. The optimal combination of the number of decision trees, maximum depth, and number of features in the RF is determined by minimizing the Mean Squared Error (MSE). Subsequently, complete soil pressure data are artificially manipulated to create incomplete datasets with missing rates of 20%, 40%, and 60%. A comparative analysis of the imputation results using three methods—median, mean, and RF—reveals that this proposed method has the smallest imputation error. As the missing rate increases, the mean squared error of the Random Forest method and the other two methods also increases, with a maximum difference of about 70%. This indicates that the random forest method is suitable for imputing monitoring data.

Batter piles are often designed as foundation of high-rise structures to resist large lateral loads. The sizeable overturning moment of the superstructure will be transferred to the foundation so that batter piles are subject to the oblique uplift loading with changing directions. Due to the lack of understanding of the working behavior, the design and application of the oblique uplift batter pile are limited. In this study, 11 groups of laboratory tests are carried out in a testing box. The instrumental batter piles are made of polyvinylchloride pipes and loaded via pulley and counterweight. The variation of internal force, pile deformation, and load–displacement curve of the pile head is acquired. The load transfer mechanism and failure mode are summarized. A new type of tactile pressure sensor (TPS) is attached to the pile surface, and the actual pile–soil interaction forces in the normal direction are measured. The results show that the loading angle α controls the overall stability of the pile, the critical angle is 15° (in this study, qualitatively). When the α is within ±15°, the axial component of the oblique uplift load controls the overall stability of the pile; otherwise, the lateral component controls the stability. The increase of the loading angle α will increase both the bending moment of the negative and positive batter pile, but with different increments. The increase of pile inclination β will weaken the bending moment concentration effect. The soil pressure on the batter pile is in the offset state, which can be fitted by elliptic function. The pile–soil interaction below a certain depth is not affected by the pile inclination β and loading angle α. The middle to lower sections of the batter pile can be designed as the axial uplift pile, considering its resistance of axial skin friction only. This study shows the working mechanism of the oblique uplift batter pile in a manner way, which has practical significance for design and engineering application of batter pile. [ABSTRACT FROM AUTHOR]

The failure of treated slopes around the world, especially in China, is occurring at a noteworthy rate, resulting in an urgent requirement for post evaluation of the treated slopes; however, there is no mature technique established for post evaluation. By using a real loess slope treated by slope cutting in Shaanxi Province as the prototype, indoor geotechnical tests and model tests were performed to reveal the rainwater infiltration characteristics and pressure-varying characteristics inside the slope, the results of which were used to conduct a post evaluation of the slope in situ. The results mainly showed that the effect of rainwater scouring on the slope surface weakened gradually into a steady state at the end of the first year. The rainwater upon the slope surface preferentially infiltrated the platforms with gradually reducing rates; however, the observed wetting front cannot be regarded as the border between the unsaturated and saturated loesses. The soil pressures inside the slope did not increase, but decreased during the early period of rainfall. The displacements of key points mainly occurred during the first two years and then steady periods were entered. The above results were utilized to conduct a post evaluation of the slope prototype, by which a post evaluation framework was constructed. [ABSTRACT FROM AUTHOR]

• Proposed the deformed lining support method to reflect the soil-structure interaction in DEM simulations. • The distribution of fractures, force chains and displacements were analyzed to study the tunnelling induced soil stress redistribution. • The contact fabric around the tunnel was analyzed to study the block-mechanical behavior evolution of the arching effect. • The shape of soil arch was identified and the main differences between shallow and deep tunnels were summarized. During the construction of loess highway tunnels, large deformation caused major tunnel failure often occur, the large deformation is caused by the tunnelling induced strong stress redistribution within soils. Due to the limitation of simulation methods, the physical and mechanical changes of soils after the stress redistribution cannot be modelled. As a result, current modelling seldom reflects the change of soils and the interaction between the tunnel and the soil. In addition, the widely accepted Terzaghi's soil model cannot reflect the failure state of loess tunnels, and corresponding soil pressure calculation may lead to misleading results. In this study, a DEM based tunnel simulation method was employed to simulate the deformation of soils under the control of deformed lining, and two surrounding soil levels(Ⅳ and Ⅴ loess) and two buried depths (30 m and 100 m) were considered. The deformation behavior, stress state of soils, soil arch development and contact force fabric were analyzed, and the failure mode and calculation parameters in Terzaghi's soil pressure calculation method were modified for loess tunnels. Using the modified parameters, the calculated soil pressures, particularly for deep tunnels, reduced significantly and closely matched the soil pressures in both DEM simulations and in-situ measurements. [ABSTRACT FROM AUTHOR]

Advanced numerical models can be used to complement experimental results and further elucidate their findings. This is particularly true when certain scaled model "adjustments" are incorporated in the testing scheme to reduce the testing cost or schedule. This study conducts comprehensive finite element modeling to simulate large-scale shaking table tests conducted by Kim et al. (2023) [1] to evaluate the seismic performance of steel tunnels. The numerical model was calibrated by comparing its predictions with the experimental observations in the initial tests. The calibrated model was then validated by comparing its predictions with the results obtained from other test models and subjected to different input ground motions. The validated model was employed to comprehensively investigate the effects of the testing scheme parameters including the input motion time scaling, tunnel burial depth, and soil relative density. It was found that reducing the time scale factor during the tests led to decreased seismic responses. It was also found that the presence of overburden soil on top of the tunnel resulted in higher seismic bending moment values, and that higher overburden height increased both lateral and vertical soil pressures on the tunnel side walls and top slab. In addition, lateral soil distortion and tunnel deformations were found to be directly correlated with the overburden soil height. Furthermore, in the absence of overburden soil, there was a significant amplification in horizontal soil acceleration. The results demonstrated that lower-density sand bed experienced greater acceleration amplification and larger displacement, and the tunnel experienced larger lateral soil pressure and higher racking. Additionally, the results revealed that subjecting the same soil bed to several shaking tests affected its stiffness, and hence affected the test observations in the subsequent tests. This should be considered when planning shaking table tests. Finally, the strain values and racking ratios obtained from the numerical simulations and the shaking tests were in agreement with the values obtained from the FHWA procedure. • Used advanced models to simulate large-scale shaking tests, providing insights into steel tunnels' seismic performance. • Calibrated and validated numerical models against experimental data, ensuring accuracy in predicting seismic responses. • Investigated the effects of time scale factor, burial depth, and soil density on seismic responses. • Demonstrated overburden soil's impact on seismic bending moment, soil pressure, lateral displacement, and tunnel deformation. • Highlighted the amplification of horizontal soil acceleration without overburden soil and its impact on the tunnel behavior. • Studied sequential shaking effects on the soil beneath the tunnel, emphasizing soil stiffness degradation in test results. [ABSTRACT FROM AUTHOR]

Existing design models of soil pressure at the top of buried steel pipes are limited to small-diameter pipes. This study aims to investigate the behavior and design model on the soil pressure for large-diameter pipes considering the pipe diameter, diameter-to-thickness ratio, and cover depth. The distribution and size of soil pressure are obtained from finite element models and compared with traditional design models. Sensitivity studies of soil parameters, trench parameters, and friction coefficients are discussed. Furthermore, an innovative design model of soil pressure for large-diameter pipes is proposed. The results indicate that the basic distribution pattern of soil pressure is the “inverted basin”/parabola for large/small-diameter pipes, respectively. Peak soil pressure typically appears in the pleura of pipes with great flexibility and deep cover depth. The modulus and Poisson's ratio of backfill and soil-soil friction coefficient have an influence range of within 10% for soil pressure, while trench parameters have a more significant influence. Prism load is too large at high cover depth, and Marston load is small at low cover depth. The proposed basin model for soil pressure adopts the form of “straight line + parabola” for distribution and “Marston + pleura” load for size, with high accuracy and strong adaptability.

The foundation of offshore wind turbines is an important factor that determines their bearing capacity and service life. A theoretical analysis and model test of the bucket foundation with and without bulkheads at a scale of 1:150 are conducted in this study. The frequency-domain impedances of the two models were obtained and compared via cyclic loading tests at different frequencies. When the loading frequency was low, the absolute values of the real and imaginary impedances of the foundation model without a bulkhead in the frequency domain were higher than those of the foundation model with a bulkhead. Based on the analysis of the variation in soil pressure at the top of the bucket, it was found that the variation in soil pressure almost alternated with the cyclic load. The adsorption force is beneficial for the bearing capacity of a composite bucket foundation, making the structure safer. The impedance matrix of the foundation is determined by the size and shape of the foundation, mechanical parameters of the foundation medium, and frequency of the forced vibration. Wolf's lumped-parameter model was evaluated for applicability to analyse the bucket foundations with bulkheads. • A theoretical analysis and model test of the bucket foundation with and without bulkheads are conducted. • The frequency-domain impedances of the two models are obtained and compared via cyclic loading tests at different frequencies. • The adsorption force is beneficial for the bearing capacity of a composite bucket foundation, making the structure safer. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Featured Application: The interaction between the soil and underground granary subjected to water buoyancy, especially the recommendatory floating water level, is useful for the design and popularization of underground granaries. The buoyancy of underwater can cause the underground granary to overall float, or even overturn, and the interaction between the soil and underground granary is the key to its stability. This paper introduces a non-contact experiment system utilizing the digital image correlation (DIC) technology and particle image velocity (PIV) technology, and its measurement accuracy is analyzed. Then, this system is employed to study the granary displacement and the soil deformation around the granary subjected to the buoyancy of water. Results show that with the increase of the degree of compaction of the soil around the granary, the floating water level increases by 10.77% and the vertical displacement decreases by 17%. When the soils around the granary are loose sands, the soil deformation range shows an obvious inverted triangle. When the soils are medium dense sands, the soil deformation zone concentrates at the junction of the conical granary bottom and granary wall. When the soils are dense sands, the disturbed range of the soil obviously reduces, and the soil deformation concentrates on both sides of the granary wall and is distributed symmetrically. Finally, taking the medium dense sands around the granary as an example, the reasons for the unstable failure of the granary subjected to buoyancy are discussed, assisted by the soil pressure theory of retaining wall. With the granary increasingly inclining, the soil deviating from the inclined direction of the granary loses its support, which drives the soils to reach the active limit state. The soil in the inclined direction of the granary is squeezed, resulting in passive soil pressure on the granary wall. The soil deformation increases continuously to a passive limit equilibrium state, and the soil continuously develops a sliding surface, resulting in the unstable failure of the granary. This research is expected to provide the technical guidance for the design and popularization of underground granaries. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An increase in the power of the high-clearance tractor with the 3K2 wheel configuration (TTZ-811) and the weight of the machines coupled with it has led to an increase in the pressure of its running elements on the soil. The authors have proposed to replace it with a tractor with the 4K2 wheel configuration with an adjustable ground clearance (TTZ-1033), which has several advantages.Research purpose The study of the effect of the wheel configuration, travel speed and air pressure in the tire on the tractor's front wheel pressure on the soil.Materials and methods The authors have analytically determined the relationship between the contact area of a wheel tire with the soil on the tire parameters and the internal air pressure in it. To take measurements, load TAS607 sensors like with specially made nozzles have been used.Results and discussion It has been found that under similar conditions, the average pressure on the soil in the layer of 10-50 centimeters across the width of the front wheel tire of TTZ-811 is 19.0-27.6 kilopascals more as compared to TTZ-1033. It has been found that an increase in air pressure in the tire from 1.2 to 2.2 megapascals results in a n increase in average front wheel pressure on the soil in the seed layer (0-10 centimeters) of the TTZ-1033 tractor from 61.9 to 70.8 kilopascals, and of the TTZ-811 tractor – from 63.5 to 79.3 kilopascals. It has been revealed that at a depth of 10 centimeters, the pressure of the front wheel of the TTZ‑1033 tractor averaged 84.9-108.2 kilopascals, and at a depth of 50 centimeters – only 12.2-12.8 kilopascals. Under the same conditions, the average pressure` of the TTZ-811 tractor's front wheel decreases from 78.0-113.3 to 15.3-52.8 kilopascals.Conclusions The authors have stated that soil compaction with the front wheels of a tractor can be reduced by replacing a tractor with a 3K2 wheel configuration with a tractor with a 4K2 wheel configuration, as well as by increasing the tractor speed.

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Large-diameter buried steel pipes (BSPs) have been widely utilized in water diversion and hydropower fields. This paper presents a comprehensive numerical investigation on the interaction between the large-diameter pipe and soil under three typical working conditions, to capture the structural mechanical behaviors of pipe deformation, soil displacement, and soil pressure. Furthermore, a parametric analysis of pipe diameter is conducted, along with the sensitivity study of soil parameters based on the orthogonal test method. The results show that the water weight increases the pipe deformation significantly by 14%, while the high internal water pressure decreases the deformation greatly with the maximum effect of 39%. The pattern of soil pressure at the top of the pipe changes from parabola to double-hump as the pipe diameter varies from 0.5 m to 5.0 m. The pipe deformation and soil pressure keep increasing with the pipe diameter, but the safety margin for prism load decreases gradually. Pipe deformation and soil pressure are very sensitive to the elastic modulus and Poisson's ratio of backfill. Friction coefficients of soil-soil (trench sidewall) and pipe-soil have great influences on the soil pressure, while the bedding material and backfill cohesion have small effects on it. [ABSTRACT FROM AUTHOR]

The article presents a methodology for the theoretical assessment of the processes of loosening and compaction of the soil with a working tool based on pressure distribution patterns in the soil stratum obtained using the computational fluid dynamic model (CFD model). A computational fluid dynamics model is developed to assess the stress-strain state of the soil and soil particles' movement, implemented in the FlowVision computer program. As a model, the FlowVision "Free Surface" model is adopted, in which the Navier-Stokes equations, the transfer equations of turbulent functions, and the transfer equation for the filling function are solved. The implementation of this model made it possible to establish three-dimensional pressure distribution patterns, based on which zones of deformation, loosening, and compaction in the soil were determined in interaction with a vertical working tool. The implementation of this methodology will theoretically justify the geometric parameters of tillage tools and machines, taking into account the conditions for forming the required quality of tillage by loosening and compaction. [ABSTRACT FROM AUTHOR]

Considering the change of earth pressure of foundation pit envelope under different displacement, the calculation method of stress release coefficient β on the sidewall of the foundation pit is derived. Based on the Mindlin stress formula, a comprehensive 'equal-generation soil pressure coefficient K' is introduced with the consideration of the substratum of the foundation soil. The formulas for calculating the horizontal displacement, interring stagger, rotation angle and shear force of adjacent subway tunnels caused by the excavation of the side-side foundation pit and the displacement of the retaining deduced. What' s more, two engineering examples are selected for verification. The results show that: when the displacement of the building envelope reaches the active limit state, the earth pressure of the building envelope is classified as the active soil pressure; β reaches the limit value at the same time. Nevertheless, the displacement of the building envelope cannot reach the limit value in practical engineering, thus the earth pressure should be between the static earth pressure and the active earth pressure. The physical meaning of f3 is given in this paper. Moreover, the corresponding displacement and earth pressure of the building envelope can be calculated according to the displacement of the tunnel by analyzing the β value inversely. The values of β in different sections during the excavation of foundation pit and in a different sequence are set to be varied. The spatio-temporal effect is considered in this paper to obtain the influence of tunnels in different foundation pit excavation schemes. [ABSTRACT FROM AUTHOR]

A simplified equation, which allows for the calculation of the tension force using the actual tube height and pumping pressure with the flexibility to use a coefficient of lateral pressure (K), is proposed and validated theoretically by comparing the proposed method with two well-known methods in the literature, and experimentally, by conducting several half cross-section tests. The half cross-section test proposed in this study is unique and configured in such a way that the top and bottom of the geotextile tube is supported by load cells to be able to quantitatively measure the maximum tension force, as well as the stress and strain of the geotextile tube. With the use of the simplified equation, the actual field conditions can be exceptionally represented, making it more advantageous over the previous methods. [ABSTRACT FROM AUTHOR]

The accurate estimation of the infiltration boundary of a buried point source is required in the hydraulic design of a subsurface drip irrigation (SDI) system, as well as in the numerical simulation of soil water movement. In this study, an experiment was conducted to measure the variation in emitter flow rate and soil back pressure in silty loam soil. The infiltration cavity was observed, and the radius was estimated by matching the measured emitter flow rate and soil back pressure using HYDRUS-2D simulations. The relationship between the cavity radius, emitter flow rate, and soil back pressure, as affected by the soil bulk density, working pressure, and nominal emitter flow rate, are discussed. The results indicate that the infiltration cavity formed rapidly during irrigation with an irregular shape. The surface area increased as nominal emitter flow rate increased and soil bulk density increased. The variation of flow rate as a function of time had no necessary relationship with that of soil back pressure, due to the formation of the cavity. When the infiltration process became stable, higher soil bulk density resulted in increase in soil back pressure and decrease in emitter flow rate. However, the effects of working pressure and nominal emitter flow rate on soil back pressure were unclear. The emitter flow rate and back pressure, solved by an existing analytical model using estimated radius, demonstrated satisfactory agreement with the measured data, with the minimum root-mean-square error (RMSE), compared with those using a constant radius. When the infiltration boundary was taken as a constant head, the soil back pressure and cavity both significantly affected the simulated soil wetting patterns. The effect of cavity radius on the wetting front could be neglected for the constant flux boundary. • High nominal discharge and soil bulk density enlarge the infiltration cavity of an SDI emitter. • Change of emitter discharge with time is independent of that of soil back pressure. • Cavity radius affects emitter discharge, soil back pressure, and soil wetting patterns. • Models were proposed to predict cavity radius, emitter discharge, and soil back pressure. [ABSTRACT FROM AUTHOR]

The seismic design of metro stations relies on the accurate assessment of the magnitude and distribution of seismic soil pressures. Seismic soil pressure (SSP) is an important load acting on the side walls of metro stations and its magnitude and distribution shape have been one of the hot topics of research in the field of seismic resistance. In view of this, a shaking table test on a soil-metro station model under different seismic excitations was carried out, where SSP data were collected from the side walls and a residual was introduced to quantify the deviation of the test values from the analytical values. The results show that: (i) the difference between the absolute values of the SSPs along the left and right side walls at same burial depth and time is small, with one tension and one compression. (ii) The time history of the SSP along the side walls has periodic characteristics and first-order predominant frequency of SSP is consistent with that of the ground. (iii) The widely used analytical equations do not reflect the actual situation of the SSP along the side walls of the metro stations. • The distribution of seismic soil pressures in one period is firstly presented for underground metro station. • Seismic soil pressures based on shaking table tests are compared with several existing analytical solutions. • Residual is introduced to quantify the deviation of measured seismic soil pressures from analytical ones. [ABSTRACT FROM AUTHOR]

The buoyancy of underwater can cause the underground granary to overall float, or even overturn, and the interaction between the soil and underground granary is the key to its stability. This paper introduces a non-contact experiment system utilizing the digital image correlation (DIC) technology and particle image velocity (PIV) technology, and its measurement accuracy is analyzed. Then, this system is employed to study the granary displacement and the soil deformation around the granary subjected to the buoyancy of water. Results show that with the increase of the degree of compaction of the soil around the granary, the floating water level increases by 10.77% and the vertical displacement decreases by 17%. When the soils around the granary are loose sands, the soil deformation range shows an obvious inverted triangle. When the soils are medium dense sands, the soil deformation zone concentrates at the junction of the conical granary bottom and granary wall. When the soils are dense sands, the disturbed range of the soil obviously reduces, and the soil deformation concentrates on both sides of the granary wall and is distributed symmetrically. Finally, taking the medium dense sands around the granary as an example, the reasons for the unstable failure of the granary subjected to buoyancy are discussed, assisted by the soil pressure theory of retaining wall. With the granary increasingly inclining, the soil deviating from the inclined direction of the granary loses its support, which drives the soils to reach the active limit state. The soil in the inclined direction of the granary is squeezed, resulting in passive soil pressure on the granary wall. The soil deformation increases continuously to a passive limit equilibrium state, and the soil continuously develops a sliding surface, resulting in the unstable failure of the granary. This research is expected to provide the technical guidance for the design and popularization of underground granaries.

According to indoor model test, we research the deformation mechanism of the interaction of soils of expanding belled pile group under the horizontal load. The embedded soil sensor measures the soil pressure between pile side to convert the pile body stress and bending moment, and analyzes the variation law of pile-soil interaction. Combined with finite element software,the calculation model of various piles is established to study the influence law of pile length and pile-soil interaction. The research results of this paper provide a strong scientific basis for the theoretical development of the expanding belled pile foundation and engineering application. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bucket-based structure is a new structure developed according to the actual needs of silty coast engineering construction. The variation of soil pressure inside and outside the bucket is studied through in-situ test under the condition of unilateral backfilling. Through data analysis, the variation law of soil pressure of bucket-based structure and the failure state of different soil layers under backfilling load are obtained. The measured data show that the silt is damaged under the backfilling load, the soil pressure calculation is not in conformity with the classical soil pressure calculation theory, clay is not damaged under backfilling load, soil pressure calculation can adopt the classical soil pressure calculation theory, at the same time, the measured data show that the soil pressure balance can be used to estimate the bucket stability. The conclusions of this paper can provide reference for the optimization of the bucket-based structure stability calculation method. [ABSTRACT FROM AUTHOR]

A series of large-scale model tests was conducted on compaction-grouted soil nails to study the influence of the degree of saturation on the soil response to compaction grouting and pull-out. The experimental results show that the initial degree of saturation of the soil strongly influences the grout injectability, thus the formed diameter of grout bulb. Subsequently, the diameter of the grout bulb alters the pull-out force, with larger grout bulbs generating higher pull-out forces and exhibiting greater hardening behaviour. Interestingly, the initial pull-out forces are the same for the same grouting pressure, regardless of the initial degree of saturation and the subsequently grout bulb. In addition, some of the main factors influencing the pressure grouting and pull-out of the soil nail, as the initial degree of saturation varies, are as follows. First, the variations in the soil pressure and density with the initial degree of saturation are similar to that of the volume of grout injected, and the compression of the soil induced by pressure grouting exhibits a similar evolution with the initial degree of saturation at different locations. Second, the initial degree of saturation of the soil sample plays a dominant role in the change in suction during pressure grouting and pull-out of soil nail. Third, the horizontal soil pressure derived from the pull-out of soil nail propagates closely in the soil sample of lower initial degree of saturation. The vertical soil pressure induced by the vertical soil dilation and squeezing effect varies in accidence with the initial degree of saturation and the grout bulb. [ABSTRACT FROM AUTHOR]

Reinforced subgrade has been increasingly used in highway and railway industries. Deformation failure of reinforced subgrade in the long-term operation has become a challenge against roadbed construction and maintenance. Static load of pavement is the key factor that influences stability of reinforced subgrade. The deformation law of reinforced subgrade and soil pressure distribution laws under staged static loads of pavement were analyzed by a laboratory large-scale model (4:1) test to reveal the influences of pavement static load on reinforced subgrade. Research results demonstrate that horizontal and vertical deformations of panel increase with static loads. Development loads of subgrade bearing capacity can slightly influence deformation after filler compaction, indicating that influences of static loads on subgrade deformation are closely related with the degree of filler compaction and rebar-soil interaction. Static loads of pavement considerably influence horizontal and vertical earth pressures at the subgrade top but slightly affect deep roadbeds. This outcome reflects that reinforcement accelerates attenuation of additional stress. The increased static loads of pavement slightly influence the strain state of subgrade geogrids. Distribution and value of geogrid strain in subgrade remain the same with the increase in static loads. This finding reveals that the formation of geogrid strain occurs during filling construction of subgrade. The compaction quality of filler can considerably influence the strain of geogrids. In summary, the influences of pavement static loads on reinforced subgrade are related to compaction quality during filling. Controlling the compaction degree of subgrade is the key to preventing deformation during the operational period. Research conclusions can provide theoretical references to control engineering diseases of reinforced subgrade and offer references to the construction of reinforced subgrade. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University / Shanghai Daxue Xuebao is the property of Journal of Shanghai University (Natural Sciences) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)