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The Niigata M7.5 Earthquake of 1964 remains uniquely important among field case histories for understandingliquefaction triggering and manifestations. Much has been written about the Kawagishi-cho strong motion record, theNiigata case histories of seismic-soil liquefaction triggering, and the post-triggering lateral spread displacements. Thispaper explores a new and different perspective on the disaster - the geologic setting and geomorphic processesreworking Holocene sand units that ultimately create the most severe liquefaction effects during the earthquake. Acrossthe city, liquefaction was most pronounced in fluvially-reworked sands derived from three aeolian and barrier islanddune fields upriver and along the coastline. The largest source of beach and aeolian sand material that liquefied in1964 is a mid-Holocene maximum transgressive barrier island that deposited fifty–sixty meters of sand along the thencoastline five-eight-thousand years ago. Tectonic-downwarping and -subsidence of the Echigo Plain has allowed fordelta-progradational processes to build out a thick sedimentary prism beneath the current location of Niigata City.Within this prism, the Shinano and Agano Rivers have eroded and fluvially-redeposited these barrier island sands, andthose of a closer-in two-three-thousand-year beach-ridge deposit, beneath districts of the city. Most recently, forhuman-placed fills the materials are sourced almost entirely from modern coastal beach-ridge and sand dune depositsfronting the Sea of Japan. More than any other factors, these geologic conditions and geomorphic depositional historiescontrolled the locations and severity of soil liquefaction during the 1964 event. Today, these geologic units persist asa future risk to infrastructure of Niigata City.

The shapes and morphological features of grains in sand assemblies have far‐reaching implications in many engineering applications, such as geotechnical engineering, computer animations, petroleum engineering, and concentrated solar power. Yet, our understanding of the influence of grain geometries on macroscopic response is often only qualitative, due to the limited availability of high‐quality 3D grain geometry data. In this paper, we introduce a denoising diffusion algorithm that uses a set of point clouds collected from the surface of individual sand grains to generate grains in the latent space. By employing a point cloud autoencoder, the three‐dimensional point cloud structures of sand grains are first encoded into a lower‐dimensional latent space. A generative denoising diffusion probabilistic model is trained to produce synthetic sand that maximizes the log‐likelihood of the generated samples belonging to the original data distribution measured by a Kullback‐Leibler divergence. Numerical experiments suggest that the proposed method is capable of generating realistic grains with morphology, shapes and sizes consistent with the training data inferred from an F50 sand database. We then use a rigid contact dynamic simulator to pour the synthetic sand in a confined volume to form granular assemblies in a static equilibrium state with targeted distribution properties. To ensure third‐party validation, 50,000 synthetic sand grains and the 1542 real synchrotron microcomputed tomography (SMT) scans of the F50 sand, as well as the granular assemblies composed of synthetic sand grains are made available in an open‐source repository. [ABSTRACT FROM AUTHOR]

In infrastructure planning and construction, modeling the subsoil and its associated uncertainty is a fundamental task of geotechnical engineers. However, probabilistic methods and tools for quantifying and displaying the uncertainty of the subsoil models are rarely used in practice where deterministic interpolation dominates. In digital planning using Building Information Modeling (BIM), the probabilistic approach supports creating a discipline model in which the uncertainties of the spatial layer structure are statistically quantified to evaluate the georisks in the design and execution of civil constructions. This article presents a case study using a combination of Sequential Gaussian Simulation (SGSIM) and Sequential Indicator Simulation (SISIM) to account for uncertainties in soil layer geometry. In a case study at the Munich Town Hall, a geostatistical approach is applied and validated based on 70 bore logs, whereby the probabilities for the occurrence of a particular layer are spatially quantified. The case study illustrates the methodology‘s great potential and benefits compared to the conventional deterministic approach based on interpolation procedures. [ABSTRACT FROM AUTHOR]

Tensile and shear failure are the main damage modes of rocks in geotechnical engineering. To investigate the energy evolution and failure characteristics of coarse-grained sandstone during pure mode I/II loading, loading-unloading tests were performed on cracked straight-through Brazilian discs (CSTBD) with different unloading levels (i), and its acoustic emission (AE) signals and microstructure were monitored. The results show that the AE signals of the CSTBD are negligible before the peak load (Mode I), or appear when the axial load exceeds a stress threshold and then increases significantly before the peak load (Mode II), and the Kaiser effect was observed in the second loading stage. The specimens’ input, elastic and dissipative energies varied quadratically with i. The elastic energy is always greater than the dissipative energy (Mode I), whereas the dissipative energy exceeds the elastic energy at i < 0.5 (Mode II). The crack propagation paths start from the crack tip and extend rapidly and straightly (Mode I) or slowly in the form of wing crack (Mode II) to the loading point. The microstructures of the specimens are mainly intergranular fracture (mode I) and transgranular fracture (mode II). The results provide references for studying energy evolution and failure mechanisms of rocks under mixed modes I+II/I+III loading. [ABSTRACT FROM AUTHOR]

Surface-projected piles, such as helical and under-reamed piles, are widely utilized in geotechnical engineering to enhance the load-carrying capacities of pile structures with surface projection part. Despite the use of a wide variety of surface-projected conditions, detailed investigations considering various dimensions and angles of surface-projected piles remain limited in the current literature. This study aims to assess the effects of surface-projected widths wp (10 mm, 20 mm, 40 mm) and angles θ (18°, 27°, 45°, 90°) on pile penetration resistance using a two-dimensional model and PIV analysis. Wider projections increased resistance, with a maximum of 1.84 kN—57% higher than conventional piles in the model ground. Penetration resistance was proportional to width at 90°; for wp = 20 mm, penetration resistance decreased with increasing θ, while for wp = 40 mm, it increased. Theoretical ultimate bearing capacity calculations emphasize differences from experimental results due to neglected shaft friction. Residual penetration resistance and particle displacement were observed for wp of 20 mm and 40 mm after failure. This study provides insights into optimizing surface-projected pile design and understanding ground failure mechanisms. [ABSTRACT FROM AUTHOR]

Handling geotechnical peculiarities in specialized ground models – an experience report Dr. Spang GmbH has developed numerous specialized ground models in recent years and has gained corresponding experience in ground modeling. Within the company, a standard procedure for creating these specialized models has been established. From a software perspective, automatic meshing (triangulated 3D surface mesh of the layer boundaries) already delivers useful results for many standard cases. However, in geotechnics, there are not only standard cases and features to assess. Geotechnical peculiarities (e. g. inhomogeneous layering) result in an increased manual modeling effort. This article aims to shed light on how to handle these peculiarities in modeling, present the additional modeling steps involved, and highlight the software limitations that arise in automatic meshing (interpolation or triangulation) in such special cases. [ABSTRACT FROM AUTHOR]

Enzymatically induced carbonate precipitation (EICP) is widely studied as a promising technique for soil stabilization and cementation. The solidification inhomogeneity resulted from higher urease activities always hampers the wide application of EICP. To date, several methods have been developed to effectively improve the solidification homogeneity at temperatures below 60 °C; however, several practical application fields have a higher environmental temperature over 60, even reaching 75 °C. The higher urease activity and quick decay at these temperatures easily result in solidification inhomogeneity and eventually lower strengths. In this study, the combined addition of garlic extract (GE) and dithiothreitol (DTT) was proposed to solve the problem. The influence of the proposed method on urease activities and production rates for calcium carbonate (CaCO3) was investigated and the sand solidification test was conducted to further study the influence of the method on treatment effects. Results showed that the urease activity significantly decreased with the GE addition, while the urease activity increased after the DTT addition, regardless of temperatures. With a higher content of DTT, both the increasing ranges of urease activities and production rates for CaCO3 were larger. In the sand solidification test, the GE addition decreased the precipitation rate of CaCO3 at high temperatures, which was beneficial to obtain smaller differences in sonic time values and CaCO3 contents at different parts of sand columns. Subsequently, the DTT would recover urease activity to ensure a sufficient produced amount of CaCO3 and to achieve higher strength. The optimum contents of GE and DTT were different for the samples solidified at different temperatures. The proposed method had significant application potential in the fields of geotechnical and materials engineering. [ABSTRACT FROM AUTHOR]

In contrast to cemented soils in terrestrial natural environments, cemented soils in littoral and marine geotechnical engineering face numerous difficulties. In coastal and marine geotechnical engineering, cemented soils are frequently degraded by ion erosion, tidal scouring, and temperature variations. Long-term marine environments present numerous challenges for cemented soil foundation projects. In marine geotechnical engineering, addressing and enhancing these degradation issues has become a crucial topic. To address this engineering problem, Nano-SiO2 is added to cement-stabilized soils to enhance their engineering performance. To investigate the mechanical effects and erosion mechanisms of Nano-SiO2 cemented soil subjected to chloride ion erosion and tidal alternation scouring, laboratory experiments, including immersion erosion tests with sodium chloride solution and dry-wet cycle tests, were designed. On specimens subjected to dry-wet cycles after chloride ion erosion at varying concentrations, unconfined compressive strength tests (UCS), X-ray diffraction (XRD) experiments, and scanning electron microscopy (SEM) were performed. The objective was to investigate the impact of chloride ions and Nano-SiO2 on the microstructure and strength of cemented soil. Adding 2.5% Nano-SiO2 can promote cement hydration reactions while preventing the entry of chloride ions into the cemented soil, thereby increasing the density and compressive strength of the cement. [ABSTRACT FROM AUTHOR]

The pullout capacity of horizontal anchor plates plays a crucial role in ensuring the stability and performance of various structures subjected to uplift or lateral loading. This paper presents an investigation into the pullout capacity of horizontal anchor plates using the method of stress characteristics. The method offers a simplified analytical approach that allows for quick estimations and insights into the stress distribution and failure mechanism of anchor plates. The study focuses on circular anchor plates with varying embedment ratios, considering different soil friction angles. Through computational analyses and the generation of characteristic grids, the behavior and stress distribution of anchor plates are examined. The results are compared with several experimental data from the literature to validate the applicability of the method. The findings provide valuable insights into the influence of embedment ratios and soil friction angles on the pullout capacity of horizontal anchor plates. This research contributes to the understanding of anchor plate behavior and offers a practical tool for assessing their performance in geotechnical engineering applications. [ABSTRACT FROM AUTHOR]

Tensile cracks significantly influence stability of mining, tunneling, and other geotechnical engineering scenarios. Discontinuous deformation analysis (DDA) is widely employed to analyze, predict, and prevent the deformation and progressive failure of such geomaterials. However, an accurate and efficient simulation of the cracking process remains a challenge, requiring appropriate fracture models. This study presents an improved DDA algorithm featuring a nonlinear cohesive zone model (CZM) designed for the intricate deformation and fragmentation analysis of geotechnical structures composed of quasi-brittle materials. Building upon fracture mechanics theory, an exponential-type CZM that accounts for both post-peak softening behaviors and nonlinear relations inherent in quasi-brittle materials is introduced. This exponential-type CZM is integrated into the original DDA method, addressing the co-edge blocks connected with cohesive springs. The ensuing unbalanced force in normal contact arising from the nonlinear cohesive spring is mitigated using a nonlinear iterative algorithm. The formulation, the implementation, and the iteration of the exponential-type CZM within the DDA framework are elucidated. Finally, the feasibility and the accuracy of the improved DDA for analyzing quasi-brittle crack propagation are demonstrated and validated by comparing several examples with experimental and numerical results. Highlights: An improved DDA, incorporating an exponential-type CZM, is presented to simulate the nonlinear fracture behaviors in geomaterials. A nonlinear iterative algorithm is proposed to address the solution of nonlinear equilibrium equations in the improved DDA. The effectiveness and the accuracy of the improved DDA are validated and verified through typical examples. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of crack propagation and failure behavior in rocks is fundamental for geotechnical engineering and mining applications. This study employs a coupled damage model based on the Smoothed Particle Hydrodynamics (SPH) method that integrates the Drucker–Prager and Grady–Kipp models. This mixed failure model is then implemented to simulate the crack propagation morphology and failure modes in uniaxial compression tests of flawed rock samples, and validated against multiple experimental observations. The numerical results exhibit good agreement with experimental observations from the literature in terms of the initiation and propagation of tensile and shear fractures, as well as the final failure morphology. Additionally, this work incorporates contact algorithms to simulate the loading plates, thereby better representing the actual experimental conditions encountered in uniaxial compression tests. Furthermore, a comprehensive parametric study is conducted to investigate the influence of key factors, such as pre-flaw geometry, cohesion, friction at the loading plate interface, and discretization parameters, on the simulated fracture processes and mechanical response. The outcomes indicate the proposed coupled damage model within the SPH framework can accurately capture complex fracture patterns and failure mechanisms in uniaxial compression of flawed rocks. This work demonstrates the capability of the SPH-based mixed-mode failure model to provide insights into rock fracture and failure mechanisms. Highlights: A coupled damage model integrating the Drucker–Prager and Grady–Kipp criteria within a smoothed particle hydrodynamics (SPH) framework is applied to simulate both shear and tensile failure modes in rocks firstly. The model is validated against more experimental observations, demonstrating the model's ability to reproduce the crack propagation and characteristic stress–strain behavior. This work presents a comprehensive parametric study investigating the influence of key factors, such as pre-flaw geometry, cohesion, friction at the loading plate interface, and discretization parameters, on the simulated fracture processes and mechanical response. These systematic investigations provide valuable insights into the governing mechanisms and highlight the importance of proper model calibration for accurate predictions. This work incorporates contact algorithms to simulate the loading plates, thereby better representing the actual experimental conditions encountered in uniaxial compression tests. The tensile wing cracks subjected to uniaxial compression, oriented vertically towards the top boundary of the specimen, are successfully captured. [ABSTRACT FROM AUTHOR]

This paper forms part of the SINEW (sinkhole early warning) project and continues the work conducted by Möller and co-workers in 2022, where 1g experiments demonstrated the feasibility of using distributed fibre-optic sensing (DFOS) for sinkhole early warning. Their experimental campaign highlighted an order of magnitude difference in the strain between the soil and the cable that remains unexplained and weakens confidence in the technology and/or the experimental method. This paper uses three-dimensional finite-element analyses to examine further this discrepancy and the soil–cable interface. The results support the experimental findings and demonstrate that the DFOS signature strain profile is induced by the horizontal movement of the ground, and enhanced when sufficient coupling at the soil–cable interface is achieved. This result holds when modelling is scaled to realistic confining pressure, and its significance is twofold. First, this needs to be accounted for in the DFOS laying technique. Second, particles of cohesionless soils undergo relatively high horizontal displacement away from the centre of the sinkhole, and this means that DFOS cables are able to detect subsidence away from the centre of the sinkhole. The paper illustrates this result and the signature strain profile expected in this case. [ABSTRACT FROM AUTHOR]

Understanding the dynamic behavior of poroelastic soil adjacent to an axially vibrating pile is crucial to the seismic design and vibration reduction of various geotechnical engineering projects; however, few analytical studies exist on this issue to this point. In this study, to obtain the dynamic response of fully saturated soil around and beneath a vibrating pile, the solving scheme of the pile-fictitious soil pile (FSP) coupled model is extended to the pile-porous FSP coupled model and surrounded by multiple poroelastic medium layers with finite thickness. The semianalytical solutions of the pile-porous FSP-saturated soil-coupled vibration system are resolved and verified by existing solutions under different degradation situations. The developed model and the solutions are then employed to investigate the wave propagation mechanism in the fully saturated soil. The results show a certain degree of hysteresis in the fluid phase response during the vibration. As the permeability of the poroelastic material decreases, the hysteresis effect of the fluid phase relative to the solid phase weakens, resulting in an increase in excess pore-fluid pressure and a wider range of influence from the vibration. The conclusions derived from this study can also provide practical guidance for pile testing techniques, such as the parallel seismic (PS) method and low-strain pile integrity test (PIT) onsite. [ABSTRACT FROM AUTHOR]

For the characterization of fiber-reinforced soil under static loading conditions, there is a wealth of literature. However, study on the dynamic behavior of fiber-reinforced soil is very limited. Now that earthquakes are occurring frequently around the world, the dynamic soil analysis has become important for all classes of geotechnical engineering problems. Through numerical simulation of triaxial specimens, the current study explores the behaviour of fiber-reinforced cohesionless soil. The numerical model was validated using existing laboratory triaxial compression testing literature. The stress–strain response of fiber-reinforced sand has been investigated using static and cyclic triaxial testing, as well as other combinations of fiber contents. Fiber-reinforced sand is tested for bulk modulus, shear modulus, and damping values. Effects of fiber contents on static and dynamic stress–strain response of fiber-reinforced soil are highlighted. It has been observed from results that, with an increase in fiber content modulus of elasticity, bulk modulus and shear modulus values increase while damping coefficients decrease for the same. It is believed that the highlighted numerical approach will be an alternative to laboratory experiments to determine the dynamic properties of fiber-reinforced soil. [ABSTRACT FROM AUTHOR]

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Tourism in Bali has surged post-COVID-19, with a 74.60% rise in arrivals from September 2022 to 2023, driving infrastructure development, notably in areas like Candidasa. However, safety concerns arise, especially in steep slope regions prone to landslides. This study employs cone penetration testing (CPT) data to assess its suitability for slope stability analysis amidst tourism development. By interpreting CPT data based on prior research, it shows obtaining ample soil parameters for such analysis is feasible. The research site, a Candidasa resort, exemplifies risks in hilly terrains. Fellenius-Morgenstern analysis reveals varying safety factors, indicating landslide susceptibility in certain scenarios. While CPT testing offers valuable insights, comprehensive geotechnical investigations are recommended for critical infrastructure projects to mitigate risks effectively. This study highlights the importance of comprehensive soil analysis and safety measures in the development of tourism infrastructure, especially in areas prone to geological hazards. [ABSTRACT FROM AUTHOR]

Improving soil strength and reducing the anticipated settlement and construction cost is a great paradox for civil as well as geotechnical engineers. In this paper, these aspects and other suitable types of ground improvement are discussed based on the principles of using geosynthetics for soil reinforcement. A series of load-settlement tests were also performed to compare strength and settlement of the silty sand reinforced with lime and one layer of geotextile. The study finds the maximum insertions of geotextile at 0.2D (3.0 cm) beneath the square footing base, and the lime percentage of 5.0% increases the UBC substantially. The UBC of lime-treated and geotextile-reinforced silty sand was to an optimum of 1,360 kN/m2 that has shown an enhancement of 258% compared to that of untreated and unreinforced silty sand that is approximately 380 kN/m2. Furthermore, comparative analysis between two ANN models was performed to provide improved estimate of the UBC, namely artificial neural network (ANN) and extreme learning machine (ELM). The developed computational models were then compared with experiment data, which proved that such models are more economical and effective than the expensive and time consuming conventional techniques. Consequently, based on the results, it was further validated that ELM possesses better generalization capability compared to ANN for predictive efficiency and thereby proves the efficiency of the model in estimating the ultimate bearing capacity of square footings incorporated with geotextile and lime-treated silty sand. This places the ELM model as a useful tool in the initial conceptual as well as the design for improvement steps of soil reinforcement. [ABSTRACT FROM AUTHOR]

History has shown that soil liquefaction could render buildings or infrastructures nonserviceable. It is understood that the soil liquefaction potential depends on the geotechnical engineering properties at the site and the regional seismicity in the surroundings, which are referred to as the geotechnical and geological factors in this paper. This research aims to explore their respective effect on soil liquefaction assessments. To investigate the effects, the (real) data from two cities in Taiwan were used as the problem sets, and the liquefaction factors of safety for the liquefiable soil at the sites were computed under different circumstances. The research found that regardless of the circumstances, the geological factor plays a predominant role over the geotechnical factor in soil liquefaction assessment. The sensitivity of the geological factor is over 95% quantified with the variance-based sensitivity analysis. Accordingly, one recommendation is that the practitioners should spend more effort characterizing the geological data in soil liquefaction assessment, which can obtain a more reliable outcome, which is the significance of this novel research. Practical Applications: The result of a soil liquefaction assessment depends on geological and geotechnical parameters. This research aims to quantify which is more predominant in soil liquefaction assessment. This transparent (sensitivity) study used the analytics called the variance-based sensitivity analysis. Using the accurate soil data in Taiwan and the geological models developed for the region, it was found that the geological factor is predominant in soil liquefaction assessment. Accordingly, when conducting a soil liquefaction assessment in the future, practitioners should spend more effort on characterizing the geological parameters, by which a more reliable outcome could be obtained. [ABSTRACT FROM AUTHOR]

Biogeotechnology has been widely applied to soil stabilization in the field of geotechnical engineering, compensating for the shortcomings of traditional geotechnical engineering materials. In this regard, the newly proposed bio-carbonation method of Reactive Magnesia Cement (RMC), based on Microbially Induced Carbonate Precipitation (MICP), has significant advantages in terms of energy conservation, carbon capture, and rapid soil solidification. However, this method lacks the combination of theory and practice. This paper presents a state-of-the-art review of the current research status of the bio-carbonation method in geotechnical engineering practice. Firstly, the paper systematically explains the concept and mechanism of the bio-carbonation method. Secondly, the paper summarizes various influencing factors affecting the bio-carbonation process and analyzes the engineering properties of bio-carbonated geo-materials. Finally, the paper concludes with the application scope of the bio-carbonation method in the geotechnical engineering field. It should be noted that the bio-carbonation method currently has some challenges, hence, further exploration of soil stabilization and crack repair is urgently needed in the future. [ABSTRACT FROM AUTHOR]

This study examined the geotechnical behavior of silty sand soil treated with cement and cement-mineral polymer through a series of static and dynamic tests. Uniaxial Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests were conducted on specimens with varying amounts of cement and polymer (i.e., 5, 7 and 9% by weight). Based on the results of UCS and ITS tests, the optimal combination of 7% cement and 7% cement-polymer was selected. Subsequently, California Bearing Ratio (CBR), Freezing and Thawing (F-T), and Large-scale cyclic triaxial (LCT) tests were performed on the optimal combinations. The results indicate that the treatment improves UCS, stiffness, CBR, and durability. By adding the polymer, the maximum UCS of the cement treated specimen can be achieved in a shorter curing period. Moreover, when exposed to F-T cycles, the cement-polymer specimen exhibited improvements in weight loss (about 0.6%) as well as compressive and tensile strength (about 200 kPa) compared to the cement treated specimen. In the dynamic tests, the cement-polymer specimen outperformed the cement specimen at low to medium cyclic deviatoric stress levels (up to 275 kPa). However, at higher stress levels, this trend was reversed. This behavior can be attributed to the formation of microcracks and cracks due to growth of needle-shaped microcrystals in cement-polymer specimen. Additionally, the cement-polymer treated specimen experienced lower permanent deformation during cycling loading. Overall, the polymer additive proves to be more effective in treating the base layer that withstands low and moderate stress levels, making it a suitable complement to a portion of cement. [ABSTRACT FROM AUTHOR]

Particle Flow Code, as noncontinuous media calculation software, has found extensive applications in geotechnical engineering research. To simulate real physical processes, the commonly utilized servo-computing methods involve adjusting the boundaries to modify the model's stress state. However, this approach alters the model's initial boundaries, thereby compromising computational accuracy. Addressing this issue, this paper introduces a particle self-regulation servo-computing method. This method controls the internal particle self-adjustment and completes the servo through error analysis. On the basis of the error analysis of the average stress within the particle system and the servo stress during the iterative process, the method automatically calculates the change in particle size within the system, achieving rapid convergence to servo stress tolerance after finite number of iterations. Validation through uniaxial compression tests and complex slope cases indicates that this particle self-regulation servo method yields an error of less than 5% compared with conventional rigid servo methods. That is, it accurately achieves numerical simulation state control without altering the outer contours of the boundary model. The proposed computational method is applicable to servo calculations for irregular models in two or three dimensions, providing a viable approach for stress control in models under complex conditions. [ABSTRACT FROM AUTHOR]

ABSTRACT The nonlocal general particle dynamics (NGPD) has been successfully developed to model crack propagation and large deformation problems. In this paper, the semi‐Lagrangian nonlocal general particle dynamics (SL‐NGPD) is proposed to solve brittle failure in rock slopes. In SL‐NGPD, the interaction between particles due to deformation is calculated in the initial configuration, while the friction contact interaction from discontinuities is calculated in the current configuration. The Van der Waals force model is utilized for friction contact. The bond‐level energy‐based failure criterion is developed to predict tensile/compressive‐shear mix‐mode cracks. The artificial viscosity and damage correction are used to enhance the numerical stability and accuracy when modeling brittle failure. The SL‐NGPD paradigm is numerically implemented through adaptive dynamic relaxation and predictor–corrector schemes for stable numerical solutions. The stability and accuracy of SL‐NGPD are verified by simulating compression tests. Thereafter, the crack coalescence patterns of double‐flaw specimens are investigated to understand the triggering failure mechanism of jointed rock slopes. Finally, the progressive failure process of the rock slope with step‐path joints is simulated to demonstrate its validity and robustness in modeling brittle failure in rockslides. The numerical results illustrate that the proposed SL‐NGPD is promising and performant for analyzing brittle failure problems in geotechnical engineering. [ABSTRACT FROM AUTHOR]

ABSTRACT The first‐order reliability method (FORM) is mostly employed in the existing geotechnical reliability‐based design (RBD) methods due to its computational simplicity and efficiency. However, the first‐order Taylor approximation of the limit state surface (LSS) may result in significant errors, especially in cases of highly nonlinear LSS characterized by substantial curvatures. Therefore, FORM‐based RBD methods require a modification of the curvatures to enhance the accuracy of the probabilistic constraints, specifically by converting the target reliability index into a more precise target failure probability. Correspondingly, reliability index‐based design is converted into failure probability‐based design. In this study, the parabolic second‐order reliability method (SORM), which avoids the Hessian calculations, is adopted to improve the accuracy of probabilistic constraints beyond what is achievable with FORM. The proposed SORM‐enhanced RBD method accounts for the curvature information of the nonlinear LSS, modifying the target reliability index to align with the exact target failure probability through the application of SORM. Moreover, by incorporating an implicit coupling function, multiobjective RBD can be effectively implemented without any additional surrogate model. Furthermore, the proposed RBD method is readily extended to reliability‐based design optimization (RBDO) through integration with an optimization strategy. The proposed RBDO method demonstrates a more precise convergence of the probabilistic constraints, surpassing the accuracy of FORM‐based RBDO methods. Notably, the proposed SORM‐enhanced RBDO method not only significantly improves accuracy but also bypasses the necessity for Hessian computation, which remains both the second‐order accuracy and first‐order efficiency. The feasibility of the proposed method is demonstrated through a mathematical example and three practical geotechnical design examples. [ABSTRACT FROM AUTHOR]

In the geotechnical engineering field, the rapid speed of urbanization triggers the need for direct measurements of sub-soil parameters through in situ testing, accompanied by instant results. At this juncture, the cone penetration test (CPT) is selected for this study. Here, an attempt is made to develop a correlation between cone penetration resistance (qc) and standard penetration blow count (SPT N) in order to predict a reference range of qc for cohesive (silty clay/clayey silt) sub-soil of different SPT-based consistencies. In this context, 25 CPT were conducted adjacent to conventional boreholes accompanied by SPT tests at eight important locations in West Bengal (WB) and Odisha (OR), India, focusing on infrastructure development. Primarily, sub-soil is characterized by bulk unit weight (γ) along with soil behavior type index (IC) estimated from the CPT and compared with the sub-soil profile identified from conventional boreholes. Further, a comparison of qc with SPT N is made to establish a correlation. Also, an attempt is made to tally the established correlation with the earlier correlations established for different regions. This study quantitatively establishes a quadratic correlation (R2 = 0.84) between qc and SPT N, which is found to be in good agreement with the previous correlations. Overall, the key findings of this study, i.e., the predicted range of qc, reveal a reliable method for assessing the consistency of cohesive sub-soil by virtue of the qc. However, this correlation is limited to soft to very stiff silty clay/clayey silt sub-soil formation. [ABSTRACT FROM AUTHOR]

The Unconfined Compressive Strength (UCS) measures a rock’s ability to withstand axial loads without lateral support, crucial for engineering applications. Accurate prediction of UCS is critical for the stability and safety of various civil engineering projects, such as foundation design, mining, and tunneling. The ability to predict UCS reliably ensures better project planning and execution, ultimately enhancing the safety and efficiency of engineering applications. The paper aims to develop an innovative method for predicting the $UCS$UCS of rocks using a combination of the Zebra Optimisation Algorithm (ZOA) and the Wild Geese Algorithm (WGA) integrated with the Least Square Support Vector Regression (LSSVR) predictive model. The novelty of the paper lies in the integration of ZOA and WGA optimizers with the LSSVR model to address the limitations of conventional methods, which often face challenges like slow achieving convergence and being stuck in local minima. The combination of these advanced algorithms results in significantly improved accuracy and convergence speed in UCS predictions, demonstrating a robust and reliable approach that advances the field of geotechnical engineering. The results show that combining ZOA and WGA optimizers with LSSVR enhances $UCS$UCS prediction accuracy and speed convergence. The LSZO models achieve a high level of precision, with a low RMSE value of 2.206 and an R2 value of 0.993. The safety and effectiveness of civil engineering projects are improved by this model, which provides a strong and trustworthy method for UCS prediction. [ABSTRACT FROM AUTHOR]

The problem of calculating the ultimate bearing capacity of a screw pile is studied using the limit equilibrium theory in this paper. Calculation methods for the critical screw pitch and the ultimate bearing capacity under two representative failure modes are proposed. Four key parameters affecting the ultimate bearing capacity are compared and analysed, and design optimisation suggestions are put forward. The results illustrate that the ultimate bearing capacity of the screw pile is mainly affected by the shear strength of the soil, the height of the screw thread and the screw pitch. When designing the screw pile, the height of the screw thread could be increased and the screw pitch reduced to some extent. [ABSTRACT FROM AUTHOR]

A constitutive model for the determination of anchor bearing capacity based on distributed sensing in geotechnical engineering From 2015 to 2017, as part of his work as head of research and development at Stump‐Franki Spezialtiefbau GmbH, the author devoted himself to the topic of pioneering measurement methods on the basis of Distributed Strain Sensing in geotechnics. One of the first developments was and is the monitoring of grouted bodies on strand grouted anchors. The new findings at that time were presented internationally at the DFI India, 2017 as well as nationally in construction technology, 2017 and locally at the 12th Hans Lorenz Symposium in Berlin, 2016. It was shown that the measurement results of the strain measurement using distributed strain sensing can be used to check over the following years whether the grouted anchors have been overloaded. The author already pointed out at the time that correct interpretation not only requires an understanding of the measuring process used, but also a certain wealth of experience in interpreting the measurement results in the direct context of geotechnics. As part of his work on the DIN standardization committee NA 005‐05‐17 AA Grouted anchors, accompanied by his practical experience, the author has dealt in depth with the question of what exactly is actually measured in the grout body using distributed strain sensing and what conclusions can be drawn about the load‐bearing capacity of grouted anchors on the basis of the measurement results. This article is intended to describe a constituent model on the basis of which further developments are possible for the interpretation of the measurement results with regard to their use as proof of economic efficiency and anchor load‐bearing capacity. [ABSTRACT FROM AUTHOR]

Predicting rock tunnel squeezing in underground projects is challenging due to its intricate and unpredictable nature. This study proposes an innovative approach to enhance the accuracy and reliability of tunnel squeezing prediction. The proposed method combines ensemble learning techniques with Q-learning and online Markov chain integration. A deep learning model is trained on a comprehensive database comprising tunnel parameters including diameter (D), burial depth (H), support stiffness (K), and tunneling quality index (Q). Multiple deep learning models are trained concurrently, leveraging ensemble learning to capture diverse patterns and improve prediction performance. Integration of the Q-learning-Online Markov Chain further refines predictions. The online Markov chain analyzes historical sequences of tunnel parameters and squeezing class transitions, establishing transition probabilities between different squeezing classes. The Q-learning algorithm optimizes decision-making by learning the optimal policy for transitioning between tunnel states. The proposed model is evaluated using a dataset from various tunnel construction projects, assessing performance through metrics like accuracy, precision, recall, and F1-score. Results demonstrate the efficiency of the ensemble deep learning model combined with Q-learning-Online Markov Chain in predicting surrounding rock tunnel squeezing. This approach offers insights into parameter interrelationships and dynamic squeezing characteristics, enabling proactive planning and support measures implementation to mitigate tunnel squeezing hazards and ensure underground structure safety. Experimental results show the model achieves a prediction accuracy of 98.11%, surpassing individual CNN and RNN models, with an AUC value of 0.98. [ABSTRACT FROM AUTHOR]

The design of pile foundations hinges significantly on the pile-bearing capacity (PBC), a crucial factor affected by numerous soil features and parameters. Piles serve as a key component in relocating structural loads to the ground, underscoring the need for accurately determining PBC in geotechnical design. While prior research has delved into utilizing artificial neural networks (ANN) for predicting PBC, they encounter shortcomings such as grappling with finding global minima and slow convergence rates. This study introduces Support Vector Regression (SVR) as a machine-learning approach, augmented by two meta-heuristic optimization techniques: the Giant Trevally Optimizer (GTO) and Smell Agent Optimization (SAO), to achieve optimal results. These techniques empower engineers and data scientists to develop more precise and reliable predictive models in geotechnical engineering, ultimately enhancing the safety and efficiency of foundation design and construction. Drawing upon an extensive dataset compiled from previous studies, a predictive model was constructed to estimate PBC using soft computing techniques. The outcomes overwhelmingly favored the SVGT model, a fusion of the SVR model with GTO, demonstrating excellent anticipative capacities with an outstanding R2 value of 0.998 and an impressively low RMSE value of 91.21. [ABSTRACT FROM AUTHOR]

Evaluating the bearing capacity of strip footing is a classic problem in geotechnical engineering, which has been investigated by many researchers. As the advancement of technology and urbanization, less and less land area can be available for the construction of facilities, which results in that many buildings must be constructed near slopes. The bearing capacity of strip footing constructed near slopes is usually lower than that on flat land. When the soil strength of slopes is not sufficient to support the external loads, it is often necessary to backfill or reinforces the slopes to make the strength of slope meet application requirements. The discontinuity layout optimization (DLO) method is therefore adopted in this paper to investigate the effects of various factors on bearing capacity and failure mechanism of strip footing on inclined multilayered natural slopes. Two conditions, normal slope and backfilled reinforced slope, are considered in the analysis. In addition, the influence of distance between the strip footing and slope, the number of soil layers, the thickness of the interlayer soil layer and earthquake on the unreinforced slope, and the influence of geosynthetic length and burial depth on the reinforced slopes are investigated. Eventually, the results showed that different factors have different impacts on the slope bearing capacity and failure mechanism. [ABSTRACT FROM AUTHOR]

Expansive clays with high plasticity need to be stabilized to prevent hazards that may arise due to the extreme volume changes experienced with moisture fluctuations. Utilizing a kind of natural and eco-friendly sustainable fiber named as basalt fiber into the soils has become a new issue that needs to be expanded in scope. In this paper, a high plastic soil was stabilized by these natural basalt fibers to reduce possible soil-induced disasters. Basalt fibers in different lengths were mixed into the clay at varied amounts. Due to the soil's sensitivity to water, the samples were prepared at distinct water contents, 2 on the dry and 3 on the wet side of the optimum. To question whether the strength loss due to the moisture change can be regained with basalt fibers or not, the strength tests were performed on both natural and stabilized samples. Through the tests, it was revealed that the strength of the expansive clays can be enhanced up to 280% at a fiber content of 2%. The highest strength was obtained at approximately 880 kPa by mixing 24 mm fibers with 15% water at 1 and 2% ratios. As anticipated, the long fibers (24 mm) supplied a real reinforcement even at high water contents. In addition, the obtained data set was used to train machine learning algorithms (linear, ridge, lasso, support vector, decision tree) that have just started to be applied in geotechnical engineering. Results have proved that, the decision tree regression outperformed the stress and strain with 0.85 R-squared (R2) in stress and 0.91 R2 in strain estimation. Additionally, it was revealed from the feature importance analyses that water content has an importance of approximately 85% on stress and up to 97% on strain. [ABSTRACT FROM AUTHOR]

This research evaluates the performance of two low- and high-plasticity clays as the sole precursors to develop alkaline activation at ambient temperature. NaOH solutions with different concentrations of 2 to 10 mol/L along with binary solutions with NaAlO2/NaOH mass ratios of 1 and 0.75 for CL and CH clays, respectively, have been used as alkaline activators. Unconfined compressive strength (UCS), indirect tensile strength (ITS), ultrasonic pulse velocity (UPV) and Atterberg limits tests have all been conducted to thoroughly assess the geotechnical properties of alkali-activated clays. The experimental results show that CL with the best performance when mixed with 8 M NaOH activator renders higher mechanical strength and stiffness compared to CH showing a peak at 4 M NaOH. This observation is primarily attributed to the higher amorphous content and a weak interlayer force in CL that in turn contributes to more reactive silicate phases and gel products. Moreover, binary solution considerably enhances the mechanical performance of parent clays by modifying the Si/Al ratio in the mixture. Another important observation is the vulnerability of the alkali-activated clays to cracks and expansion due to alkali–silica reactions, leading to a significant drop in their mechanical strength and stiffness. Microstructural analyses also reveal the increase in amorphous content and the formation of flocculated particles covered by aluminosilicate gels, especially in CL-based samples where the layer-like structure of clay changes to sponge-like with globular units. More importantly, uncalcined clay-based samples are observed to be prone to the curing time-dependent cracking associated with expanding phases due to alkali–silica reactions or flocculated particles. These observations could be useful in geotechnical engineering practice for a variety of field applications in terms of both safety and performance because not only natural clays have been used as the sole precursors but also a relatively low alkali concentration has contributed to the optimum improvement of the composite material. [ABSTRACT FROM AUTHOR]

Evaluation of the liquefaction susceptibility of soils is one of the most important subjects in geotechnical earthquake engineering. The energy-based liquefaction evaluation procedure, with a focus on seismic energy propagation and dissipation in soils, has attracted increasing attention in recent years. This paper presents a systematic analysis of cyclic triaxial test data of three series of silty sands through the energy-based approach. The stress-normalized accumulative dissipated strain energy per unit volume required for triggering liquefaction is used to evaluate the liquefaction potential of sands. It is a function of void ratio, fines content, and sand type. The pore pressure generation with the stress-normalized accumulative dissipated energy per unit volume can be simulated by a one-parameter pore pressure model, and the model parameter is affected by void ratio, fines content, and sand type. Unified characterizations of the stress-normalized accumulative dissipated energy per unit volume required for liquefaction and the fitting parameter of the pore pressure model are proposed in the framework of critical state soil mechanics. [ABSTRACT FROM AUTHOR]

Recent studies in earthquake engineering have outlined the difficulty of ground response analyses (GRAs) to replicate the observed ground motion and related variability at borehole array sites. Improvement of the seismic site response estimation requires accounting for and propagating the uncertainties in local soil conditions into surface ground motion. Uncertainties in site conditions arise from a number of factors, which include the uncertainties in the shear-wave velocity (VS) that are mainly caused by the natural spatial variability of soils and rocks. In this paper, a novel VS randomization approach is proposed to propagate the small-scale spatial VS heterogeneities into samples of VS profiles within a nonstationary probabilistic framework, to be further used in one-dimensional (1D) GRAs. The nonstationary approach is based on partitioning a borehole base-case VS profile into several locally stationary layers. The proposed approach was applied at three European sites exhibiting different subsurface soil conditions. Compared with both the classical stationary and an approach from the literature for VS randomization, the proposed approach provides a set of VS profiles fully consistent with the pseudoexperimental site signatures in terms of surface-wave dispersion curves, fundamental and higher-mode resonance frequencies, and site amplification. This paper also outlines the importance of the method used to measure VS profile in both the estimation of depth-dependent variability of VS at a given site and the prediction of site response variability. [ABSTRACT FROM AUTHOR]

Angle of repose is an important characteristic of lunar regolith, as it determines the slope stability of features such as hills and craters on the lunar surface and is useful for designing infrastructure and regolith conveyance and handling equipment. Using mineralogically accurate lunar regolith simulants LHS-1 and LHS-1D from Space Resource Technologies (SRT), the recent spin-off of the UCF Exolith Lab®, the relationship between angle of repose and aspects of the simulant, such as sample mass and particle size distribution, are explored. This study provides insight into what affects the angle of repose of lunar regolith, as well as how aspects of the regolith can be manipulated for in situ resource utilization and lunar construction applications. Through the manipulation of lunar regolith simulant particle size gradation and median particle diameter, it is possible to determine which aspects of particle size distribution most impact lunar regolith angle of repose. The results of this study indicate that while many characteristics of a regolith sample influence its angle of repose, the percentage of fines within a sample have the largest effect. [ABSTRACT FROM AUTHOR]

This study focuses on how soil's inherent variability, driven by environmental changes, introduces substantial uncertainty into geotechnical considerations. Voids forming underground are a key source of this uncertainty, affecting subsoil structures like piles. Using a two-dimensional discrete-element method and considering both fundamental (micro) and engineering (macro) approaches, this study investigates the influence of voids in sandy soil on a pile's behavior, especially on the pile's bearing capacity and lateral pressure coefficient acting upon its shaft. The results reveal a critical zone around the pile where voids can dramatically reduce the pile's bearing capacity, with load reductions of up to 63% in the most extreme cases. Surprisingly, voids have a minimal impact on the lateral pressure coefficient along the pile wall. Thus, it is deduced that the primary cause of the pile's load reduction in the presence of the void is the decreased resistance at the pile's tip. In summary, this research underscores how voids in sandy soil significantly affect the bearing capacity of piles, emphasizing the importance of understanding these effects for safe and efficient subsoil structure design in geotechnical engineering. [ABSTRACT FROM AUTHOR]

Accurate prediction of soil liquefaction is important for preventing geological disasters. Soil liquefaction prediction models based on machine learning algorithms are efficient and accurate; however, some models fail to achieve highly precise soil liquefaction predictions in certain areas because of poor generalizability, which limits their applicability. Thus, a soil liquefaction prediction model was constructed using the CatBoost (CB) algorithm to support categorical features. The model was trained using standard liquefaction datasets from domestic and foreign sources and was optimized with Optuna hyperparameters. Additionally, the model was evaluated using five evaluation metrics and its performance was compared to that of other models that use multi-layer perceptron, support vector machine, random forest, and XGBoost algorithms. Finally, the prediction capability of the model was verified using three case studies. Experimental results demonstrated that the CB-based model generated more accurate soil liquefaction predictions than other comparison models and maintained their performance. Hence, the proposed model accurately predicts soil liquefaction and offers strong generalizability, demonstrating the potential to contribute toward the prevention and control of soil liquefaction in engineering projects, and toward ensuring the safety and stability of structures built on or near liquefiable soils. [ABSTRACT FROM AUTHOR]

Basalt is an important geotechnical material for engineering construction in Southwest China. However, it has complicated structural features due to its special origin, particularly the widespread occurrence of hidden cracks. Such discontinuities significantly affect the mechanical properties and engineering stability of basalt, and related research is lacking and unsystematic. In this work, taking the underground caverns in the Baihetan Hydropower Station as the engineering background, the size-dependent mechanical behaviors and excavation responses of basalt with hidden cracks were systematically explored based on a synthetic rock mass (SRM) model combining the finite-discrete element method (FDEM) and discrete fracture network (DFN) method. The results showed that: (1) The DFN–FDEM model generated based on the statistical characteristics of the geometric parameters of hidden cracks can consider the real structural characteristics of basalt, whereby the mechanical behaviors found in laboratory tests and at the engineering site could be exactly reproduced. (2) The representative elementary volume (REV) size of basalt blocks containing hidden cracks was 0.5 m, and the mechanical properties obtained at this size were considered equivalent continuum properties. With an increase in the sample dimensions, the mechanical properties reflected in the stress–strain curves changed from elastic–brittle to elastic–plastic or ductile, the strength failure criterion changed from linear to nonlinear, and the failure modes changed from fragmentation failure to local structure-controlled failure and then to splitting failure. (3) The surrounding rock mass near the excavation face of underground caverns typically showed a spalling failure mode, mainly affected by the complex structural characteristics and high in situ stresses, i.e., a tensile fracture mechanism characterized by stress–structure coupling. The research findings not only shed new light on the failure mechanisms and size-dependent mechanical behaviors of hard brittle rocks represented by basalt but also further enrich the basic theory and technical methods for multi-scale analyses in geotechnical engineering, which could provide a reference for the design optimization, construction scheme formulation, and disaster prevention of deep engineering projects. [ABSTRACT FROM AUTHOR]

Microbially induced calcium carbonate precipitation (MICP) is a technique used in geotechnical engineering to reinforce soil and rock. While it is commonly used for soil reinforcement, its application for rock reinforcement in saline–alkaline environments is limited. In order to improve the reinforcement effect of microbially induced calcium carbonate on rock joints in saline–alkaline environments, experiments were conducted to cultivate Sporosarcina pasteurii. The strengthening effects of MICP on rock joints were evaluated using the direct shear test. Samples of sandstone with rough surfaces were reinforced by MICP. The shear strength characteristics of rock joints reinforced by CaCO3 were then assessed. The results showed that after being domesticated in a saline–alkaline environment, the bacterial concentration reached over 96% of that in a neutral environment. The domesticated Sporosarcina pasteurii performed well at temperatures between 10~30 °C in saline–alkaline conditions. In the saline–alkaline environment, the shear strength of rock joints and the production rate of CaCO3 were higher, and the Sporosarcina pasteurii with domestication showed better joint repair performance. The peak shear strength of rock joints reinforced by MICP increased with curing time, with a quicker strength development in the early stage and a slower increase later on. The peak shear strength of cemented rock joints significantly surpassed that of uncemented rock joints. This research can provide valuable insights for the application of MICP technology in reinforcing rock joints in saline–alkaline environment. [ABSTRACT FROM AUTHOR]

The materials involved in geotechnical engineering are objects of concern in granular mechanics. In order to study the influence of the sliding friction coefficient corresponding to different-sized elements in the discrete element method (DEM) on the simulation results, we establish a two-dimensional DEM model based on the experimental method to analyze a slope example. The correctness of the DEM model is verified by comparing the sliding surface of a finite element method (FEM) model and the DEM slope model. A sliding friction coefficient algorithm based on the experimental method is embedded into the DEM slope model and compared with the original model. The comparison results show that embedding the DEM model into the sliding friction coefficient algorithm leads to an increase in displacement. The reason for this is that the contact information between elements of different sizes has changed, but the displacement trend is the same. Different sliding friction coefficients should be set based on different-sized elements in the DEM, as they can improve simulation accuracy. [ABSTRACT FROM AUTHOR]

The earth pressure of slope retaining structure is one of the problems that are often encountered in geotechnical engineering but have not yet been fully understood and well solved. At present, there are still a lot of problems that need to be solved. For complex conditions such as stratified soil or containing ground water, the distribution law of earth pressure and the displacement mode of retaining structure need to be further studied. This paper summarizes the existing research on earth pressure of slope retain structures. According to the research methods, it is divided into three categories: research on the theoretical calculation method of earth pressure, research on earth pressure by model test, and research on earth pressure by numerical simulation. Focused discussions are carried out respectively, and the previous research results are summarized. At present, there are still a lot of problems that need to be solved in the research of earth pressure of slope retaining structure, and the calculation formula of earth pressure and the assumed fracture surface of earth are lack of experimental verification and engineering measurement. [ABSTRACT FROM AUTHOR]

In this study, the mechanical behavior of novel fully grouted cable rock bolts made of basalt fiber–reinforced polymer (BFRP) was investigated, which included pullout and double-shear joint behavior. Three BFRP cables were prepared: (1) single-tendon; (2) untwisted multiple-tendon; and (3) twisted multiple-tendon. In the pullout tests, the effects of cable type, borehole diameter, and encapsulated length were studied. However, the influence of the pretension load level was focused on in the double-shear joint tests. The results suggested that an overly thick grout annulus significantly reduced the pullout strength and stiffness. For the BFRP cable with multiple tendons, the initial pullout stiffness was enhanced compared with the BFRP cable with a single tendon due to better interfacial bonding with the grout. In the double-shear joint tests, the pretension of the cable significantly improved the shear capacity and stiffness. With an enhancement in the confinement from pretension, the partial failure of the grout at an early stage could be prevented. The parallel and twisted-tendon BFRP cable rock bolts had larger failure displacements than the single-tendon cable. This analytical study found that a pullout analytical model available in the literature was accurate when back-calculating the stress conditions along the rock bolt. The predicted shear capacity of the rock joint showed good agreement with the experimental values. A parametric study indicated that the joint shear capacity was sensitive to the tensile and shear strengths of the cable but was irrelevant to the cable moduli. Considering the effectiveness of pretension and creep safety for BFRP, a suitable range for the pretension load was suggested. Practical Applications: This study attempts to promote the use of novel, fully grouted cable rock bolts made of basalt fiber–reinforced polymer (BFRP) materials in geotechnical engineering applications. Different types of cable rock bolts are produced, which include single-tendon, untwisted multiple-tendon, and twisted multiple-tendon cables. In the pullout tests, the untwisted multiple-tendon cable exhibited the highest pullout capacity, because of its better interfacial bonding with the grout. From the double-shear joint tests, the pretension of the cable could significantly improve the shear capacity and stiffness. In general, the BFRP cable rock bolts could have a competitive mechanical behavior compared with the steel rock bolts. The respective analytical models for pullout and double-shear joint specimens have proved to be accurate for predicting the mechanical responses of the cable rock bolts. These concise but reliable analytical models could allow researchers and designers to better utilize these novel cable rock bolts in potential applications. [ABSTRACT FROM AUTHOR]

The stability of underground diaphragm walls is crucial for ensuring the safety and integrity of trench excavations in geotechnical engineering. This study addresses this critical issue by proposing a novel destabilization mechanism based on a sliding body model specifically designed for diaphragm wall trenching operations. The research employs an analytical framework rooted in soil mechanics and plasticity theory, utilizing limit equilibrium analysis to develop a method for calculating the minimum required slurry density and corresponding safety factor for trench stability. The study compares two distinct approaches to slurry density computation, analyzing their sensitivity to various influencing factors. Theoretical findings are validated through multiple real-world engineering case studies. Comparative analysis demonstrates the superiority of the proposed method, particularly in assessing trench stability within clay layers. Key variables influencing the safety factor are identified, including trench length, slurry density, soil friction angle, and the relative height difference between slurry and groundwater levels. Results indicate that actual slurry densities observed in practice consistently fall within the bounds predicted by the theoretical calculations. This research contributes a valuable theoretical framework to the field of diaphragm wall construction, offering improved accuracy in stability assessments and potentially enhancing safety in geotechnical engineering projects. [ABSTRACT FROM AUTHOR]

Underground geotechnical engineering encounters persistent challenges in ensuring the stability and safety of surrounding rock structures, particularly within rocky tunnels. Rock reinforcement techniques, including the use of steel mesh, are critical to achieving this goal. However, there exists a knowledge gap regarding the comprehensive understanding of the mechanical behavior and failure mechanisms exhibited by steel mesh under diverse loading conditions. This study thoroughly explored the steel mesh's performance throughout the entire loading-failure process, innovating with detailed analysis and modeling techniques. By integrating advanced numerical modeling with laboratory experiments, the study examines the influence of varying reinforcement levels and geometric parameters on the steel mesh strength and deformation characteristics. Sensitivity analysis, employing gray correlation theory, identifies the key factors affecting the mesh performance, while a BP (Backpropagation) neural network model predicts maximum vertical deformation with high accuracy. The findings underscore the critical role of steel diameter and mesh spacing in optimizing peak load capacity, displacement, and energy absorption, offering practical guidelines for design improvements. The use of a Bayesian Regularization (BR) algorithm further enhances the predictive accuracy compared to traditional methods. This research provides new insights into optimizing steel mesh design for underground applications, offering an innovative approach to enhancing structural safety in geotechnical projects. [ABSTRACT FROM AUTHOR]

Geotextiles are widely used as reinforcing elements in many geotechnical engineering applications such as mechanically stabilized earth walls, reinforced soil slopes, capping of high-water content clays in landfills, reinforced embankments for railways and roadways, and so on. The ultimate strength of geotextile is obtained from the load-displacement plot; however, the failure mechanism evaluation of local displacement is crucial to understand the serviceability state. In the present study, the image-based deformation measurement technique is used to evaluate the local displacement within geotextile at different locations during the wide-width tensile test. Further, the load-displacement plots are obtained for different geotextiles and a comparison is made between the measured displacements from the instruments and through an image-based deformation measurement technique. Additionally, the strength of geotextiles with imbibed defects at different orientations and corresponding failure patterns is investigated. The imbibed defect in geotextile is in the form of slits having orientations varied as vertical, horizontal, and inclined with respect to the loading direction. It has been observed that geotextile with vertical slit has the highest strength, followed by geotextile with inclined and horizontal slits. The present study results provide insight into the variation in the strength and displacement field of geotextiles having defects. [ABSTRACT FROM AUTHOR]