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It is well known that the roughness of a wall plays a crucial role in determining the passive earth pressure that is exerted on a rigid wall. While the effects of positive wall roughness have been extensively studied in the past few decades, the study of passive earth pressure with negative wall friction is rarely found in the literature. This study aims to provide a precise solution for negative friction walls under passive wall conditions. The research is initiated by adopting a radial stress field for the cohesionless backfill and employs the concept of stress self-similarity. The problem is then formulated in a way that a statically admissible stress field be developed throughout an analyzed domain using a two-step numerical framework. The framework involves the successful execution of numerical integration, which leads to the exploration of the statically admissible stress field in cohesionless backfills under negative wall friction. This, in turn, helps to shed light on the mechanism of load transfer in such situations so that reliable design charts and tables be provided for practical uses. The study continues with a soft computing model that leads to more robust and effective designs for earth-retaining structures under various negative wall frictions and sloping backfills. [ABSTRACT FROM AUTHOR]

The excavation of Earth Pressure Balance (EPB) shield can be divided into two distinct stages, i.e. advancing and lining installation. The frictional force applied on surrounding soils reverses at these two stages, which is harmful to the settlement control. Based on Mindlin's method, a new model of surface settlement is derived to involve the reversed friction. A closed form formula is then obtained for the major type of metro tunnels. Main operational parameters are also used as input of the formula. Numerous operational data and measured settlements are collected from EPB tunnels of Chengdu Metro, Line 7. The proposed formula is validated against these field data in sandy gravels. It is shown that the new formula gives reasonable prediction of surface settlement along the tunnel sections. The accuracy of new formula is significantly higher than that of Peck's formula. This study provides a new vision in settlement control of EPB shield tunneling. The increase of chamber pressure will induce higher negative friction during the lining installation. Therefore, surface settlement of EPB tunneling cannot be controlled by just increasing chamber pressure. A balanced relationship between the chamber pressure and the thrust should be maintained instead. [ABSTRACT FROM AUTHOR]

The stability of side walls in terraced fields constructed within expansive soil regions represents a critical challenge, often leading to structural failure due to the unique wetting–swelling behavior of the soil. This study employs a comprehensive approach, integrating analytical and numerical methods to elucidate the mechanism of overturning failure attributed to the swelling effect of expansive soil under conditions of layer‐by‐layer saturation. Initially, the earth pressure acting on side walls, constructed from fiber ecological bags, is assessed in their natural, unsaturated state using Bishop's formula for unsaturated shear strength. The study further explores the failure mode through one‐dimensional analytical analysis, focusing on the horizontal and unrestrained expansion of expansive soil during progressive saturation. Subsequently, the deformation of the side wall and the swelling effect of the soil are numerically evaluated. This is achieved by analogizing the wetting–swelling deformation field in expansive soil to an equivalent temperature field, thereby facilitating the use of finite element numerical simulation to investigate the overturning failure mechanism. Findings indicate that in the natural unsaturated state, the side walls remain stable under no earth pressure. However, as saturation depth attains a critical depth of 1.4 m during layer‐by‐layer saturation, the upper wall rotates outward in the form of local overturning failure, and the corresponding infiltration saturation depth is the critical depth for the local instability of the side wall. The investigation identifies the wetting–swelling effect as the predominant factor leading to the structural failure of side walls in terraced fields situated in expansive soil areas. Moreover, a critical infiltration saturation depth of 2.6 m is determined, beyond which the stability of the side walls is compromised. This research contributes significantly to the understanding of the failure mechanisms affecting terraced agricultural infrastructures in expansive soil regions, offering a theoretical foundation for the development of more resilient construction strategies. [ABSTRACT FROM AUTHOR]

Ground fissures, as a typical geohazard, pose potential georisks to the construction and maintenance of urban transportation infrastructure. Under the influence of ground fissures, the segmented tunnel structure used in subway systems complicates the propagation of subway train vibrations. In this study, the soil acceleration, earth pressure and contact pressure of a three-section subway tunnel under dynamic loading of a subway train in a ground fissure environment were observed and analyzed by physical modeling tests, and the effects of the presence and activity of the ground fissure and tunnel segmentation were discussed. The results show that the vibration generated by the subway traveling will have different degrees of attenuation when propagating in all directions in the soil layer, and the ground fissure has a damping effect on the subway vibration. The attenuation and enhancement of acceleration by ground fissure is affected by the activity and propagation direction of ground fissure. The distribution of additional earth pressure is affected by the ground fissure, soil contact state, which is related to the ground fissure activity state. The ground fissure activity on the contact additional pressure mainly focuses on the bottom and top of the tunnel and there are differences in the location of the hanging wall and footwall. Three-section tunnels have a stronger vibration response and vibration attenuation than monolithic tunnels due to the influence of segmentation. Based on the consideration of the effects of ground fissure and tunnel segmentation, the tunnel design mainly takes into account the amount of ground fissure activity and determines the structural measures, the tunnel structure at the location of the ground fissure is strengthened, in addition to the vibration attenuation measures for the segmented tunnels when crossing the ground fissure. The discussion of mechanical response and design measures in this study helps to reduce the georisk of ground fissures on urban underground transportation infrastructure. [ABSTRACT FROM AUTHOR]

Pile-supported embankments have been recognized as long-standing solutions for construction in compressible soft soils. Instead of improving the physical and mechanical properties of the soft soil, this method emphasizes efforts to transfer the embankment load to a competent layer below the compressible layer. Mortar column inclusion (inklusi kolom mortar or IKM) is recognized as one of the rigid inclusions in a pile-supported embankment. The IKM combined with a load transfer platform (LTP) has been widely utilized to support embankments. Studies on pile-supported embankments have generally focused on the arching mechanisms and geotextile tensile force evaluations; however, most of these investigations were conducted on soft cohesive soils. The application of pile-supported embankment on peat has rarely been studied comprehensively. This study presents a full-scale trial embankment on peat in West Sumatra, Indonesia. The 8-m-high trial embankment was supported by a series of IKM piles and a geotextile-reinforced LTP layer; instruments were then installed in the embankment, ground, LTP, geotextile, and IKM. These instruments included a series of vibrating wire earth pressure cells, vibrating wire strain gages, fiber optic sensors, vibrating wire piezometers, settlement profilers, settlement plates, and inclinometers. The instruments provided observations on the ground movements, IKM displacements, and stresses in the materials. Comprehensive evaluations from field monitoring allowed study of load transfer via the arching mechanism, deformation pattern, and IKM performance in peat. Finite element analyses (FEAs) were also conducted for comparison and verification. The field monitoring results and FEAs showed good agreement, thereby demonstrating the potential of the proposed ground improvement method for embankment construction on peat. [ABSTRACT FROM AUTHOR]

Effective soil conditioning is critical for mechanized shield tunneling, yet the selection of conditioning parameters remains experience‐oriented. This study presents a machine learning–informed soil conditioning strategy, aiming at enabling automatic decision‐making for soil conditioning during tunneling. The proposed procedure includes feature engineering to process raw data, the selection of an optimal model, and a committee‐based uncertainty quantification strategy to evaluate the reliability of models. High‐dimensional data visualization techniques are leveraged to examine the influence of data distribution on the model's performance. Results demonstrate that feature engineering and the selection of models lay a foundation for machine learning–enabled automatic soil conditioning, while historical soil conditioning parameters should be incorporated in models to account for time‐dependent features during tunneling. The committee‐based uncertainty quantification strategy can effectively identify the reliability of both interpolated and extrapolated predictions. The proposed data‐driven soil conditioning framework can promote the application of machine learning toward automating earth pressure balance (EPB) shield tunneling. [ABSTRACT FROM AUTHOR]

Excavation-induced soil arching is a key factor influencing the responses of the ground and underlying structures. This soil arching below an excavation base is defined as downward soil arching in comparison with that above a trapdoor or tunnel, featured with the downward developing direction. To recognize and assess the downward soil arching, two centrifuge tests in the plane-strain condition were conducted in the dense and loose sand. Variations of Earth pressure, basal heave, and shear wave velocity below the excavation base were observed, and the influence of the relative density was also investigated. The test results indicated the existence of differential deformation and stress transfer below the excavation base, and the downward soil arching is confirmed. The contributions of the downward soil arching to the restriction of the excavation-induced stress release and the ground response were found. Further, the boundary of the loosened zone and the width of the arch foot were determined in the dense and loose sand, respectively. In addition, the arched-type basal heave and stress-related shear wave velocity were observed. The significant ground heave and reduction of the shear wave velocity were found within the loosened zone. [ABSTRACT FROM AUTHOR]

A novel finite-element (FE) procedure for analyzing slope stability was recently developed and encoded into a Fortran computer code S4DINA 2.0. This innovative approach involves a gradual increment in the principal stress deviator in a specific way until an unstable condition is reached. In the original version of S4DINA 2.0, the initial stress field was assessed using the gravity loading procedure (GLP), which has various limitations. This paper introduces the fictitious excavation method (FEP) as an alternative procedure for estimating initial stresses. After incorporating the FEP into S4DINA 2.0, a parametric investigation was conducted to explore the effect of the coefficient of soil pressure at rest (K0) and Poisson's ratio (ν) on the GLP and FEP, which used three selected slope examples. The evolution of the factor of safety (FOS), as determined by the stress deviator increasing model (SDIM), was examined for ν for a variety of soil friction angles (ϕ′). The findings of this paper were documented in detail. The inclusion of K0 as an inherent soil property in the GLP was unfeasible due to the formulation nature of the GLP. In addition, when this method is used, the resulting FOS might significantly deviate from the accurate result in numerous instances. However, in scenarios where K0 exceeds one, the FEP remains the exclusive solution, and when K0 is less than one, selecting the FEP with an appropriate ϕ′ value is the best choice for achieving a rigorous FOS. [ABSTRACT FROM AUTHOR]

Most of the previous studies on the behavior of cemented sand were carried out under axisymmetric conditions. In this study, the failure and stress–strain behavior of cemented sand under plane strain conditions were investigated by drained plane strain tests. It was found that the behavior of cemented sand was much affected by its consolidation history, as the bonding began to break when the consolidated stress was larger than the yielding stress during coefficient of lateral earth pressure at rest (K0) consolidation. The growth of the intermediate principal effective stress (σ2′) made the stress–strain curve stiffer and less dilative under plane strain than under axisymmetric conditions. The bonding mobilization during the test was analyzed using an energy-balance approach. The friction between the sand particles and the breaking of the cementation bonding was assumed to dissipate the work done on the cemented sand. The peak friction angle of the cemented sand was not influenced by the cement content (cc), while the effective cohesion increased with the amount of cementation, as indicated by the cc in a power function relationship. In comparison to axisymmetric conditions, plane strain conditions result in a higher friction angle and lower cohesive strength. [ABSTRACT FROM AUTHOR]

Soil conditioning is essential for addressing the stratum applicability problem of earth pressure balance (EPB) shields. Under high water pressures, EPB shields spew water and soil when excavating coarse-grained strata. Typically, foam combined with polymers and slurry is used to solve spewing. However, in current techniques, slurry, foam, and the other agents are mixed with soil separately, their synergistic effect is seldom realized. In this study, an anionic surfactant was used to foam in bentonite slurry to form bubble–slurry to maximize the synergy between bubbles and slurry. The slump, volume stability, and permeability test of bubble–slurry-conditioned sand was conducted to examine the conditioning effect, and the stratum applicability of bubble–slurry was determined from the perspective of permeability. It was found that the conditioning effect of bubble–slurry in coarse gravel soil was excellent and could expand the applicability of EPB shields. The main stabilization mechanism of bubble–slurry is that bentonite particles provide a space barrier for bubbles. And three seepage modes of bubble–slurry-conditioned sand were innovatively defined, and the occurrence conditions of the three seepage modes were analyzed according to the permeability coefficient of sand, initial dynamic shear force of bubble–slurry, and hydraulic gradient. [ABSTRACT FROM AUTHOR]

In recent years, foundation pit construction has been rapidly developing in the direction of deep and large-scale, leading to the frequent occurrence of construction accidents. The pit construction process is characterised by a complex environment, high construction risk, and numerous coupling effects between the construction risk factors. In this paper, 23 main accident-causing factors in foundation pit construction are determined based on the six major risk accident types. In addition, the Grey-DEMATEL-Fuzzy comprehensive evaluation method of the risk evaluation model is introduced for better prediction and judgment of risk level, which combines the grey system theory with the method of decision-making experimental analysis, and in the case of inaccurate or incomplete information, the use of less data can achieve the evaluation results with a high degree of reliability, and it will effectively avoid the impact of the lack of information as well as the subjectivity in the process of risk evaluation. Through the Grey-DEMATEL method, the central degree value for each risk indicator factor is calculated, the coupling role and importance of each risk indicator are analysed, and the indicator weights are calculated. Based on the calculated weights, the fuzzy comprehensive evaluation method is used to evaluate the overall risk level. The empirical research on the deep foundation pit construction project of Haitangxi subway station in Chongqing reveals that the excessive lateral earth pressure on the pile wall is the most prominent risk factor. The overall risk level of the construction process is medium, and the risk is within the controllable range. On this basis, corresponding preventive measures can be formulated, providing a basis for risk prevention in the construction of deep foundation pit projects. [ABSTRACT FROM AUTHOR]

In China, several expressways have been designed as prefabricated box culverts with hinge connections, which have different structural features from the prefabricated culverts in other countries. The difference would contribute to the culvert–soil interaction of prefabricated box culverts, which could affect the earth pressure on the culvert. Based on the field test and numerical simulation method, a hinged prefabricated box culvert (HPBC) with a span of 4 m and a rise of 4 m was investigated, which was applied to the Xi-Yu expressway in China. The objective of this research was to investigate the vertical earth pressure on the top slab of the HPBC culvert at different backfill heights through the field tests. The FLAC3D software was employed to conduct further analysis of the effects of backfill height, backfill modulus, and foundation modulus on the vertical earth pressure on the top slab of HPBC. The differences between the HPBC and monolithic box culvert (MBC) were also examined. Furthermore, a revised method for calculating the vertical earth pressure on the top slab was put proposed and compared with the AASHTO method for calculating earth pressure on the top of culverts and the values taken from the Chinese culvert design code. The proposed method is capable of improving the accuracy of the earth pressure approach, making it more representative of actual conditions. Subsequently, the sensitivity analysis of backfill height, backfill modulus and foundation modulus to the vertical earth pressure concentration coefficient of the top slab was carried out by using the principle of orthogonal array analysis and the modified calculation method proposed in this paper. The findings of this study offer valuable insights into the determination of culvert top earth pressure of HPBC. [ABSTRACT FROM AUTHOR]

The design of segmental geosynthetic mechanically stabilized walls with masonry block facing is often governed by the loads that develop at the connection between the facing and geosynthetic. Yet the current understanding of the mechanisms involved in the mobilization of such connection loads is, at best, incomplete. The testing apparatus developed as part of this study facilitates simulating the transference of stresses at the face and evaluating the facing connection loads in geosynthetic-reinforced soil walls. This study assesses the connection loads between a geogrid reinforcement connected frictionally to modular concrete blocks. A comprehensive instrumentation program was implemented to capture lateral earth pressures, geosynthetic strains and loads acting at the geogrid-block connection in a geosynthetic-reinforced unit cell subjected to incremental surcharge stages. Results indicate that conventional calculations, based on earth pressure theory, may underestimate the facing connection loads, mainly when the connection loads are triggered by the differential settlement of the backfill relative to the block facing. When this mechanism dominates the mobilization at the connection, reinforcement loads increase as the differential settlement increases, developing down-drag forces at the connection between the geogrid and modular blocks. • Facing connection loads should not be understood only as a result of earth pressures. • Relative settlements between block facing wall and backfill soil cause a down-drag deformation of the reinforcement. • Down-drag deformation of the reinforcement induces significant connection loads. • The magnitude of connection loads increases with the magnitude of down-drag deformation. • Facing connection loads can be greater than the maximum reinforcement tensile load. [ABSTRACT FROM AUTHOR]

The wave reflection and transmission (R/T) coefficients in fluid-saturated porous media with the effect of effective pressure are rarely studied, despite the ubiquitous presence of in situ pressure in the subsurface Earth. To fill this knowledge gap, we derive exact R/T coefficient equations for a plane wave incident obliquely at the interface between the dissimilar pressured fluid-saturated porous half-spaces described by the theory of poro-acoustoelasticity (PAE). The central result of the classic PAE theory is first reviewed, and then a dual-porosity model is employed to generalize this theory by incorporating the impact of nonlinear crack deformation. The new velocity equations of generalized PAE theory can describe the nonlinear pressure dependence of fast P-, S- and slow P-wave velocities and have a reasonable agreement with the laboratory measurements. The general boundary conditions associated with membrane stiffness are used to yield the exact pressure-dependent wave R/T coefficient equations. We then model the impacts of effective pressure on the angle and frequency dependence of wave R/T coefficients and synthetic seismic responses in detail and compare our equations to the previously reported equations in zero-pressure case. It is inferred that the existing R/T coefficient equations for porous media may be misleading, since they lack consideration for inevitable in situ pressure effects. Modeling results also indicate that effective pressure and membrane stiffness significantly affect the amplitude variation with offset characteristics of reflected seismic signatures, which emphasizes the significance of considering the effects of both in practical applications related to the observed seismic data. By comparing the modeled R/T coefficients to the results computed with laboratory measured velocities, we preliminarily confirm the validity of our equations. Our equations and results are relevant to hydrocarbon exploration, in situ pressure detection and geofluid discrimination in high-pressure fields. [ABSTRACT FROM AUTHOR]

Weathered rock (especially granite) slopes are prone to failure under the action of rainfall, making it necessary to study the response of weathered rock slope to rainfall infiltration for landslide prevention. In this study, a series of model tests of weathered rock slope under different conditions were conducted. The matric suction, volumetric water content, earth pressure and deformation of slope were monitored in real time during rainfall. The response of the slope to rainfall infiltration, failure process and failure mode of slope under different conditions were analyzed, and the early warning criterion for the failure of weathered rock slope caused by rainfall was studied. The results show that the slope deformation evolution process under rainfall condition was closely related to the dissipation of matric suction. When the distribution of the matrix suction (or water content) of slope met the condition that the resistance to sliding of the slip-mass was overcome, the displacement increased sharply and landslide occurred. Three factors including rainfall process, lithologic condition and excavation condition significantly affect the response of weathered rock slope to rainfall. It can be found from the test results under different conditions that compared with intermittent rainfall condition, the rainfall intensity and infiltration depth were smaller when the slope entering accelerated deformation stage under the condition of incremental rainfall. The accumulated rainfall when weathered clastic landslide occurring was greater than that of weathered granite, which results in greater disaster risk. The excavation angle and moisture distribution of a slope were the main factors affecting the stability of a slope. In addition, the evolution processes and critical displacement velocities of slopes were studied by combining the deformation curves and matrix suction curves, which can be used as reference for early warning of rainfall-induced weathered rock landslide. [ABSTRACT FROM AUTHOR]

The problem considered in this paper is the passive earth pressure determination under various rigid wall geometry with negative wall-soil friction. An exact solution based on statically admissible stress fields is employed to evaluate the impact of negative wall-soil friction and inclined walls on the design of retaining walls. A series of conservative solutions for the passive earth pressure coefficient in the presence of negative wall friction is obtained, shedding light on the load transfer mechanism of cohesionless backfill materials. While focusing on the passive earth pressure coefficient, the study further identifies the stress state transition zone in the backfill and the influence of wall inclination on passive earth pressure. In addition, the load transfer mechanism of cohesionless backfill material in a retaining wall is affected by various factors, including wall geometry, degree of negative wall friction, the direction of the major principal stress at the wall, and the position and orientation of the transition zone and line of stress discontinuity. It follows that comprehensive design charts involving various rigid wall geometry and negative wall-soil friction are provided for engineering practice. Overall, the study successfully characterizes the admissible stress field in the backfill of rigid retaining walls, contributing to the knowledge of retaining wall design under the effect of negative wall friction. [ABSTRACT FROM AUTHOR]

For the excavation of a shallow tunnel in soft soil, the controllable range of the support pressure is narrow due to the small area of overburdened earth pressure, and passive failure of the tunnel face can be easily induced; therefore, the soft soil must be reinforced to increase the stability of the tunnel face. In this work, numerical simulation and theoretical analysis were adopted to explore the passive failure mechanism of a tunnel face in soft ground reinforced with a soil–cement wall. First, finite element analyses were conducted to investigate the passive failure mechanism. The impact of L1 (the distance between the tunnel face and soil–cement wall) on the passive failure mode was disclosed. Three types of failure modes—the full-penetration, partial-penetration, and non-penetration modes—were identified based on the shear failure zone and variation in Pp (the limit support pressure of passive failure) with L1. Then, analytical models based on the limit equilibrium method for the three passive failure modes were established, and formulas for predicting Pp were derived. The predictions by the formulas were validated by the numerical results, and their differences were within 10%. Both indicate that Pp achieved a maximum value when L1 = 0.2D (D is the diameter of tunnel); therefore, it is reasonable to choose a distance of 0.2D between cement walls in this engineering project. [ABSTRACT FROM AUTHOR]

This paper proposes a calculation method of displacement-dependent three-dimensional (3D) earth pressure on flexible walls of the foundation pits, further considering spatial effects, layered cohesive soil, and seepage effect on earth pressure. Based on improved Coulomb's earth pressure theory, the displacement-dependent 2D earth pressure model for flexible walls is established. By introducing the concepts of spatial influence factor and plane strain ratio (PSR), the calculation model of displacement-dependent earth pressure on flexible walls of foundation pit considering spatial effects is further proposed. And the displacement-controlled solutions of earth pressure under different boundary conditions are obtained. The proposed solution is verified by numerical simulations and reported test data of foundation pit and shows good agreement. The traditional 2D earth pressure theory underestimates and overestimates the active and passive earth pressure in the corner effect area of the excavation, respectively. Through parameter analysis and discussion, the parameter effects on 3D earth pressure are ranked as soil cohesion > soil friction angle > wall friction angles. The results of the study provide an important theoretical basis for the 3D design calculation of foundation pits. [ABSTRACT FROM AUTHOR]

During the normal operation of the Huangdeng Hydropower Station's reservoir, many tensile cracks were observed on the surface of the bank slope below the elevation of 1805 m along the highway, causing significant damage to local residents' production and lives. On-site geological investigation, surface and inclinometer displacement monitoring were carried out, and the deformation characteristics of the Cheyiping landslide were analyzed. A controllable intensity rainfall simulator and a reservoir water level variation simulation system were designed in our laboratory. The lower section of the highway along the river in Cheyiping small village was chosen as the prototype, and a centrifuge model test of the reactivation of the Cheyiping ancient landslide induced by rainfall and reservoir water level fluctuations was performed. The characteristics of landslide deformation, pore water pressure, and earth pressure variation under the influence of rainfall and reservoir water level changes are investigated. The thorough analysis revealed that, even if the sliding surface is not deep, the sudden drop in reservoir water level remains the primary controlling factor of slope sliding. Because the permeability of the deposit is low, rainfall has a minor impact on this ancient landslide. The experimental results can be used to guide slope prevention and reservoir management in the Huangdeng Reservoir area. [ABSTRACT FROM AUTHOR]

Shield tunnelling presents numerous potential risks particularly in complex geological environments. In this study, we propose a novel fuzzy model for assessing the risk of tunnelling in soil-rock mixed strata. The proposed model incorporates the fuzzy setpair analysis (FSPA) method into fuzzy c-means (FCM) clustering to overcome the limitations of conventional data normalisation. Data pertaining to tunnelling machine, deformation, and vibration are employed to construct an index system using mutual information algorithms for feature selection. The intercriteria importance though intercriteria correlation is employed to weight the indicators, and the FSPA method is adopted to calculate the connection number. Subsequently, the results are classified by the FCM with a modified objective function that considers the importance of risk indicators to derive the risk level of each ring in real time. The proposed model is applied to a case study of a shield tunnelling project in Guangzhou, China. The analysis results indicate a higher risk level from Ring 1572 onwards, which necessitates a judicious regulation of the thrust force and earth pressure. This novel method provides a practical and reliable tool for guiding risk decisions during the tunnel construction. [ABSTRACT FROM AUTHOR]

Coir-geotextile plays a significant role in the reinforcement of red clay foundation. The present study was envisaged to investigate the effect of the length, reinforced depth, and embedment depth of the first layer of coir-geotextile as well as the vertical spacing of coir-geotextile on the bearing capacity and distribution of Earth pressure along the depth of a red clay foundation using plate loading tests and numerical simulation. The results revealed that the bearing capacity of the red clay foundation increased with an increase in the length of coir-geotextile and the reinforced depth of coir-geotextile. The bearing capacity of the red clay foundation was inversely proportional to the embedment depth of the first layer of coir-geotextile and the vertical spacing of the coir-geotextile. The optimal length, reinforced depth, and embedment depth of the first layer of coir-geotextile were found to be 3B , 2B , and 0.25B , respectively (B is the width of strip footing). The optimal vertical spacing of the coir-geotextile was found to be 0.25B. The Earth pressure in the red clay foundation reinforced with the coir-geotextile showed a gradual reduction along the depth of foundation. However, it dropped slowly within the reinforced depth of coir-geotextile due to the stress concentration caused by the coir-geotextile and dropped faster outside the reinforced depth of coir-geotextile. The red clay foundation reinforced with the coir-geotextile failed by punching. Based on the punching failure, the calculated values of the bearing capacity ratio of the simplified calculation method were observed to be close to the measured values in the model tests. The results obtained by the small-scale model tests in the present study can provide a reference for the bearing capacity and Earth pressure distribution of the red clay foundation reinforced by coir-geotextile under similar test conditions. [ABSTRACT FROM AUTHOR]

SUMMARY: Atmospheric pressure changes on Earth's surface can deform the solid Earth. Sorrells derived analytical formulae for displacement in a homogeneous, elastic half-space, generated by a moving surface pressure source with speed $c$. Ben-Menahem and Singh derived formulae when an atmospheric P wave impinges on Earth's surface. For a P wave with an incident angle close to the grazing angle, which essentially meant a slow apparent velocity $c_a$ in comparison to P- ($\alpha ^{\prime }$) and S-wave velocities ($\beta ^{\prime }$) in the Earth ($c_a \ll \beta ^{\prime } \lt \alpha ^{\prime }$), they showed that their formulae for solid-Earth deformations become identical with Sorrells' formulae if $c_a$ is replaced by $c$. But this agreement was only for the asymptotic cases ($c_a \ll \beta ^{\prime }$). The first point of this paper is that the agreement of the two solutions extends to non-asymptotic cases, or when $c_a /\beta ^{\prime }$ is not small. The second point is that the angle of incidence in Ben-Menahem and Singh's problem does not have to be the grazing angle. As long as the incident angle exceeds the critical angle of refraction from the P wave in the atmosphere to the S wave in the solid Earth, the formulae for Ben-Menahem and Singh's solution become identical to Sorrell's formulae. The third point is that this solution has two different domains depending on the speed $c$ (or $c_a$) on the surface. When $c/\beta ^{\prime }$ is small, deformations consist of the evanescent waves. When $c$ approaches Rayleigh-wave phase velocity, the driven oscillation in the solid Earth turns into a free oscillation due to resonance and dominates the wavefield. The non-asymptotic analytical solutions may be useful for the initial modelling of seismic deformations by fast-moving sources, such as those generated by shock waves from meteoroids and volcanic eruptions because the condition $c / \beta ^{\prime } \ll 1$ may be violated for such fast-moving sources. [ABSTRACT FROM AUTHOR]

The Silvertown Tunnel is a new twin‐bore road tunnel under the River Thames in the east of London that increases the river crossing capacity in this area and provides enough clearance for the zero‐emission double‐decker buses. It is being delivered by Riverlinx CJV on behalf on Transport for London (TfL). The overall project consists of tunnel approach ramps at both portals, cut and cover tunnels, and two 1.1 km‐long bored tunnel sections as well as highway connections including a new footbridge and service buildings for operating the tunnel from either end. In this article, the approach and challenges of mechanised tunnelling including the river crossing in a high‐density area, with a large‐diameter earth pressure balance (EPB) machine in mixed‐face conditions, are presented. The Tunnel Bori selection based on the geological and geotechnical information is evaluated and compared to the experience during execution of tunnelling. In detail, the actual EPB drive is evaluated by considering the face pressure support, predicted surface settlements and planned cutterhead maintenance. [ABSTRACT FROM AUTHOR]

This paper develops a general and complete solution for the undrained cylindrical cavity expansion problem in nonassociated Mohr‐Coulomb soil under nonhydrostatic initial stress field (i.e., arbitrary K0${{K}_0}$ values of the earth pressure coefficient), by expanding a unique and efficient graphical solution procedure recently proposed by Chen and Wang in 2022 for the special in situ stress case with K0=1${K}_{0}=1$. It is interesting to find that the cavity expansion deviatoric stress path is always composed of a series of piecewise straight lines, for all different case scenarios of K0 being involved. When the cavity is sufficiently expanded, the stress path will eventually end, exclusively, in a major sextant with Lode angle θ in between 5π3$\frac{{5\pi }}{3}$ and 11π6$\frac{{11\pi }}{6}$ or on the specific line of θ=11π6$\theta = \frac{{11\pi }}{6}$. The salient advantage/feature of the present general graphical approach lies in that it can deduce the cavity expansion responses in full closed form, nevertheless being free of the limitation of the intermediacy assumption for the vertical stress and of the difficulty existing in the traditional zoning method that involves cumbersome, sequential determination of distinct Mohr–Coulomb plastic regions. Some typical results for the desired cavity expansion curves and the limit cavity pressure are presented, to investigate the impacts of soil plasticity parameters and the earth pressure coefficient on the cavity responses. The proposed graphical method/solution will be of great value for the interpretation of pressuremeter tests in cohesive‐frictional soils. [ABSTRACT FROM AUTHOR]

The current active earth pressure calculation theory cannot take into account the influence of the foundation inverse slope. For the translational mode retaining wall in this paper, taking cohesive backfill as the research object, the clay within the crack depth range is equivalent to uniform overload, using the upper limit theory, establishing the energy conservation equation of the velocity field and force, and the analytical formula of the tensile crack depth and the slip surface of the cohesive backfill being obtained. By taking into account the soil arching effect, setting up the static equilibrium equation by horizontal layer analysis, deriving the active earth pressure calculation expression of cohesive backfill, it is possible to consider the influence of the basement inverse slope. In the case of cohesionless backfill, the formula can be reduced to the theoretical solution. By comparing the calculated results with the experimental values and relevant theories, this can verify the applicability of the formula. The result of research shows that, with the increase of the basement inverse slope angle, the development of the tensile crack will be promoted, the dip angle of the slip surface changes little, and the resultant force and overturning moment will decrease, which is conducive to the antisliding stability and antioverturning stability of the wall, reducing the project cost. The active earth pressure distribution of cohesionless backfill is independent of whether there is an inverse slope in the basement. The theoretical formula obtained in this paper can be used as reference for the design of the retaining wall. [ABSTRACT FROM AUTHOR]

The failure mode of the soil behind the rigid support structure of excavations parallel to tunneling was simulated using the adaptive finite-element limit analysis method. This study showed the effects of tunnel diameter, tunnel construction clear spacing, excavation insertion ratio, and soil strength on the failure mode of the soil. Based on the simulated results obtained from finite-element software, a stress field was constructed for the portion above the horizontal plane at the bottom of the excavation support structure. Three types of boundary value problems were solved based on different regional divisions. Eventually, the stress state at any point within the plastic zone was calculated, providing the active earth pressure on the support structure adjacent to the tunnel during its construction. A comparison between the stress characteristic method calculation results and the finite-element simulation results showed consistency, confirming the efficiency and accuracy of the stress characteristic method in calculating the earth pressure on the support structure of excavations parallel to tunneling. [ABSTRACT FROM AUTHOR]

The presence of convex corners will affect the earth pressure calculation, but there is a paucity of studies on calculating the ground pressure of convex corners in excavation engineering. To address this issue, equilateral convex corners are divided into two types according to the relative relationship between the side length size of equilateral convex corners and the excavation depth, and their respective earth pressure calculation model is established. The microelement static equilibrium equation is set by the horizontal layer analysis method, and then the equations for calculating active earth pressure strength, active earth pressure, and active earth pressure acting points on the equilateral convex corners are derived. The example analysis and comparative Plaxis three-dimensional (3D) finite-element verification show that the friction angle in the soil is an important factor in distinguishing between two kinds of equilateral convex corners, and the active earth pressure strength, the active earth pressure, and the acting point will be affected by the side length and rotation angle, where the influence of the side length on the active earth pressure strength is relatively small. The active earth pressure may show a variety of different variation laws affected by soil parameters. The acting point will move in both directions of the plane with the change of side length and rotation angle. The theoretical calculations of active earth pressure agree with the results of three-dimensional simulations, which may explain the rationality and practicality of the theoretical method in this paper. [ABSTRACT FROM AUTHOR]

The coherence of axial force between steel struts in excavation (axial force coherence) is an important factor affecting the axial force control of servo struts. To understand the law of axial force loss of adjacent struts caused by servo struts loading, this paper proposes a calculation method based on the theory of nonlimiting earth pressure. First, the diaphragm wall is simplified to a simply supported beam with both endpoints free horizontally, the soil on both sides of the diaphragm wall is divided into n small sections (n as big as possible) along the depth direction, and the average nonlimiting earth pressure combined force within each section is calculated. Second, a system of nonlinear force-displacement equations is constructed by applying the "graph multiplication" method to calculate the combined nonlimiting soil pressure and deflection of the wall from the axial force of the servo steel strut at each level. The Newton–Raphson method is applied to obtain a recursive equation for the wall displacements. The accuracy of the method is verified by comparison with field measurements. Then, based on the method in this paper, the effect of prestressing and adjustment on the axial variation of each strut course is investigated. The method can provide a reference for the loading scheme of servo steel struts in deep excavation in soft-soil areas. [ABSTRACT FROM AUTHOR]

This study investigated active and passive lateral earth pressure in the presence of anisotropic seepage conditions. The soil was assumed to be granular and fully saturated. Three methods were used to solve the problem: (1) the upper bound limit analysis method (UBM); (2) upper and lower bound solutions of finite-element limit analysis (FELA); and (3) the stress characteristic method (SCM). The proposed analytical solution for the UBM employed the logarithmic spiral slip surface. The lateral earth pressure coefficients for the active and passive cases were calculated and presented, considering variations in the vertical-to-horizontal hydraulic conductivity ratio, friction angle, and soil–wall interface friction angle. The obtained results for the active and passive cases agree with those of previous studies. The results of the SCM showed that in the presence of seepage, the distribution of stress on the soil–wall interface is nonlinear. In addition, the failure zone obtained from different methods was compared and examined. The failure patterns obtained from the SCM and FELA were almost identical. [ABSTRACT FROM AUTHOR]

During tunnel construction with earth pressure balance (EPB) shield machine, the machine operators determine the attitude correction parameters depending only on their own experiences. Inappropriate parameter setting may lead to more and more deviation of equipment attitude, delay of construction period, or even ground collapse. An attitude correction method for an EPB shield machine is proposed in this study to assist new machine operators in determining suitable operating parameters in advance considering the previous correction experience. The proposed method first reconstructs the tunneling parameters and attitude parameters according to experienced drivers. Then, using these parameters, an association model based on multiple machine algorithms is established to refine the important association rules of EPB shield machine attitude. Finally, the optimal range of deviation correction parameters corresponding to different attitude deviation is generated. This assisted attitude control method was examined using the data from the Chengdu Subway project in China. Essentially, this study can be helpful for the equipment attitude correction and the determination of correction parameters, paving the way for ideal track driving in harsh tunneling environments. [ABSTRACT FROM AUTHOR]

To investigate the effect of in-pit vehicle load on the stability of the pit against overturning, a long tunnel foundation pit project in Suzhou is used as a case. In-pit vehicle load effects are modelled using the improved equivalent soil thickness method. Through the utilization of the upper limit theory of limit analysis of finite soils and considering the spatial distribution of suction force in the matrix of unsaturated soils, a deduced method for calculating the stability coefficient of the unsaturated finite soil pit against overturning under vehicle load is established. The results indicate that in-pit vehicle load favours pit stability against overturning relative to conventional outside-pit vehicle load. The change in pit stability is more significant when the soil rupture angle is corrected by using the improved equivalent soil thickness method. The increased suction in the unsaturated soil matrix contributes to the pit's stability against overturning. When calculating the stability coefficient against overturning, the finite earth pressure theory proves to be more realistic than the classical earth pressure theory. The results of this study can provide a valuable reference for similar types of pits to prevent overturning. [ABSTRACT FROM AUTHOR]

The control of surface heaving has been of interest in major applications of compaction grouting such as ground improvement and settlement compensation works. Some studies generalize compaction grouting as heave-inducing and thus the corresponding soil improvement increases with depth, while others do not. Effective planning of compaction grouting requires assessment of whether it is heave-inducing and understanding the effects of confining stresses on its mechanisms and effectiveness. Unfortunately, little effort has been made in this regard. The current paper addresses these issues through physical modeling of compaction grouting using a large-scale double-wall calibration chamber and injection system capable of injecting the stiff compaction grouts. The results of twenty-one test cases conducted under well-controlled conditions are presented, discussed, and compared with the results of actual compaction grouting. The confining stresses as represented in terms of the vertical stress (σV) and coefficient of earth pressure at rest (K0). The presented results and discussions show the reliability of the adopted modeling. Empirical correlations that engineers can use to predict the occurrence of surface heaving as well as pre-heaving compression of soil, surface heave, creep deformation, and residual increase of K0 for given confining stresses are newly introduced. The results of developed correlations show good comparison with those of actual compaction grouting. Implications for actual compaction grouting are also presented. [ABSTRACT FROM AUTHOR]

In this study, asymmetrical and symmetrical pile length model tests were performed to investigate the interaction between retaining piles with asymmetrical excavation. The deformation, earth pressure, and bending moment of the retaining pile on both sides were measured during asymmetrical excavation. The numerical analysis using PLAXIS 2D was validated by comparing the results with experimental data. Through numerical studies, the horizontal displacement, bending moment, and earth pressure of the piles were studied with asymmetrical excavation in terms of three design factors: asymmetrical pile length, pile stiffness, and bracing stiffness. Results show that asymmetrical excavation induces a "push-back effect", and the pile-top displacement on the shallower side decreases from 0.54 mm to 0.49 mm and from 0.47 mm to 0.42 mm for asymmetrical and symmetrical pile lengths, respectively. The deformation, earth pressure, and bending moment of the retaining pile develop asymmetrically during asymmetrical excavation. The lateral earth pressure distribution was closely related to pile deformation, while the pile bending moment was related to the lateral earth pressure and the axial force of the bracing. With a decrease in the retaining pile stiffness and an increase in the bracing stiffness, the deformation mode of the retaining pile transitioned from a cantilever type to a bulging type, which further influences the distribution of earth pressure on the retaining pile and the distribution of the pile bending moment. For asymmetrical excavation, a deformation-based asymmetrical design for the retaining pile length is recommended to make good use of the push-back effect. [ABSTRACT FROM AUTHOR]

This work introduces a theoretical framework for determining the active non-limit earth pressure of cohesive soil on a base-rotating rigid wall. The framework incorporates the nonlinear Mohr–Coulomb failure criterion, the Duncan–Chang hyperbolic stress–strain relationship, the log-spiral potential failure surface in retained soil, and a horizontal slice method for the earth pressure evaluation. The proposed method allows quantitative determination of displacement-dependent earth pressure and its distribution along the wall back. Practical wall movement in the at-rest state is considered, and the tension crack depth near the soil surface is calculated based on the soil tensile strength cut-off. Analysis results highlight the nonlinear variation of the mobilized soil shear strength vertically, influenced by the nonlinear Mohr–Coulomb failure criterion. As the wall rotation increases, the earth pressure follows a convex parabolic distribution with a tension failure zone near the soil surface and no pressure at the wall base. The resultant of the earth pressure reduces and its application point descends while the tension crack depth expands, though always remaining less than the Rankine's earth pressure. A practical example shows that the at-rest earth pressure can be up to 1.3 times greater than the active earth pressure, with the resultant application point approximately 5% higher. Parameter study exhibits that the active non-limit earth pressure correlates nonlinearly with the soil ultimate tensile stress and nonlinear coefficient, particularly as wall movement increases. Active non-limit earth pressures vary within 86% across different soil cohesions, and up to 50% under varying ultimate tensile stresses and nonlinear coefficients. Overturning safety factors of the wall in the active non-limit state differ significantly from those in the at-rest state, especially under varying soil cohesions. [ABSTRACT FROM AUTHOR]

Excavations for underground structures, such as working shafts, underground grain silos, and parking garages, are characterized by uniformity, consistent dimensions, large quantities, and strict timelines. Prefabricated recyclable supporting structures (PRSS) are gaining attention over traditional retaining structures due to their standardized design, efficient construction, and reusability, which suit such excavations better. To validate their performance, full-scale tests are conducted to analyze the deformation and stress characteristics of PRSS. The results show that the average maximum lateral displacement of supporting pile is 0.07% of the excavation depth (He), roughly half that of steel plate. Differences in ground surface settlement behind steel plates and the supporting piles are not as significant as those in their lateral displacements. While the displacement of the supporting piles is insufficient to induce soil movement into the active limit state on the non-excavation side, the circular excavation's arching effect reduces the earth pressure on this side of the supporting piles below the active earth pressure limit. Furthermore, the earth pressure acting on the steel plates is lower than that acting on the supporting piles, suggesting the presence of a soil arching effect between two adjacent piles. These findings offer valuable insights for guiding the construction of PRSS. [ABSTRACT FROM AUTHOR]

The emerging upward shield method (USM) for constructing vertical shafts has been used in various projects, including the Midosuji utility tunnel in Japan. A scaled-down model testing system, featuring a geometric similarity ratio of 1:30, was developed specifically for studying the USM. This system incorporates sand inflow control, propulsion control, data acquisition, and water level control. It facilitates detailed observation and recording of parameters such as vertical displacement of surface soil layers, support force at the excavation face, and earth pressure within the model box. Consequently, it enables investigation into the excavation face instability process, modes, and the formation and evolution of the soil arch zone above the excavation face during upward shield tunneling. Additionally, through the application of particle image velocimetry (PIV) technology and GeoPIV-RG software v1.1, quantitative analysis of soil displacement fields during excavation face instability is conducted, capturing microscopic displacements and deformations of soil planes. This approach more accurately elucidates the accuracy of understanding the dynamic response of soil. Pre-test research using the model testing system explores the variation patterns of excavation face load displacement, vertical earth pressure within the failure zone, surface displacement, and internal soil displacement during the instability process. Analysis reveals that excavation face load variation typically progresses through three stages: rapid growth, slow growth, and descent. Moreover, vertical earth pressure shifts upward in tandem with excavation face displacement, while overall surface displacement initially shows slight settlement followed by accelerated uplift. [ABSTRACT FROM AUTHOR]

Jinan City in China is known for its abundant spring water, and the protection of underground spring water transport channels is a key issue that needs to be paid attention to in Jinan subway construction. In areas where underground spring water transport channels are easily disturbed, when the shield tunnel passes through a composite formation with a permeable layer in the middle and an impermeable layer in the upper and lower parts, the underground spring water transportation channel is blocked, the spring veins are damaged, and the underground spring water is blocked in the upstream, resulting in an increase in the water pressure difference on both sides of the tunnel. In this paper, based on the working principle of a new type of pipe segment with a diversion function, a diversion function pipe model test box is designed and fabricated. Using this model box, the working state of the diversion function pipe segments is simulated. An earth pressure box and pore water pressure gauges are embedded in the model box to measure the earth pressure and pore pressure around the pipe under seepage unsymmetrical pressure. Strain gauges are attached in a circular shape on the inner side of the pipe to measure and calculate the strain and stress of the pipe. Through model tests, the effective repair of the diversion pipe on blocking groundwater flow and the relief effect of the unsymmetrical pressure of the pipe are verified. [ABSTRACT FROM AUTHOR]

The increasing number of private cars, public transportation vehicles, and pedestrians, as well as the absence of adequate space for these ground amenities, are one of the primary causes of traffic congestion and accidents in the Kathmandu Valley. Investigations have indicated that the Kathmandu Valley has the greatest traffic accidents despite the heavy presence of the government and its agencies there. Most teens and young adults suffer injuries while using motor vehicles. The study's primary objective is to foresee and prevent such complications by planning for sufficient subsurface infrastructure (a cut‐and‐cover rectangular tunnel) for the Kathmandu Valley's transportation network. The overlying pressure, lateral earth pressure, live load, uplift pressure, and live surcharge are some of the forces acting on the tunnel, creating unique stress and moment zones. The tunnel meets the following geometric requirements: (a) Each of the tunnel's two cells has a clear span of 10 m and a clear height of 5.5 m. The side walls, inner walls, top slab, and bottom slab are all 700 mm thick. Soil has built up to a height of 4 m over the tunnel's roof. The analytical method is used in the tunnel segment's analysis. Furthermore, the designed tunnel has been evaluated for stability, considering the deflection and shear resistance. The analysis indicates that the tunnel meets the stability requirements. This implies that the structure is capable of withstanding the applied forces without excessive deflection. Non‐linear dynamic time history analyses of the El Centro earthquake and the Gorkha earthquake were computed. From the El Centro earthquake, the maximum displacement was 23.63 mm at 10.59 s, and from the Gorkha earthquake, the maximum displacement was 16 mm at 0.19 s for the modeled structures. [ABSTRACT FROM AUTHOR]

In this study, the effects of soil spatial variability on the behaviour of the embankment supported with a combined retaining structure (CRS) were investigated. The numerical model of the CRS embankment was established and validated with the field data. An application programming interface (API) was developed to deal with the data exchanging issue between the numerical model and the spatial variability characterization model. Based on the verified numerical model and the API, the probabilistic analysis with 500 Monte Carlo simulations was automatically computed. Three influencing factors of the retained soil (the mean of the friction angle, the variation of the friction angle and the vertical correlation length of the random field) are analysed by parametric analysis. The results show that the vertical correlation length of the random field is most important in the earth pressure calculation process, while the mean of the friction angle is the factor with least impact. On the whole, the spatial variability of soil properties has minimal impact on the distribution and magnitude of earth pressure behind the retaining structure. [ABSTRACT FROM AUTHOR]

A series of centrifuge tests was conducted to explore the deformation mechanisms and earth pressures mobilised in loose and dense sand for a complete set of passive movement modes of a rigid retaining wall: rotation about the top and base and translation. Sand deformations were measured by particle image velocimetry and earth pressures were observed by a Tekscan pressure mapping system. Simplified linkages between wall displacements, sand strains and earth pressures were built. Superposition of such results would allow designers to predict retaining wall behaviour in sand during the construction sequence as well as ultimate collapse in a mobilisable strength design procedure. [ABSTRACT FROM AUTHOR]

Quantifying the earth pressure acting on retaining structures is essential for a number of engineering applications, including the assessment of damaged structures. In response to the widespread corrosion found in many cantilever retaining walls in Switzerland, this study investigates the evolution of the earth pressure acting on a retaining wall rotating about its base: the dominant deformation mode for such structures. In a controlled setup, a scaled cantilever retaining wall is first backfilled and then subjected to rotation about its base. An extensive experimental program was conducted to evaluate the effects of different soil properties, packing densities, and initial soil stresses on the earth pressure during the life of a wall. Accurate measurements allow the stick-slip behavior typical of granular soils to be observed. An analysis of this behavior suggests that its impact on the practical safety assessment of retaining walls is negligible. Tests performed under 3D conditions show how local damage to a section of the wall results in a lower active earth pressure value on that section due to stress redistribution, which causes an increase in pressure on adjacent sections. It is also observed how the initial earth pressure acting on retaining walls after backfilling results from a perturbed stress state due to wall deflection and wall friction. Its distribution is bilinear for uncompacted soil and nonlinear for compacted soil. Loosely packed soil exerts higher pressures than densely packed soil. The unloading process shows the expected behavior of loose and dense soil: it is slower and monotonic in loose soil and faster in dense soil, where the initial unloading is followed by reloading due to softening in the backfill. The experimental results are available in a public repository and can serve as a resource for the development and validation of improved verification procedures. [ABSTRACT FROM AUTHOR]

For one of the famous and widely investigated intermediate valence compound YbB12, the experimental studies of the pressure effect on magnetic susceptibility χ (P) were carried out under helium gas pressure P up to 2 kbar at fixed temperatures 78 and 300 K using a pendulum type magnetometer. The measurements show a slight increase in susceptibility under pressure, which is consistent in sign with similar literature data for other ytterbium compounds with intermediate valence of Yb ions. Based on a model analysis of experimental data, the pressure derivative of Yb valence in YbB12 was estimated for the first time, the value of which is in line with the general trend of the valence behavior under pressure in rare earth compounds exhibiting intermediate valence. [ABSTRACT FROM AUTHOR]

Yang, S.M. and Lee, J.K., 2024. Evaluating the geoengineering performance of a gravity multiblock quay wall and jet-grouting on marine clayey soils along the Korean coastline. Journal of Coastal Research, 40(4), 672–682. Charlotte (North Carolina), ISSN 0749-0208. Jet-grouting has been widely used as a ground improvement method in several fields of geoengineering, but most of the case studies have focused on embankments and excavations. This paper describes the performance of a gravity block-type quay wall in the southwest coast of Korea where the underlying soft clayey soils were improved by jet-grout columns. The scheme and properties of jet-grouting and the construction history and measured behavior of the wall-soil system are presented. A finite element analysis was conducted to estimate the settlement, lateral displacement, and horizontal earth pressure of the quay wall. The computed results compare well with the field data during and after construction. The effect of area replacement ratio, quantifying the degree of ground improvement, on the response of the quay walls was also investigated. The field and numerical results show that the jet-grout columns enhanced the performance of the block-type quay wall over soft soils. [ABSTRACT FROM AUTHOR]

Nonlocal regularization is frequently used to resolve the mesh dependency issue that is caused by strain softening in finite-element (FE) simulations. Some or all variables that affect strain softening are assumed to depend on the local, neighboring, or both in this method. The weight function is the main component of a regularization method. There are three widely used weight functions, which include the Gaussian distribution (GD), Galavi and Schweiger (GS), and over-nonlocal (ON) functions. All of them could alleviate or eliminate the mesh dependency in simple boundary value problems (BVPs), such as plane strain compression; the evaluation of their performance in real-world BVPs is rare. A detailed comparison of these functions has been carried out based on an anisotropic sand model that accounts for the evolution of anisotropy. The increment of void ratio is assumed nonlocal. All functions give mesh-independent force–displacement relationships in drained and undrained plane strain compression tests. The shear band thickness shows a small variation when the mesh size is smaller than the internal length. None could eliminate the mesh dependency of shear band orientation. The GS method is the most efficient in eliminating the mesh dependency in the strip footing problem. The ON method could give excessive overpredictions of the volume expansion around strip footings, which leads to unrealistic low reaction forces on strip footings at large deformations. All three weight functions give mesh-independent results for the earth pressure that acts on a retaining wall. [ABSTRACT FROM AUTHOR]

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The seismic behavior of earth retaining structures continues to remain a critical consideration in engineering design and lessons learned from the full-scale performance of retaining walls during earthquakes are invaluable. The observed performance of several retaining walls in the area affected by the 2014 Cephalonia, Greece, earthquakes is presented. Subsequently, the case of measured kinematic response (i.e. residual seismic movements) of a 6.0 m high concrete gravity-type "retaining wall-backfill" system, which displaced during the earthquake, but remained functional is presented. The recording of a strong motion station—located at a distance of less than 200 m from the wall—was used to describe the horizontal earthquake ground excitation. The inertial response of the "wall-backfill" system was analyzed through a finite element numerical model based on in-situ shear wave velocity measurements and values of mechanical soil properties back-calculated from the measured kinematic response of the system to the particular earthquake. The selection of soil material values of stiffness and strength was based on the results of post-earthquake Vs-depth measurements at the wall site. The measured kinematic response of the "wall-backfill" system was compared to predictions of several published empirical relations. The empirical relations were all found to overpredict the observed displacements and in some cases, significantly. The derived numerical model of the "wall-backfill" system was subsequently used to investigate (a) the magnitude and distribution of seismic earth pressures on the wall as well as the backfill settlements, and (b) the beneficial phase difference developed between the peak values of wall inertia and active earthquake thrust increment during the particular earthquake event. The results of this case history agree well with previously published results concerning the inertial response (seismic earth pressures and phasing issues) for walls retaining cohesionless and cohesive backfills. [ABSTRACT FROM AUTHOR]

Secant pile walls (SPWs) are frequently employed as temporary excavation support systems in urban areas; thus, they are useless once permanent foundations and basements have been constructed. Recently, attempts have been made to employ these walls to bear axial loads and lateral earth pressure, which may have significant potential benefits. Unfortunately, the shortage of research that recognizes them as bearing elements, especially numerical studies, has prevented this approach from reaching the final design and implementation stage. Thus, the primary objective of this research was to calibrate a finite element model to depict the performance of axially loaded SPW and extend the finite element analysis by including key factors and additional trials that may impact the performance of the axially loaded SPW. This research investigated various aspects to describe SPW behavior, including the maximum axial capacity of the SPW (Pmax), normalized horizontal deflection (δh/Ht%), normalized ground settlement (δvg/Ht%), the normalized vertical deflection of the SPW (δvw/Ht%), the normalized pivot point location (ε′/He) and settlement influence zone (Do). Several parameters, such as normalized penetration depth (He/Hc), sand relative density (Dr), surcharge load density (Wsur), and wall rigidity (Ht/Dp), were studied and examined in relation to these aspects. Additionally, 224 axially loaded SPW trails were performed as part of a parametric study. The findings demonstrated that the proposed FEM could depict the performance of the experimental model with fair accuracy under the effect of the axial and lateral loads. The effects of the investigated aspects on the Pmax were also discussed in detail. Also, using linear and non-linear regression analysis, the data from the parametric analysis was utilized to create rational relations between the various parameters. The best-achieved mathematical models for predicting the Pmax were also represented in graphical forms. Moreover, these graphs can be a useful and fast tool for civil and geotechnical engineers to predict the maximum axial capacity of an SPW according to the different variables. [ABSTRACT FROM AUTHOR]

This study comprehensively analyzes seismic active earth pressure estimation for hunched retaining walls. The analysis utilizes the horizontal slices method within the modified pseudo-dynamic framework and incorporates depth-dependent dynamic parameters for the backfill soil. The friction angle of the backfill soil varied between 30° and 45°, while the hunch angle of the retaining wall increased from 0° to 20°. The findings of this study demonstrate that the use of hunched retaining walls results in a significant reduction in active earth pressure. In both static and dynamic cases, reductions of up to 23% and 18%, respectively, compared to vertical walls, were observed. Notably, this reduction is more pronounced for smooth walls under static conditions than for rough walls under dynamic conditions. The estimated active earth pressures for both vertical and hunched walls in static and dynamic scenarios closely align with those reported in the literature. Additionally, an empirical equation based on an artificial neural network model, utilizing the numerical analysis result, is proposed to establish a relationship between the investigated design parameters and the active earth pressure coefficient. The proposed equation demonstrated a high coefficient of determination (R2) value of 99.78% when compared to the numerical results. This study's outcomes provide valuable insights and a tool for practicing engineers in the field. [ABSTRACT FROM AUTHOR]