This study investigates the mechanical performance and deformation characteristics of reinforced retaining walls constructed with stabilized silty clay and geogrid reinforcement. Laboratory tests evaluated the physical and mechanical properties of native silty clay, identifying its high water content and poor gradation as primary challenges for engineering applications. A stabilization method incorporating 2 % soil stabilizing liquid, 10 % densifying powder, and 4 % Portland cement was optimized to enhance clay compaction, shear strength, and compressive strength. Model experiments were conducted under varying wall configurations, including natural slopes, stabilized retaining walls, and reinforced stabilized walls with different slope ratios. Results show that the combination of stabilization and reinforcement significantly improved load-bearing capacity, minimized vertical settlement, restricted horizontal displacement, and reduced lateral earth pressure. Comparative analysis of slope ratios revealed that gentler slopes enhanced deformation resistance and reduced geogrid strain. These findings offer practical insights and theoretical support for designing efficient retaining wall systems using stabilized silty clay.

Three approximate analytical solutions for the problem of the seismic response of two rigid cantilever walls retaining a transversely isotropic poroelastic soil layer over bedrock are presented under conditions of plane strain and time harmonic ground motion. These approximate solutions come as a result of various reasonable simplifications concerning various response quantities of the problem, which reduce the complexity of the governing equations of motion. The method of solution in all the cases is the same with that used for obtaining the exact solution of the problem, i.e., expansion of response quantities in the frequency domain in terms of sine and cosine Fourier series along the horizontal direction and solution of the resulting system of ordinary differential equations with respect to the vertical coordinate in conjunction with the boundary conditions. The first approximate solution is obtained on the assumption of neglecting all the terms of the equations of motion associated with the fluid acceleration. The second approximate solution is obtained on the assumption that the fluid displacements are equal to the corresponding solid displacements. The third approximate solution is obtained as the sum of the second approximate solution for the whole domain plus a correction inside a boundary layer at the free soil. All three approximate solutions are compared with respect to their accuracy against the exact solution and useful conclusions pertaining the approximate range of the various parameters, like porosity, permeability and anisotropy indices, for minimization of the approximation error are drawn.

The retaining wall with reinforced soil is exposed to various types of loads, including static active earth pressure caused by the self-weight of the backfill soil, seismic loads due to earthquakes, vehicle/railroad loads, and cyclic loads induced by seasonal temperature changes causing contraction/expansion. To ensure the internal stability of the retaining wall, the pullout resistance of the installed geogrid must be secured. This study presents the pullout load test results for a geogrid installed in sandy soil under cyclic loading, either in displacement-controlled or load-controlled conditions. In the pullout tests, factors such as the frequency, amplitude, and number of cycles of the pullout load were varied to consider various cyclic loading characteristics. The trends in the maximum pullout resistance and the initial pullout stiffness were analyzed. The analysis showed that under displacement-controlled cyclic loading, as the amplitude increased, both the pullout resistance and stiffness significantly decreased, with the degree of decrease intensifying as the displacement amplitude increased. This trend was also observed in the analysis of changes in pullout stiffness under cyclic loading. On the other hand, under load-controlled cyclic loading, the pullout resistance and cumulative pullout displacement both tended to decrease as the frequency increased over a fixed period, while the pullout resistance decreased and the cumulative displacement increased as the amplitude increased.

This paper presents a comprehensive investigation into the role of soil permeability variation on the stability of slopes reinforced by retaining walls, with a focus on the Huizhou slope failure as a case study. The study demonstrates that rising groundwater levels diminish the Factor of Safety (FoS) for retaining walls, with stability most compromised under combined loading from adjacent soil and lightweight concrete. These findings emphasize the need for enhanced drainage or structural support in retaining wall designs subjected to elevated groundwater conditions. It integrates advanced numerical simulations, utilizing Abaqus and GeoStudio, with empirical field data to analyze the interactions between soil permeability, pore water pressure, moisture content, shear strength, and the overall stability of the slope. The dynamics of water infiltration are influenced by permeability, moisture content, and the groundwater table. These factors change the pore pressure and decrease shear strength, which causes shear failure in the slope mass. This research also looks at how surcharge loading affects slope stability. Higher permeability soils cause faster infiltration rates, leading to higher pore pressures, lower effective shear strengths, and a higher likelihood of slope failure. The opposite is true for reduced permeability, which makes drainage more difficult and ultimately leads to hydrostatic pressure building up behind retaining walls, which in turn makes the slope even more unstable. This study demonstrates the critical need for optimized drainage systems to reduce the hazards of infiltration-induced failure and the role of precise permeability evaluation in geotechnical design. Geotechnical engineers can use these results to better understand how to construct and maintain slope stabilization systems.

Focusing on a T-shape cantilever retaining wall in a liquefiable site, a series of shaking table model tests were conducted to investigate the seismic stability characteristics of the wall when using EPS composite soil isolation piles (WEP), EPS composite soil isolation walls (WEW), and backfilled natural fine sand from Nanjing (WSS). The seismic response characteristics of the model ground soil and the retaining wall for the three models were comparatively analyzed regarding the acceleration, displacement, dynamic earth pressure and excess pore water pressure ratio. Moreover, the seismic performance of anti-liquefaction measures in the liquefiable ground with EPS composite isolation structures were discussed from the view of the phase characteristics and energy consumption. The results indicate that under the same peak ground acceleration, the excess pore water pressure in the WEP and WEW models is significantly lower than that in the WSS model. Different from WSS, WEP and WEW exhibit a segmented distribution with the buried depth in acceleration amplification factors. The embedding of isolation structures in liquefiable sites can reduce the wall sliding and rotational displacements by approximately 25%-50%. In addition, the out-of-phase characteristics of dynamic earth pressure increment are evidently different among WEP, WEW and WSS. There is an approximate 180 degrees phase difference between the dynamic earth pressure behind the wall and the inertial force in the WEP and WEW models. EPS composite soil isolation structures show good energy dissipation characteristics, and especially the isolation wall is better than isolation pile. The displacement index of WSS retaining wall is significantly larger than that of WEW and WEP, indicating that EPS composite isolation piles and wall play an important role in the mitigating damage to the retaining wall. This study can provide references for the application of isolation structures in the liquefiable ground soil regarding the seismic stability.

In the loess mountainous area, many reinforced soil retaining walls are constructed with corners, unlike linear embankment fill retaining walls, due to new site developments. The upper sections of these walls are more prone to deformation and damage at the corners due to industrial plant (rectangular loads) or road (strip loads) construction, affecting their service life. To investigate the effects of rectangular and strip load types on the corners of folded-angle reinforced earth retaining walls, a physical model with both folded and vertical angles was established to explore soil pressure distribution and wall displacement deformation. The experimental results indicate: (1) A significant difference exists in soil pressure distribution in the transition between the corner and the straight line of the retaining wall under the two load types. Under rectangular loads, maximum vertical soil pressure occurs at the corner, decreasing towards both ends. In contrast, the retaining wall under strip loads shows no significant fluctuation, only a gradual decrease along the top back of the wall. (2) The horizontal deformation of the reinforced soil retaining wall at the corner under different loads shows a bulging shape, and the vertical deformation slows down as the load increases to 80 kPa. The macroscopic deformation cracks show a logarithmic spiral shape and are symmetrically distributed along the bisector of the corner angle. The research findings provide a theoretical basis for optimizing the design of reinforced soil retaining walls with similar folded angle structures.

A novel high-permeability counterfort retaining wall (HPRW) was proposed for improved control of rainfall-induced landslides, and its working performance and mechanism were studied by thorough numerical simulations. The numerical simulations revealed that the retaining effect of the HPRW was significantly better than that of the conventional counterfort retaining wall (CRW) under the effect of rainfall. Relative to the CRW, the pore water pressure and groundwater table decreased owing to the excellent drainage capacity of the HPRW, in turn leading to the decreases in the hydrodynamic pressure and earth pressure. Consequently, the slope deformation decreased and stability of the slope increased with the application of the HPRW. Furthermore, the stress and displacement of the HPRW and the earth pressure acting on the HPRW were lower than those of the CRW under identical working conditions. Parametric analysis indicated that the rainfall intensity, property of the sliding mass and gravel filling in the catchment tank affected the retaining effect of the HPRW and the stability of the slope to varying degrees. The results of this study can provide a significant basis for the design, application and subsequent research on the HPRW.

Deciding on the inclusion of tiers and determining the optimal number of tiers are critical considerations in the design of reinforced soil retaining walls (RSRWs). In this study, the mechanical properties of RSRWs under seismic loading are discussed in depth, with special attention paid to the influence of tiered configuration effects on the seismic performance of RSRWs. The response characteristics of these structures under seismic loading were comparatively analyzed by conducting shaking table tests of single-tiered, two-tiered, and three-tiered modular geogrid RSRWs. The results show that localized modular misalignment mainly occurs at the top of the retaining walls of all tiers, and reasonable tiered design can enhance the stability, but too many tiers may instead reduce the structural stability. The tiered reinforced soil retaining walls (TRSRWs) exhibit higher natural frequencies and damping ratios, which increase with more tiers, and the natural frequencies and damping ratios of the upper-tiered walls are always higher than those of the lower-tiered walls. The acceleration amplification effect is more significant in the upper part of the retaining wall structure, and the tiered design can reduce the acceleration amplification effect to a certain extent, but the increase in the number of tiers does not have much effect on this. The horizontal displacement of the TRSRWs shows the distribution of upper large and lower small, and the two-tiered retaining wall effectively reduces the horizontal displacement of the wall facing, whereas the three-tiered retaining wall does not have a significant improvement effect. The tiered design significantly optimizes the settlement of the retaining walls, and the number of tiers has little effect on the settlement improvement. The seismic active soil pressure increased with the peak ground acceleration and loading frequency, and the tiered design changed its distribution, and the increase in the number of tiers helped to further reduce the soil pressure. The increment of reinforcement strain in TRSRWs was lower than that in single-tiered retaining walls, and the tiered design effectively reduced the reinforcement stress, but the number of tiers had a limited effect on the improvement of this effect. The upper part of the wall in the un-tiered design is prone to overall tilt and horizontal expansion, and the deformation of the upper-tiered walls of the TRSRWs is all in a composite deformation mode, while the lowest-tiered walls are in a single deformation mode. The tiered design has a positive effect in limiting the development of potential failure surfaces in the substructure, resulting in improved stability of the substructure. The results of the study can provide a reference for the design selection of RSRWs.

One of the most crucial tasks in the design, control, and construction of urban deep excavations is ensuring the safety of the existing underground infrastructure. Deformation and settlement created by excavation may damage the adjacent tunnels. In this study, the stability of an existing triple tunnel in relation to the construction of an adjacent deep excavation is evaluated by numerical simulation using both the discrete-element method (DEM) and the finite-element method (FEM). A deep excavation supported by the retaining wall and five levels of strutting system was created adjacent to an existing triple tunnel. The excavation's width and depth were 30 and 16 m, respectively. In both discrete-element (DE) and finite-element (FE) simulations, the horizontal spacing of the triple tunnel wall relative to the retaining wall (SH) is varied between 3 and 35 m, while vertical spacing of the triple tunnel's crown from the ground surface (SV) is changed from 4.8 to 32 m. The results indicated that at a certain value of SV and with increasing the SH, the horizontal displacement of the wall decreases. The variations in the triple tunnel position significantly affected the settlement pattern. In addition, the results showed that the maximum vertical displacement occurred at the middle tunnel crown, while the lowest value of the maximum vertical displacement was found at the crown of the right tunnel. At a certain value of the vertical displacement, the wall horizontal displacement is deduced by increasing in the SH value.

In order to further analyze the mechanical and deformation characteristics of geogrid-reinforced soil retaining wall in the high backfill road section, this study experimentally investigates the effects of retaining wall slope, reinforcement layers, and reinforcement position on the bearing capacity and deformation characteristics of geogrid-reinforced soil retaining walls. The distribution of earth pressure in the reinforced soil retaining wall is also analyzed. The test results indicate that the ultimate bearing capacity of the retaining wall can be effectively improved by increasing the geogrid layers. The overall stability of the retaining wall decreases as the slope increases. When the number of reinforcement layers is consistent, the arrangement of geogrid in the upper part of the retaining wall can better control the deformation of the retaining wall and enhance the overall stability of the retaining wall. Under the vertical load, the horizontal displacement of the upper part of the wall is larger than that of the lower part, and the maximum horizontal displacement of the wall occurs at the top of the wall. The vertical earth pressure is not completely transmitted along the vertical direction but is transmitted downward along a certain diffusion angle. The growth rate of the upper earth pressure decreases gradually compared to that of the lower earth pressure as the load increases.