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.

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.

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.

The tensioned reinforced soil retaining wall, a novel retaining structure, utilizes either anchors or geosynthetic materials as reinforcements that contribute to load-bearing and friction within the structure. This study aims to explore the tension distribution and strain patterns in the reinforcements, and their influence on the reinforced soil retaining walls. To this end, tensile, direct shear, and pullout tests were conducted on GeoStrap@5-50 geotextile strips and TGDG130HDPE geogrids to evaluate the tensile strength and interface strength between the reinforcement and the soil. The characteristics of the reinforcement-soil interface and the deformation behavior under stress were examined, with a comparative analysis of the technical merits of the two types of reinforcements. The results indicate that both the geotextile strips and geogrids enhanced the strength of the reinforced soil, primarily by increasing cohesion. The GeoStrap@5-50 geotextile strips exhibited superior tensile strength compared to the TGDG130HDPE geogrids; the reinforcement with the geotextile and geogrids both enhanced the cohesion of the standard sand, albeit with a slight decrease in the internal friction angle, by 4.6% and 3.1%, respectively, offering enhanced mechanical properties and economic value in reinforced soil retaining wall applications.

The horizontal displacement of a reinforced-soil retaining wall is a common deformation mode of seismic damage. The horizontal displacement time history and accumulative deformation after earthquakes are important parameters for evaluating the seismic performance of a reinforced-soil retaining wall, but theoretical study on this issue is scarce at the moment. In this study, an analytical method is proposed to calculate the horizontal displacement time history of a block-faced reinforced soil retaining wall. The method is based on the pseudodynamic method and differential kinematics equations, and this method was used to calculate the reinforcement material's tensile displacement and overall displacement in the reinforced area under earthquake motion, while simultaneously taking into account the accumulative deformation. The rationality and accuracy of this method are verified through comparison with model experiments and existing theories. Besides, parameter analysis was carried out to further confirm the applicability of this method. The study shows the method takes into account the influence of the accumulated deformation, and can effectively calculate the horizontal displacement time history of the block-faced reinforced soil retaining wall under larger magnitudes. Although the calculated values are smaller than the actual deformation, they are still relatively close.

Under long-term loading, the mechanical properties of geogrids in eco-bag reinforced soil retaining walls (ERSW) gradually weaken due to creep and photo-oxidative aging. In contrast, the continuously growing roots transfer their tensile strength to soil shear strength. However, the reinforcing effect of plant roots within retaining walls is often overlooked in current research and design. This study investigated the reinforcement effect of plant roots and geogrids on ERSW stability through theoretical derivations using the Swedish circle method for roots penetrating potential sliding surface and two-wedge method for shallow roots. The results showed that their synergistic reinforcement effect affords the highest overall stability of ERSW under loading. Additionally, the compensation ability of roots was investigated by vertically loading a scaled ERSW model with palm leaves and designing 16 sets of controlled tests with two geogrid lengths, three geogrid spacings, and four root lengths. The horizontal displacement of the facing, horizontal earth pressure behind the eco-bags, and geogrid tensile strain under various conditions decrease by 5.47%, 3.71%, and 4.17%, respectively, with increases in the unit length of the geogrid, and by 3.625%, 1.411%, and 4.713%, respectively, with increases in the unit length of roots. In the three parameters, the compensation rates of the root for the geogrid length are 0.66, 0.38, and 1.13, respectively. The reduction rates of the three parameters are 34.38%, 45.26%, and 58.62% with the geogrid spacing decreasing from 30 cm to 20 cm under the no-root condition, and the rates change to 56.25%, 21.14%, and 63.22% with a geogrid spacing of 30 cm and the addition of 15 cm long roots, respectively. In the three parameters, the compensation rates of 15 cm length roots for the geogrid spacing are 1.64, 0.47, and 1.08, respectively. Therefore, roots provide a compensatory effect on geogrid strength, enhancing the long-term stability of ERSW.