Shiyuan Huang

In civil engineering projects, the practice of partial excavation or backfilling of slopes often results in landslide occurrences because of the redistribution of internal stress within the slope mass. This paper presents the findings from scaled-model tests conducted to investigate the reinforcement of high-fill embankment slopes using anti-slide piles. During the filling process, data were meticulously monitored using strain gauges affixed to the pile bodies and embedded earth pressure cells. The analysis focused on the mechanical behavior, including load–displacement relationships at the pile tops, bending moments, and earth pressures. This study was designed to investigate how anti-slide piles contribute to slope stabilization and to evaluate their load-bearing behavior throughout the backfilling process. Additionally, particle image velocimetry technology was used to capture the variation patterns of the soil surface displacement field, thereby revealing soil displacement deformation and the overall failure mechanism. By integrating mechanical responses with the analysis of the soil displacement field, a more profound understanding of the pile–soil interaction mechanism was attained. This experimental method provided a comprehensive depiction of the entire process, from the initial slope movement to its eventual deformation and failure. The research indicates that a reduction in pile spacing leads to a decrease in the maximum bending moment of the pile body, thereby enhancing slope reinforcement. For the same pile spacing, the pile located on the first-level slope platform shows the smallest horizontal displacement at its top after deformation. The soil on either side of the anti-slide pile disperses outward from the pile body, with the maximum displacement occurring directly beneath the pile tip.

Conventional cast-in-place counterfort retaining walls, while widely used to support the fill body in geotechnical engineering cases, suffer from extended construction cycles and environmental impacts that constrain their usage more widely. In this study, in order to overcome these limitations, the performance of two types of innovative prefabricated counterfort retaining wall system—a monolithic design and a modular design—was investigated through physical modeling. The results reveal that failure mechanisms are fundamentally governed by the distribution of stress at the connection interfaces. The monolithic system, with fewer connections, concentrates stress and is more vulnerable to cracking at the primary joints. In contrast, the modular system disperses loads across numerous connections, reducing localized stress. Critically, this analysis identified a construction-dependent failure mode: incomplete contact between the foundation and the base slab induces severe bending moments that can lead to catastrophic failure. Furthermore, this study shows that complex stress states due to backfill failure can induce detrimental tensile forces on the wall structure. To address this, a composite soil material–wall structure system incorporating geogrid reinforcement was developed. This system significantly enhances the backfill’s bearing capacity and mitigates adverse loading. Based on the comprehensive analysis of settlement and structural performance, the optimal configuration involves concentrating geogrid layers in the upper third of section of the backfill, with sparser distribution below.

The mountainous region of Greater Sochi, including the Olympic ski-jump complex area, located in the northern Caucasus, is always subjected to landslides. The weathered mudstone of low strength and potential high-intensity earthquakes are considered as the crucial factors causing slope instability in the ski-jump complex area. This study aims to conduct a seismic slope instability map of the area. A slope map was derived from a digital elevation model (DEM) and calculated using ArcGIS. The numerical modelling of slope stability with various slope angles was conducted using Geostudio. The Spencer method was applied to calculate the slope safety factors (Fs). The pseudostatic analysis was used to compute Fs considering seismic effect. A good correlation between Fs and slope angle was found. Combining these data, sets slope instability maps were achieved. Newmark displacement maps were also drawn according to empirical regression equations. The result shows that the static safety factor map corresponds to the existing slope instability locations in a shallow landslide inventory map. The seismic safety factor maps and Newmark displacement maps may be applied to predict potential landslides of the study area in the case of earthquake occurrence.

The influence of water on the mechanical properties of rock is vital for determining the rock stability when subjected to changes of water conditions. In this paper, a series of uniaxial compression tests were conducted to investigate effects of cyclic wetting and drying on the mechanical properties of sandstone and mudstone collected from Chongqing city, China. The results showed that both elastic modulus and uniaxial compressive strength of sandstone and mudstone were reduced by wetting and drying cycles, and that the degradation rate of the two mechanic parameters of mudstone was always larger than sandstone. The parameters, including water adsorption, degradation degree of elastic modulus, degradation degree of uniaxial compressive strength, increase with the increase of the wetting-drying cycles (N). The relationship between these three parameters and the value of N + 1 could be well fitted by logarithmic curves. The average degradation degree was also used to describe the degradation of per time wetting-drying cycles. It is found that the average degradation degree of elastic modulus and uniaxial compressive strength decrease with the increase of wetting-drying cycles. Moreover, the relationships between the mechanical properties and the porosity are presented, which can be fitted by linear curves. In the cyclic wetting-drying process, the elastic modulus and the uniaxial compressive strength decreased with the porosity increasing, and the degradation rates of sandstone mechanic parameters were higher than those of mudstone.

In this study, the deformation induced by the first wetting typically referred to as wetting deformation of a sandstone–mudstone particle mixture is examined. Wetting deformation can lead to collapse-inducing cracks. The cracks may weaken the strength of the structure. To investigate the first wetting-induced deformation of the sandstone and mudstone particle mixture, three triaxial tests were conducted. Two of the triaxial tests used saturated soil and dry soil. These tests were used to calculate the strain under the condition of minimized deviator stress ratio at wetting. The third triaxial test accesses various deviator stress ratios at wetting. Additionally, the influence on axial and volumetric strain of wetting at varying levels of the confining stress and deviator stress ratios at wetting was evaluated. The wetting axial and volumetric strains were found to increase with an increased confining stress and deviator stress ratio at wetting. The relationships between the wetting axial strain and deviator stress ratio at wetting yielded a logarithmic curve for various levels of confining stress. In contrast, the wetting volumetric strain yielded a direct relationship with the deviator stress ratio at wetting for various levels of confining stress. Based on these results, two equations for predicting the wetting axial and volumetric strains are suggested.

The present study focuses on the compressibility and permeability characteristics of a crushed sandstone–mudstone particle mixture (SMPM). Two type of laboratory tests, which are compressibility–permeability test (CPT) and compressibility test only (CTO), are performed. Based on the test data, the effects of the seepage action on the compressibility and ones of the void ratio (e) on the permeability are analyzed. The rate of consolidation of the crushed SMPM is also discussed. The values of compressibility index (C_c) obtained from the CPT are greater about 1.32–4.81% than ones obtained from the CTO, but the values of preconsolidation stress (σ_p) obtained from the CPT are smaller about 2.34–9.83% than ones obtained from the CTO. The slope of fitting line of e∼logK (where K is the coefficient of permeability, and log is the logarithm to base 10), defined as the permeability index (K_c), ranges from 0.146 to 0.337 with an average of 0.226. The value of C_c/K_c, used to evaluate the rate of consolidation, ranges from 0.905 to 1.250 with an average of 1.031. The rate of consolidation of the crushed SMPM may be analyzed by Terzaghi’s theory due to the average value of C_c/K_c very close to 1.0.