Yongdong Yang

Currently, the destabilization mechanisms of slopes due to rainfall infiltration are not fully understood. We conducted physical model tests to measure displacement and pore water pressure from rainfall, using the data to validate numerical models. This study explores how rainfall intensity and duration affect these measures across loess slopes with varying steepness. The goal is to understand slope responses to different rainfall conditions. Our findings indicate that steeper gradients see modest increases in displacement and pore water pressure at the top and mid‐slope, but these increases are more pronounced at the toe. The changes at the toe and mid‐slope are driven by infiltrated rainwater volume and soil compressive behavior, while top‐slope displacement is primarily due to infiltration. Continuous deformation was observed during and after the rainfall events. Post‐rain, pressure from saturated soil at the slope's apex amplifies pore water pressure at the toe, influenced by gravitational forces and retained water pressure. This underscores the complex interactions affecting slope stability in wet conditions. Understanding loess slopes' responses can improve predictive models and mitigation strategies, reducing infrastructure and safety risks in these vulnerable areas.

The soil stabilizer of the Consolid system (content: 0%–2.46%) was used for the modification of collapsible loess. The consolidation test, compression test, collapsibility test, and strength test of modified loess were conducted. In addition, X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury injection tests were carried out to study the loess before and after modification. The results indicated that with an increase in the content of the stabilizers, the optimal water content of the modified loess increased, whereas the dry density decreased. Furthermore, as the content of the stabilizers increased, the compressibility and collapsibility of the modified loess decreased. When the stabilizer content was 0.86%, the modified loess exhibited almost no collapsibility. The unconfined compressive strength of the modified loess demonstrated an exponential relationship with the content of the stabilizers. The shear strength increased with the increase in the content of the stabilizers. When the stabilizer content reached 1.66%, the friction angle started to decrease. The microstructure analysis indicated that the cumulative pore volume of the modified loess decreased with the increase in the content of the stabilizers, which could facilitate the formation of a more stable soil structure and improve the impermeability and strength.

The instability disaster of slope engineering is the third largest geological disaster after earthquake and debris flow, and rainfall is an important factor affecting the stability of slopes. In this study, the stability of a loess slope affected by rainfall infiltration was investigated using engineering examples, an in-depth site investigation, geotechnical physical and mechanical tests, and numerical simulations. The finite element software ABAQUS was used to establish a model of the rainfall infiltration slope to analyze the slope stability after rainfall infiltration while considering the influence of the groundwater level on slope stability and evaluated the reinforcement performance of retaining wall and biological measures on loess slope under rainfall conditions. The results showed that the displacement and pore pressure at the bottom of the slope increased after a strong rainfall. The rapid rise of the water level caused increases in the displacement and pore pressure of the slope, but the slope stability improved when the water table reached 0.8 m. Further analysis shows that under the joint action of rainfall and groundwater, the slope stability can be effectively improved by using retaining wall to strengthen the slope. Under the action of rainfall, the increase of vegetation depth and density has a certain effect on the improvement of slope stability. The ryegrass and alfalfa were the most effective slope stabilization approach if the vegetation parameters and economic factors were considered.

Rainfall and surface water infiltration will affect the safety of loess slope. Ecological slope protection can protect and reinforce the surface layer of the slope by using the anchoring effect of plant root. In this study, the prevention and control technology of grass planting on loess slope in the solidified soil was studied. Heavy metal contents in the soil after addition of the stabilizer met the farmland standard at the end of the growth period. A comparison of the biomass data of different groups of solidified soil showed that the biological characteristics of plants had the best response at the mixture ratio of solidified soil of 0.86%. The shear strength of the root–soil composite increased by about 60% compared with that of plain soil at the mixture ratio of 0.86% stabilizer, and the permeability coefficient can be reduced by two orders of magnitude. Through the field engineering application, the ecological restoration test using loess soil solidified by consolid system with grass planting met the engineering requirements, with clear soil and water conservation benefits. Therefore, planting grass in solidified soil can effectively reduce the erosion of soil and improve the stability of the shallow slope.