Take the reservoir landslide as an example, in addition to hydrological conditions, creep properties of soils play an important role in explaining the mechanisms behind landslide movement. Although the change of this deformation over time is small, the long-term accumulation will also bring new hidden danger to the safety control of the slope. This paper takes the shallow coarse-grained soils of Qiaotoubei landslide as the research interest, improves the test method for the deficiency of not allowing the lateral deformation of the specimen in the traditional one-dimensional compression creep test, and conducts the compression creep test of coarse-grained soils by using the modified high-pressure consolidation instrument. Based on this test data, the creep property of coarse-grained soils is analyzed and a suitable creep constitutive model is selected, that is generalized Kelvin model. Then, relevant parameters are determined and FLAC3D software is used to simulate the creep deformation of the slope deposits and the stress and deformation of the lattice beams. Finally, the coupling mechanism between coarse-grained soils creep and lattice structure was analyzed based on the comparison of the calculated results with the deformation or damage in the field. Through this study, some targeted suggestions and directions for future research are proposed for the management of reservoir deposit landslides, hoping to contribute to the operational safety of the reservoir.

An analytical model is derived for predicting the flow field and stability of an unsaturated infinite slope subjected to steady infiltration. The proposed model is novel because it accounts for the hydraulic anisotropy of unsaturated soil. The governing equation for steady-state seepage in an infinite slope is established in terms of matric suction under a constant surface flux boundary condition. On the basis of the available experimental findings on the hydraulic anisotropy behavior of unsaturated soils, the relative hydraulic conductivity for a soil under unsaturated conditions with respect to the soil at saturation is postulated to be a direction-independent scalar. This postulation simplifies the governing equation to a form that is directly solvable via the relative hydraulic conductivity and the saturated hydraulic conductivity tensor. To enable sophisticated applications, an exponential law and a power law that are well established in the unsaturated soil literature are used to relate the relative hydraulic conductivity to the matric suction and the effective degree of saturation, respectively. Closed-form solutions are derived for the matric suction, the flow net (potential function and stream function), and the effective degree of saturation. Analytical solutions are also derived for the soil unit weight and overburden stress. These solutions are incorporated into the unsaturated infinite slope stability formula constructed on a suction stress-based effective stress failure criterion. Hydraulic anisotropy has been shown to directly affect the flow field and the change in matric suction, which, in turn, drastically affects the slope safety factor against shallow landslides. This finding demonstrates that neglecting hydraulic anisotropy can cause a considerable overestimation of the safety factor, resulting in an unsafe slope stability prediction. The proposed model is useful for preliminary evaluation of the long-term stability of unsaturated slopes during wet periods and the antecedent slope conditions for shallow landslide initiation under transient infiltration.

Major earthquakes and rainfall may occur at the same time, necessitating further investigation into the dynamic characteristics and responses of reinforced soil retaining walls subjected to the combined forces of rainfall and seismic activity. Three sets of shaking table tests on model retaining walls were designed, a modular reinforced earth retaining wall was utilized as the subject of this study, and a custom-made device was made to simulate rainfall conditions of varying intensities. These tests monitored the rainwater infiltration pattern, macroscopic phenomena, panel displacement, tension behavior, dynamic characteristics, and acceleration response of the modular reinforced earth retaining wall during vibration under different rainfall intensities. The results indicated the following. (1) Rainwater infiltration can be categorized into three stages: rapid rise, rapid decline, and slow decline to stability. The duration for infiltration to reach stability increases with greater rainfall. (2) An increase in rainfall intensity enhances the seismic stability of the retaining wall panel, as higher rainfall intensity results in reduced sand leakage from the panel, thereby diminishing panel deformation during vibration. (3) Increased rainfall intensity decreases the shear strength of the soil, leading to a greater load on the reinforcement. (4) The natural vibration frequencies of the three groups of retaining walls decreased by 0.21%, 0.54%, and 2.326%, respectively, indicating some internal damage within the retaining walls, although the degree of damage was not severe. Additionally, the peak displacement of the panel increased by 0.91 mm, 0.63 mm, and 0.61 mm, respectively. (5) The amplification effect of rainfall on internal soil acceleration is diminished, with this weakening effect becoming more pronounced as rainfall intensity increases. These research findings can provide a valuable reference for multi-disaster risk assessments of modular reinforced soil retaining walls.

Rammed earth, a commonly used building material in ancient times, differs from natural sedimentary layers in that it is more compact. Buildings constructed from historical rammed earth sites frequently encounter the issue of rainwater erosion. Microbially induced calcium carbonate precipitation (MICP) is commonly applied to sand soil treatment, yet reports on its use for stabilizing rammed earth are scarce. This study focused on the rammed earth of the Shanhaiguan Great Wall and explored the efficacy of MICP in mitigating rain erosion through permeation tests, splash experiments, and scouring trials. The findings indicate that the forms of rain erosion damage under MICP treatment vary across different operational conditions. In laboratory experiments, as the concentration of the cementation solution increases, the amount of calcium carbonate crystals also increases. However, the permeability, splash resistance, and rain erosion resistance initially increase and then decrease. When the cementation solution concentration is 1.0 mol/L, the penetration rate is the highest, lasting 712.55 s. The splash pit rate is the lowest, at only 1.2 mm, and the soil erosion rate is the lowest, at only 4.13%. The rain erosion resistance in the field test exhibit the same trend, and the optimal concentration is 1.2 mol/L. The optimal concentration mechanism involves the aggregation of calcium carbonate crystals at suitable cementation solution concentrations, which begin to fill the soil particle pores, effectively resisting rainwater erosion. At lower concentrations of the cementation solution, calcium carbonate crystals are merely adsorbed by soil particles without blocking the pores. Due to the high compressibility of rammed earth, which results in lower porosity, a higher concentration of the cementation solution leads to rapid pore clogging by excessive calcium carbonate crystals, which accumulate on the surface to form a white crust layer. The MICP technique can effectively alleviate rainwater erosion in rammed earth, and the optimal concentration needs to be tailored to the porosity of the rammed earth. This mechanism was also validated in field scouring experiments on the Shanhaiguan Great Wall's rammed earth.

Stronger soil layer within a layered slope is of no concern as the stronger soil layer provides extra stability. But if the relatively stronger soil layer has less permeability, it will cause hindrance to the natural infiltration processes and makes the slope vulnerable. This paper presents the results of a series of laboratory tests and numerical analyses on 45 degrees inclined homogeneous and non-homogeneous unsaturated sandy slopes subjected to continuous rainfall. The non-homogeneous slopes consist of less permeable but stronger silty-sand (NH) layers located at different locations of an otherwise homogeneous sandy soil slope. It is observed that the inclusions of NH layers within the homogeneous sandy slopes trigger a failure during continuous rainfall. The NH layers prevent the seepage of the infiltrated rainwater through the slope. As a result, the water content increases rapidly just above the NH layers and consequently the suction pressures in the soil and its shear strength just above the NH layers decrease. With the rainfall duration, the positive pore water pressures buildup just above the NH layers. This induces a slope failure with the failure plane passing above the NH layer. A discontinuity of the shear plane is also observed in the case of a multiple NH layered soil slope.

Rainwater is susceptible to pollutants such as sulphur dioxide, nitrogen oxides, heavy metals, and particles, posing challenges to water quality protection and soil degradation, impacting ecosystems and agriculture. The study focuses on the effectiveness of combined ozonation and photocatalysis in improving physicochemical parameters and reducing toxic substances. Integrated analyses, including ecotoxicological assessments, evaluate the impact of treatment on actual rainwater samples. The results indicate significant reductions in color, heavy metals, and organic pollutants after treatment. Microbiological analyses reveal the inactivation of E. coli, which is crucial for safe water reuse. Ecotoxicity studies show no toxicity to crustaceans, but slight toxicity to algae and bioluminescence bacteria in post-treatment samples. Genotoxicity assessments indicate that there is no detectable DNA damage. Overall, the study highlights the complex nature of rainwater pollution and the efficacy of photocatalytic ozonation in reducing contaminants, underscoring the need for more research to ensure sustainable water resource management.

The climate change is significantly changing the hydro-thermal state of active layer at Qinghai-Tibet Plateau (QTP), which endangers permafrost environment. The degradation of permafrost would damage the linear engineering in cold regions; furthermore, the alternation of soil hydro-thermal state in the area of rugged terrain would lead to geo-hazards and then threaten the safety of local people. Global warming is widely accepted as a big threat to the ecological environment of arctic, subarctic and alpine regions, while the changing trend of precipitation around the world is still in dispute. Furthermore, the role of precipitation accompanied with global warming is unknown. Hence, in this study, the localized monitoring data from Beiluhe permafrost monitoring station at QTP, including atmospheric and soil hydro-thermal data, were utilized for further processing and comparative analysis. Firstly, the changing trend of precipitation here was investigated through the atmospheric data from 2003 to 2013. Thereafter, the hydro-thermal change of active layer was analyzed combined with precipitation events during this period. However, the raining pattern in QTP is characterized with continuity, short duration and small amount, basically referring to thawed season. The hydro-thermal change affected by corresponding raining event could be influenced by temporally nearby event in timescale. To differentiate the effect, the characteristic precipitation event (CPE) was selected through an elaborate algorithm. Subsequently, the hydro-thermal changes of active layer were reanalyzed in response to CPEs. Representative outcomes were chosen for the specific analysis under the influence from CPEs. Hence, under the circumstance of global warming, the effect from precipitation on the hydro-thermal properties of active layer was also obtained, and the possible harmful consequence induced by that was also discussed.