Deep excavations in silt strata can lead to large deformation problems, posing risks to both the excavation and adjacent structures. This study combines field monitoring with numerical simulation to investigate the underlying mechanisms and key aspects associated with large deformation problems induced by deep excavation in silt strata in Shenzhen, China. The monitoring results reveal that, due to the weak property and creep effect of the silt strata, the maximum wall deflection in the first excavated (Section 1) exceeds its controlled value at more than 93% of measurement points, reaching a peak value of 137.46 mm. Notably, the deformation exhibits prolonged development characteristics, with the diaphragm wall deflections contributing to 39% of the overall deformation magnitude during the construction of the base slab. Subsequently, numerical simulations are carried out to analyze and assess the primary factors influencing excavation-induced deformations, following the observation of large deformations. The simulations indicate that the low strength of the silt soil is a pivotal factor that results in significant deformations. Furthermore, the flexural stiffness of the diaphragm walls exerts a notable influence on the development of deformations. To address these concerns, an optimization study of potential treatment measures was performed during the subsequent excavation of Section 2. The combined treatment approach, which comprises the reinforcement of the silt layer within the excavation and the increase in the thickness of the diaphragm walls, has been demonstrated to offer an economically superior solution for the handling of thick silt strata. This approach has the effect of reducing the lateral wall displacement by 83.1% and the ground settlement by 70.8%, thereby ensuring the safe construction of the deep excavation. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Mining causes damage to the soil and rock mass, while rainfall has a pivotal impact on the mining slope stability, even leading to geological hazards such as landslides. Therefore, the study evaluated the mine landslide stability and determined the effectiveness of the treatment measures under the impact of pore water pressure changes caused by rainfall, taking the Kong Mountain landslide in Nanjing, Jiangsu Province, China, as the research object. The geological conditions and deformation characteristics were clarified, and the failure mechanism and influencing factors were analyzed. Also, the landslide stability was comprehensively evaluated and calculated utilizing the finite element-improved limit equilibrium method and FLAC 3D 6.0, which simulated the distribution of pore water pressure, displacement, etc., to analyze the influence of rainfall conditions and reinforcement effects. The results indicated the following: (1) Rainfall is the key influencing factor of the landslide stability, which caused the pore water pressure changes and the loosening of the soil due to the strong permeability; (2) The distribution of the pore water pressure and plastic zone showed that, during the rainfall process, a large area of transient saturation zone appeared at the leading edge, affecting the stability of the whole landslide and led to the further deformation; (3) After the application of treatment measures (anti-sliding piles and anchor cables), the landslide stability increased under both natural and rainfall conditions (from 1.02 and 0.94 to 1.38 and 1.31, respectively), along with a reduction in displacement, plastic zones, etc. The Kong Mountain landslide, with the implemented treatment measures, is in good stability, which is in line with the evaluation and calculation results. The study provides certain contributions to the stability evaluation and treatment selection of similar engineering under rainfall infiltration.

A great concern for the construction surface cracks of large cross- tunnels, which are being or to be built in the loess strata of China, is attracted. The mechanism of surface crack formation is analyzed from both internal and external perspectives. Loess is a multi-phase porous medium and develops complex stress and strain variation while executing a tunnel project. The surface is highly susceptible to construction surface cracks in shallow sections. A statistical analysis of the constructed loess tunnels in China shows that the main factors affecting surface cracks are settlement deformation, construction scheme, and the surrounding soil environment. To gain an in-depth knowledge of the mechanism of action of factors influencing surface cracks in loess tunnel construction, we relied on the actual project engineering to conduct numerical simulations, which can reproduce the formation mechanism of surface cracks more intuitively. Through numerical simulation, the influence mechanism of tunnel surface cracks under different tunnel diameters, tunnel depths, excavation methods, and surrounding soil grades was obtained. Through the analysis of the factors affecting surface cracks, specific measures to prevent and deal with construction surface cracks are further optimized to provide new ideas for the selection of surface crack control routes in loess tunnels.