In order to study the influence of rainfall infiltration on the shear characteristics of sandy slopes, this paper conducted a model test of sandy slopes under rainfall to investigate the vertical and horizontal displacement variation laws of sandy slopes at different positions during the entire rainfall process under different rainfall intensifies. The results show that: The vertical displacement of the soil on the sandy slope at different positions showed a trend of increasing rapidly at first and then slowly throughout the entire rainfall process. The relationship of the magnitude of the vertical displacement of the soil at the same depth was the top of the slope > the bottom of the slope > the middle of the slope. However, the horizontal displacement of the sandy soil at each position changed significantly at different stages of rainfall. The change was obvious at the top of the slope in the early stage of rainfall, and the horizontal displacement was mainly in the middle of the slope in the middle and later stages of rainfall. According to the cloud map of the moisture content distribution of the slope after rainfall, based on the cloud map results and the force characteristics, direct shear tests of sand samples with different moisture contents were carried out. The research shows that: Under the same normal stress, the peak shear stress and peak shear displacement are negatively correlated with the change of moisture content. The increase of moisture content reduces the interlocking effect between particles. When the moisture content increases from 5 to 30
With the increasing exploitation of deep underground space, ensuring the safety of excavations in water-rich environments is necessary. Groundwater leakage through retaining structures, like diaphragm wall, poses a significant risk, yet its influence on excavation deformations is not fully understood. This study establishes a hydro-mechanical model to investigate the deformation characteristics of a deep excavation subjected to diaphragm wall leakage. The analysis simulates leakage occurring in different soil layers to evaluate its effects on wall deflections and ground settlements. The results indicate that the hydraulic properties of the soil layers of leakage location are the critical factor. Leakage in confined aquifers caused the largest increase in wall deflection (up to 30
This study presents a systematic investigation into the sensitivity of slope stability under steady seepage conditions to key soil and hydraulic parameters using a finite element-based strength reduction approach combined with a one-factor-at-a-time (OAT) methodology. A series of parametric studies were conducted, including cohesion c, friction angle θ, density ρ, permeability k, Young’s modulus E, and Poisson’s ratio ν, under varying slope angles (β = 30°, 45°, 60°) and water level differences (H = 2–10 m). The results demonstrate that cohesion exhibits a strong positive linear correlation (average slope ≈ 0.033/kPa) with the factor of safety (FOS), while water level difference shows an equally strong negative linear correlation (average slope ≈ − 0.058/m). Critically, these two effects operate independently without significant interaction. Furthermore, tan(θ) displays a more linear relationship with FOS than θ itself, and this relationship demonstrates dependence on water level difference with higher H values amplifying the sensitivity of FOS to tan(θ). In contrast, permeability and elastic parameters exhibit negligible influence on slope stability, while density shows only a minor reducing effect. The study confirms that cohesion and friction angle dominate slope stability under steady seepage, whereas permeability and elastic parameters can be considered negligible in practical applications. These findings offer valuable insights for slope design under seepage conditions, though their applicability remains limited to homogeneous soil profiles and steady seepage.
When constructing ultra-deep foundation pits in complex leaky aquifers, substantial drawdown in confined aquifers is often required to ensure pit stability. However, the leakage effect between aquifers significantly increases the difficulty of controlling groundwater outside the pit. To address this issue, this paper first introduces an ultra-deep foundation pit project in the Pudong area of Shanghai. The depth of excavation is approximately 37 m, supported by an approximately 80 m-deep diaphragm wall. Using this project as a case study, a three-dimensional hydro-mechanical coupled numerical model based on the HSS soil constitutive model was established. This model simulated the entire excavation process, capturing data on drawdown in confined aquifers, lateral displacement of the retaining structures, and ground settlement. The results were then compared and validated against field monitoring data. The results indicate that the 3D hydro-mechanical coupling analysis method based on the HSS (HS-Small) constitutive model can effectively simulate the environmental deformations induced by ultra-deep foundation pit construction.
The current stability calculation methods for stiffened pressure steel pipes do not fully account for the influence of initial geometric imperfections on buckling capacity, and their calculation procedures are relatively complicated. In this study, finite element models of stiffened pressure steel pipes with varying radii, stiffener ring spacings, and wall thicknesses were established. Linear perturbation analysis was employed to obtain buckling modes and critical eigenvalues. The first-order buckling mode was then introduced into the original model as an initial geometric imperfection with different amplitudes, and the nonlinear arc-length method was further applied to analyze the decay characteristics of buckling loads. Based on extensive finite element simulations, an empirical prediction formula for buckling loads was developed, with stiffener spacing, pipe geometry, and imperfection amplitude as variables. When the imperfection amplitude was set to 5
