瞬态入渗下圆台形基坑主动土压力的滑移线解答

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中图分类号：0313；TU432 文献标志码：A 文章编号：1000-4939（2025）06-1418-11

Abstract：Inorder to characterize the distribution law of active earth pressure with depth for a circular platform foundation pit under transient infiltrations，this study derived the slip line equation for the active earth pressure of circular platform foundation pits.The derivation was based on the strength equation of generalized efective stress for unsaturated soils and matric suction under transient infiltration conditions. Subsequently，the diffrential iterative method wasadopted to obtain the slip line solution of active earth pressure for circular platform foundation pits under transient infiltrations.Last，the accuracy of the obtained slip line solution was verified，and an influencing factor analysis was conducted.The results indicate that the obtained slip line solution，compared with the existing solutions，can reasonably account for comprehensive influences of transient infiltration（time，infiltration ratio，nonlinear profiles of suction stress），soil types （sand，silt，clay），foundation pit model parameters （wall dip angle，wall-soil friction angle），and the circumferential stress coeficient on the active earth pressure of foundation pits.The accuracy of the obtained slip line solution of active earth pressure under specific reduced conditions is demonstrated by comparing it with the slip line solution of circular platform foundation pits in saturated soils （when suction stress is zero），and the limit equilibrium solution of plane retaining wals under transient infiltrations （when the radius of foundation pit tends to infinity）reported in the literature.The influence of time and infiltration ratio on the value and distribution of active earth pressure is most pronounced for foundation pits in clay，followed by foundation pits insilt.However，it is negligible for foundation pits insand，which is caused by nonlinear profiles of suction stress for different soils.The active earth pressure of foundation pits decreases significantly with the increase of walldip angle，wall-soil friction angle and circumferential stress coefficient，while its distribution and change with depth are closely related to soil types.

Key Words： transient infiltration；circular platform foundation pit；active earth pressure；the slip line method；the circumferential stress coeficient

圆台形基坑由于良好的受力特性、便捷的施工修建和显著的经济效益等优势，广泛出现在重大交通枢纽、超高层建筑和城市地下空间等建设中[1]主动土压力是圆台形基坑挡墙设计所依据的主要荷载，确定主动土压力的大小及分布具有重要的理论意义和应用价值。（剩余11475字）