考虑基坑支护结构变形模式的土压力研究

为了减小经典朗肯土压力理论与工程中实际土压力的误差,在经典朗肯土压力理论的基础上,减少了其基本假定中的限定性条件,考虑基坑支护结构变形产生的土拱效应以及基坑支护结构与土体间的摩擦力,通过分析平面应变条件下土单元体的极限平衡状态,提出了修正的朗肯土压力理论。用理论分析结合实例验证的方法与经典朗肯土压力理论做对比,发现修正的朗肯主动土压力大于经典朗肯主动土压力,修正的朗肯被动土压力小于经典朗肯被动土压力。同时还讨论了不同基坑支护结构变形模式对极限状态下土压力分布的影响,最后分析了极限状态下修正的朗肯土压力对黏聚力与内摩擦角两个参数的敏感性。

Research on Earth Pressure Considering Deformation Pattern of Foundation Pit Supporting Structure

In order to reduce the error between Classical Rankine’s earth pressure theory and the real earth pressure in engineering, based on the classical Rankine’s earth pressure theory, the authors reduced the limiting condition in its assumptions to take soil arch effect due to foundation pit supporting structure deformation and the friction between foundation pit supporting structure and soil into consideration. Then a modified Rankine’s earth pressure was suggested through the analysis of soil element limit equilibrium under plane strain state. Compared with the classical Rankine’s earth pressure through theoretical analysis and example verification:the modified Rankine’s active earth pressure is larger than that of classical Rankine theory, and on the contrary, the modified Rankine’s passive earth pressure is smaller than that of classical Rankine’s theory. The influences of different deformation patterns of foundation pit supporting structure on the distribution of earth pressure were also discussed. Finally, the sensitivity of the modified Rankine’s soil pressure to the two parameters of cohesive force and internal friction angle was analyzed.