地震荷载下土体应力分析与挡土墙土压力计算分析

Stress Analysis of Soil Mass and Calculation of Retaining Wall Pressure under Seismic Load

地震荷载作用下,按现有规范采用拟静力法设计的挡土墙仍发生了各种破坏。为探索地震荷载下土中应力分布对于岩土抗震工程的作用,合理地进行挡土墙抗震设计,采用拟静力法对地震荷载进行描述,根据弹性力学理论并假设问题满足平面应变的条件下,推导地震荷载下土体主应力的大小和方向的计算公式。通过对该点Mohr应力圆的分析,给出挡土墙动土压力大小与土体裂缝深度计算方法。研究结论:(1)地震主动和被动土压力系数均随着内摩擦角的增大而增大;(2)黏聚力对地震主动土压力系数的大小无影响,对地震被动土压力系数的影响较小;(3)土体裂缝深度随内摩擦角和黏聚力的增加而增大。

Under seismic load, the designed retaining wall based on quasi-static method as specified by current norms still experiences many kinds of damages. In order to probe how the stress distribution under seismic load influences the seismic resistance of geotechnical projects and to acquire the proper anti-seismic design of retaining walls, this paper uses quasi-static method to describe the seismic load and deduces the formula of the strength and the direction of earth’s principal pressure under seismic load based on the theory of elastic mechanics and the assumption that the issue meets the plane-strain condition. The analysis of the stress circle of the spot is conducted to obtain the calculation method for the strength of dynamic soil pressure and the depth of crack in the soil. The results show that ： （1） positive and negative seismic earth pressure coefficients increase while the internal friction angle increases; （2 ）cohesive strength has no effect on positive seismicearth pressure, but has smaU effect on negativeseismic earth pressure; （ 3 ） the depth of thecrack in the soil increases with the increase of the internal friction angle and the cohesive strength.