基于主应力轴旋转理论的修正Terzaghi松动土压力

基于土体主应力轴旋转理论,提出了Trapdoor上方土体侧向土压力系数的一般表达式,从而修正了传统的Terzaghi松动土压力计算公式。对于无黏性土,该系数是一个只与土体有效内摩擦角相关的参数,其值介于1.0和被动土压力系数Kp之间,且随着有效内摩擦角的增大而增大。黏性土的侧向土压力系数则与Trapdoor上覆土体厚度、重度、有效黏聚力和有效内摩擦角及Trapdoor宽度等参数有关。与传统计算方法相比,修正后的Terzaghi松动土压力计算结果与国内外Trapdoor模型试验结果及FLAC数值分析结果更为吻合,可广泛应用于地下管道、地基局部沉陷及隧道工程的土拱应力分析。

Modified Terzaghi loozening earth pressure based on theory of main stress axes rotation

Based on the theory of main stress axes rotation, the analytical expression of the lateral earth pressure coefficient of the soil overlying on the Trapdoor is presented; and the traditional Terzaghi loosening earth pressure is modified. For the cohesionless soil, the coefficient is only related to the effective internal friction angle of soil; and its value varies from 1.0 to the passive earth pressure coefficient Kp. It increases with the increase of the effective internal friction angle of the soil. For the cohesive soil, the modified Terzaghi loosening earth pressure is influenced by the thickness, unit weight, effective cohesion and the effective internal friction angle of the overlying soil on the Trapdoor as well as the trapdoor width. Compared with the traditional expressions, the proposed one of the Terzaghi loosening earth pressure is more in agreement with the experimental ones and FLAC numerical results. It can be used to analyze the soil-arching effect in the engineering of underground pipe, local subsidence of ground, tunnel and so on.