考虑松动区内应力分布形式的松动土压力研究

传统土拱效应理论是基于松动区内土体应力均匀分布这一基本假定建立的，然而由于松动区内部主应力轴偏转的影响，实际情况下松动区内部的土体应力分布往往是非均匀的。针对这一情况，在太沙基松动土压力分析模型的基础上，通过假定3种不同形状的大主应力轨迹线，考虑了松动区内应力分布形式对松动土压力的影响，对传统太沙基松动土压力公式进行了修正，并与离散元数值模拟结果进行了对比验证。研究结果表明：当土体达到极限平衡状态时，松动区内部竖向应力与水平向应力分别呈上凹式分布和上凸式分布，松动区中轴线上侧向土压力系数等于被动土压力系数；采用不同形状的大主应力轨迹线进行计算所得应力分布之间的差异在10%以内，且均与离散元数值模拟结果吻合良好，从而验证了修正解的有效性。为计算方便起见，推荐相关工程中采用圆弧形大主应力轨迹线假定进行计算。

Research on loosening earth pressure considering the patterns of stress distribution in loosening zone

Traditional theory of soil arching effect is based on the assumption of homogeneous stress distribution in loosening zone. However, because of the influence of main stress axes deflection in loosening zone, the stress distribution is inhomogeneous. Based on Terzaghi’s loosening earth pressure theory, three types of major principal stress path are assumed and then a modified analytical solution of loosening earth pressure is presented considering the influence of stress distribution. DEM is also used to compare the model. The results show that when soils arrive ultimate equilibrium state, the distributions of vertical stress and horizontal stress in loosening zone are concave and convex respectively, and lateral earth pressure coefficient equals to passive earth pressure coefficient on the axle of the loosening zone. Difference among different major principal stress paths is less than 10% and these results are all in agreement with DEM numerical results, which confirms the effectiveness of the modified analytical solution. For the convenience of calculation, it is recommended to assume an arc path of major principal stress in the calculation of relevant projects.