岩基上挡土墙抗倾覆稳定分析的讨论

Exploration of Analysis on Stability Against Overturning of Retaining wall on Rock Foundation

对岩基上挡土墙抗倾覆稳定分析进行讨论,指出传统分析方法存在各种问题的主要原因是因其假定前提不合理。从分析单一安全系数通式中的结构抗力和作用效应出发,认为对于抗倾覆稳定分析,结构抗力是地基反力对基底截面重心的最大稳定力矩,作用效应是荷载对结构基底的偏心矩。假定地基反力的竖向分力不变,作用点移至基底前缘,可得到地基反力能提供的最大稳定力矩,据此可推导出岩基上抗倾覆稳定系数K0的新计算公式。在传统公式取稳定力矩为全部竖向荷载对墙趾的力矩之和、倾覆力矩为全部水平荷载对墙趾的力矩之和的情况下,竖向合力作用于基底重心外侧时,传统公式算出的安全系数将大于新公式;竖向合力作用于基底重心内侧时,传统公式算出的安全系数将小于新公式;竖向合力作用于基底重心时,传统公式算出的安全系数等于新公式。

Analysis on stability against overturning of retaining wall on rock foundation is explored. Main reasons for various issues in the canventional analyzing method are from the unreasonable assuming conditions. From analysis on the structural resistance and action effect in the general formula for the safety factor, it considers that, in the analysis against overturning, the structural resistance is the principal stabilizing moment of the foundation reaction to the base section barycenter and the action effect is the eccentricity of load to the structural base. Assuming that the vertical component of the foundation reaction is constant and the acting point is shifted to the front edge of the base, the maximum stabilizing moment provided by the foundation reaction can be obtained. From this, the new formula for factor K0 of stability against overturning of the strncture on rock foundation is derived. When the stabilizing moment is the sum of the whole vertical loads to the wall toe and the overturning moment is the sum of the whole horizontal loads to the wall toe in the conventional formula, and when the vertical resultant acts outside the base barycenter, the safety factor by the conventional formula is greater than that by the new formula; when the vertical resultant acts inside the base barycenter, the safety factor by the conventional formula is smaller than that by the new formula; when the vertical resultant acts at the base barycenter, the safety factor by the conventional formula is equal to that by the new formula.