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基坑周围土体实际处于非饱和状态,忽略基质吸力的饱和土挡墙抗倾覆设计不合理。基于非饱和土的平面应变抗剪强度统一解,考虑非饱和土强度的中间主应力效应和非线性,利用力矩相等推导基质吸力均匀和线性2种分布下基坑刚性挡墙的抗倾覆临界嵌固深度方程,给出工程应用步骤,并得到新提出的抗倾覆临界嵌固系数的参数影响特性。所得结果为系列化的有序解答,具有广泛的理论意义和很好的适用性。研究表明:基坑刚性挡墙抗倾覆设计的强度理论效应明显,考虑中间主应力效应可以更加发挥非饱和土体的强度潜能;基质吸力及其分布对抗倾覆临界嵌固系数具有显著影响,应合理假定基质吸力分布并采取工程措施确保其稳定存在;处理非饱和土强度非线性影响有2种方法,采用稳定较小吸力角的方法 1简单偏保守,采用分段双曲线吸力角的方法 2精确稍复杂,应正确认识高基质吸力对非饱和土强度及其结构设计的双重影响。
The soil around the foundation pit is actually in a non-saturated state. The design of anti-overturning of the saturated soil retaining wall which neglects the suction of the matrix is unreasonable. Based on the uniaxial flat shear ultimate strength of unsaturated soils and considering the effects of intermediate principal stress and non-linearity on the strength of unsaturated soils, the critical anti-overturning embankment of rigid retaining walls Solid depth equation, the engineering application steps are given, and the parameter influencing characteristics of the newly proposed anti-overtudding critical solidification coefficient are obtained. The results obtained for the series of ordered solutions, with a wide range of theoretical significance and good applicability. The results show that the strength effect of the anti-overturning design of the rigid retaining wall of the foundation pit is obvious, and the strength potential of the unsaturated soils can be more fully taken into account by the middle principal stress effect. The matrix suction and its distribution have a significant effect on the critical overturning coefficient of overturning. Assuming that the matrix suction distribution and taking engineering measures to ensure its stable existence; dealing with the nonlinear effects of unsaturated soil strength there are 2 methods, the method of using a stable smaller suction angle 1 simple partial conservative method using sub-hyperbolic suction angle method 2 accurate Slightly complicated, we should correctly understand the dual influence of high matric suction on the strength of unsaturated soil and its structural design.