矩形槽开挖失稳滑动体形状及整体稳定分析

利用矩形槽段开挖引起周围地基土体应力变化和变形的解析解答,分析了不同长宽比槽段开挖引起的主应力变化,得到滑动体的形状近似为半椭圆体,在水平面上其长轴长度约为短轴长度的2倍,短轴长度约为槽段长宽比的0.44倍.同时将槽壁的整体稳定安全系数定义为土体抗剪强度与实际动用剪应力的比值,针对浅槽、深槽和平面应变情况下的半椭圆滑动体进行极限平衡分析,尝试提出了一种用于评价槽壁整体稳定性的分析方法,并通过该方法的实际应用结果初步验证了半椭圆滑动体假设的合理性.

Sliding wedge shape and analysis method of global stability of rectangular excavated trenches

By using an analytical solution for calculating the stress changes and displacements around an excavated rectangular diaphragm wall panel trench,the principal stress changes around trenches of various aspect ratios were analyzed and a semi-ellipsoidal sliding wedge was derived.On the horizontal plane,the length of the major axis of the semi-ellipse is about twice the length of its minor axis,and the latter is about 0.44 times of the trench's aspect ratio.Meanwhile the factor of safety of the global stability of the trench is defined as the ratio of soil shear strength to its mobilized shear stress.Based on the limit equilibrium analysis of the semi-ellipsoidal sliding wedge for shallow trenches,deep trenches and plane strain trenches,an analytical method is proposed to evaluate the global stability of the panel trenches.In addition,the rationality of the assumed semi-ellipsoidal sliding wedge is tentatively verified by practical applications of the proposed method.