Elastoplastic Analysis of Ellipsoidal Hole Expansion in Unsaturated Loess
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摘要: 在非饱和土统一强度准则中引入非饱和原状黄土黏聚力与基质吸力拟合公式,采用改变孔型系数k的方法并结合边界条件、平衡方程及应力协调方程,推导了排水与不排水条件下椭球形扩孔在ξ平面内的弹性区与塑性区应力-应变场、塑性区半径及极限扩孔压力的解析解,并利用MATLAB软件分析了基质吸力、强度准则和剪胀对解析解的影响.结果表明:不同排水条件下非饱和黄土有效应力均随孔型系数k及基质吸力的增大而增大;当参数r/rp一定时,在排水条件下,有效应变随剪胀系数h及基质吸力的增大而增大,且后者的影响程度更大;在同等条件下,b=1时双剪应力强度准则下的有效应力-应变均大于b=0时的Mohr-Coulomb强度准则.Abstract: In the unified strength criterion for unsaturated soils, the formulae of cohesion of unsaturated undisturbed loess and matrix suction were introduced. The method of changing hole pattern coefficient k was combined with boundary conditions, equilibrium equations and stress compatibility equations to derive stress and strain solutions under drainage and undrained conditions. Analytical solutions of the stress and strain fields, the plastic zone radii and the limit hole expansion pressure in the elastic and plastic regions around the ellipsoid hole in the plane, and the influences of the matrix suction, the strength criterion and the dilatancy on the analytical solutions were discussed with the MATLAB software. The results show that, the effective stresses of unsaturated loess under different drainage conditions will increase with hole pattern coefficient k and the matrix suction; when the parameters are constant, the effective strain under the drainage condition will increase with dilatation coefficient h and even more with the matrix suction; with the same condition, the effective stress and strain under the double shear stress strength criterion for b=1 will be larger than those under the MC strength criterion for b=0.
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