基于辛体系的筋箍碎石桩受力变形分析

Stress and deformation analysis of geosynthetic-encased stone columns based on symplectic system

因土工格栅套筒的环箍效应,筋箍碎石桩的受力变形机理较普通碎石桩更为复杂。将筋箍碎石桩单桩的受力变形视为空间轴对称问题,基于辛体系理论构建了可考虑桩体横截面剪应力的辛对偶方程,并对方程进行变量分离,再结合边界条件得到了筋箍碎石桩沉降及径向变形的辛体系解答。通过算例分析验证了方法的合理性与可行性。进一步的参数分析表明:筋箍碎石桩的沉降及鼓胀变形随筋材抗拉刚度的增大而减小;随桩土应力比的增大而增大,但增长率逐渐减小;随加筋深度的增大而减小,但超过最优加筋深度时不再变化;而最优加筋深度则随荷载的增大、桩间距的增大及侧压力系数的减小而相应增大。

Due to the hoop effect of geogrids,the stress and deformation mechanism of geosynthetic-encased stone columns(GESCs)is more complex than that of the ordinary stone columns.In this study,the stress and deformation of a single GESC is regarded as a space axisymmetric problem.Based on the symplectic system theory,a symplectic dual equation considering the shear stress of the cross section of the column is formulated,the variables of the equation are separated,and the distribution functions for the settlement and radial deformation of GESCs are finally obtained according to the boundary conditions.The rationality and feasibility of this method are verified by the practical example,and the parameter analysis shows that the settlement and bulging of GESCs decrease with the increase of encasement stiffness.They increase with the increase of pile-soil stress ratio,but the growth rate decreases gradually.They decrease with the increase of encasement depth,but no longer change when they exceed the optimal encasement depth.The optimal encasement depth increases with the increase of load and pile spacing,and with the decrease of lateral pressure coefficient.