考虑孔隙比和渗透系数随土体当前应力变化的深基坑降水开挖变形分析
Deformation of deep foundation pits due to excavation and dewatering considering the change of void ratio and permeability coefficient with current stress of soil

基于修正剑桥模型理论，推导了孔隙比e随土体当前应力变化的方程，同时比选了4组经典的描述渗透系数k随孔隙比变化的方程，选择了其中一组最佳的估算公式，编写ABAQUS用户子程序VOIDRI和USDFLD，以实现孔隙比和渗透系数随土体当前应力的变化。在此基础上，研究深基坑降水开挖所致的坑内外土体的变形、围护结构的变形及弯矩，得到以下结论：当考虑孔隙比随土体当前应力变化时，坑外地表沉降量、墙体的水平位移、地下连续墙的弯矩、坑底隆起量均大于孔隙比为定值时的情况；当考虑渗透系数随土体当前应力变化时，坑外地表沉降量、墙体的水平位移、地下连续墙的弯矩均小于渗透系数为定值时的情况，但同时考虑渗透系数和孔隙比变化情况时，其对坑底的隆起量的影响可以忽略不计。
The function of void radio e changing with current stress was derived using the theory of Modified Cam-Clay Model. Simultaneously，four groups of classic estimate formula about permeability coefficient changing with void radio were compared to identify the accurate one. User subroutines VOIDRI and USDFLD in ABAQUS were compiled to realize the variation of void radio and permeability coefficient along with the change of current stress of soil. Then the soil displacement，the deformation and the bending moment of retaining structure caused by excavation and dewatering with or without considering the change of void ratio and permeability coefficient with current stress of soil were compared. The results showed that i with changing void ratio,values of ground settlement horizontal displacement of diaphragm wall， bending moment of diaphragm wall and rebound at bottom were larger than those with constant void radio. When permeability coefficient changed with current stress of soil，values of ground settlement，horizontal displacement and bending moment of diaphragm wall were smaller than those with constant permeability coefficient however，the change of void radio and the permeability coefficient with the current stress has no significant impact on soil rebound at bottom.