考虑邻近地下结构影响的基坑变形三维数值分析

3D Numerical Analysis of Deep Excavation Considering the Effect of Adjacent Substructures

基于摩尔库伦弹塑性本构,提出了考虑土体小应变刚度特征的数值分析方法,并在有限差分软件FLAC3D中实现二次开发.将提出的数值方法用于模拟某基坑的施工过程,该基坑邻近既有地铁车站,且坑内外分别存在横墙和立柱桩.将数值计算结果与实测数据进行对比,验证所提出的数值方法的有效性.进一步对比分析了有无立柱桩和坑内横墙时围护墙的变形特性.研究表明,由于基坑与车站间的土体宽度大于临界宽度值,其围护墙变形不受邻近车站地下结构的影响;立柱桩的存在能够减小主动区土压力,坑内横墙增加了被动区的抗力,使得围护墙变形明显减小.

Based on the Mohr-Coulomb（MC）elastoplastic constitutive model,this paper proposes a numerical method,which considers the small strain stiffness of soil.The proposed method is developed in the finite difference software,FLAC3D,and is used to model the construction process of a deep excavation in Shanghai.The excavation is adjacent to a metro station with cross walls and column piles located inside and outside the excavation respectively.The proposed numerical method is validated by comparing the numerical results with the field data.Moreover,the effect of the cross walls and column piles on the deformation behavior of diaphragm walls is illustrated.The results show that the metro station has no effect on the deformation of the retaining wall because the width of the confined soil between the excavation and metro station is larger than the critical width.Column piles can decrease the active earth soil pressure due to the arching effect while the cross walls can increase the resistance in the passive zone,which decreases the deformation of the retaining walls.