渗流作用对泥炭质土基坑结构力学与变形行为的影响

Effect of Seepage on Mechanics and Deformation Behavior of Peaty Soil Foundation Pit Structure

依托昆明市某泥炭质土基坑工程,分析渗流作用对开挖过程中泥炭质土基坑结构力学与变形响应的影响。借助数值软件Geo Studio建立了泥炭质土基坑结构二维数值模型,对SIGMA/W模块和SEEP/W模块进行了耦合,以研究渗流-应力耦合作用下基坑结构力学与变形特征;分析了止水帷幕长度对基坑结构渗流场的影响;对比了考虑与不考虑渗流作用时排桩弯矩、排桩侧向变形和基坑内外竖向变形的差异。研究结果表明:增加止水帷幕长度可延长渗流路径,继而改变基坑结构力学与变形响应;每步开挖后前3 d渗流速度的降幅达70.9%以上;与不考虑渗流作用相比,考虑渗流作用时基坑外地表沉降与排桩侧向变形更大,且基坑变形的影响范围更广,对周围环境的威胁更大。

Based on a peaty soil foundation pit project in Kunming,the effect of seepage on the mechanical and de-formation response of the peaty soil foundation pit was studied during excavation.A 2D numerical model was estab-lished by Geo Studio software.The SIGMA/W module and SEEP/W module was coupled to study the mechanical and deformation characteristics of the foundation pit structure under the coupling effect of seepage and stress;The effect of the length of waterproof curtain on the seepage field of the pit structure was analyzed.The differences in the bend-ing moment and lateral deformation of pile rows,and vertical deformation inside and outside the pit were compared with and without seepage effect.The results show that increasing the length of the waterproof curtain can prolong the seepage path,and then change the mechanical and deformation response of the foundation pit structure;After each step of excavation,the seepage velocity is reduced by more than 70.9%in the first 3 d;Compared with no seepage effect,the surface settlement outside the pit and lateral deformation of the pile rows are greater than those with seepage effect.And the influence range of foundation pit deformation is wider,as well as the threat to the surround-ing environment.