考虑固结和流变耦合作用的基坑工程时间效应

Time-effect of Excavation Considering the Coupling of Consolidation and Creep

软土地区深基坑工程具有时间效应。基坑的各项参数,比如墙体水平位移和支撑轴力等,其数值不会因开挖的停止而不再发生变化。其原因一般地是土体固结和流变等效应所引起的。本文采用MERCHANT模型来模拟土体的流变性,依据Biot固结有限元法编制了有限元分析程序。程序分别以渗透系数和粘滞系数来反映固结的快慢和流变性的强弱。通过计算温州地区饱和软粘土地基深基坑开挖工程实例,验证了程序的可信性。程序通过对参考算例的分析,分别得到了纯固结作用和流变与固结耦合作用对基坑性状影响的规律:固结有利,流变不利,耦合作用使得具体的各项参数表现复杂化。

Time effect is detectable in deep excavation in soft clay. Excavation＇s parameters, such as support forces and the lateral deformation of the support,are varying even if excavating is stopped, Generally,the reason is clay＇s consolidation and creep effect. With Merchant model stimulating the creep of clay,the finite element method coupled with Biot consolidation theory is used to research the behavior of deep excavation. There are two parameters： permeability coefficient to reveal consolidation effect and viscosity coefficient for creep effect. Analyzing a real example of deep excavation in saturated soft clay,it proves the credibility of this code. A reference example is numerated and analyzed,and some conclusions are received, such as the influence to support axis strength by pure ,consolidation effect and the influence to excavation character by coupled effect of consolidation and creep. To be concluded,consolidation is avail to excavation,but creep is not,and it will be complex when complied with each other.