考虑渗流应力耦合作用的深基坑开挖变形研究
Excavation deformation of the deep foundation pit in the perspective of coupling seepage-stress effects
云南民族大学学报:自然科学版,2017,26(1):89-94

汪慧莲 WHL

摘要


基于土体渗流应力耦合效应及本构理论,针对某场地地下水埋深较浅、粉质黏土和粘土分布较厚的深基坑工程建立了相应开挖支护三维有限元模型.通过室内试验测定了基坑土体的修正剑桥本构关系参数并将修正剑桥本构关系应用于基坑开挖支护的数值模拟分析中.分别研究了基坑开挖过程中有无渗流-应力耦合效应的基坑整体变形、支护结构位移、坑外地表沉降及坑底回弹情况.研究结果表明:①含水粉质黏土和粘土采用修正剑桥本构关系较合适;②考虑渗流应力耦合作用时基坑支护结构水平位移、坑外地表沉降及坑底回弹量分别是未考虑渗流应力耦合作用时的0.57倍、0.07倍、0.59倍,基坑开挖变形应充分考虑渗流应力耦合作用;③坑底超前降水能显著减小坑底隆起. The three-dimensional finite element model of one selected deep foundation pit excavation was built based on the seepage-stress coupling effects and constitutive theory of soil. Thick silty clay and clay are distributed in the foundation pit where the groundwater level is higher. The modified Cam-clay model parameters of the foundation soil were determined by the laboratory test, and the modified Cam-clay model was applied to the numerical simulation analysis of the excavation support of this foundation pit. The deformation of the foundation pit, the horizontal displacements of the supporting structure, the ground settlement, and the excavation rebound are researched respectively during the excavation of the deep foundation pit coupling with the effect of seepage-stress or not. The results go as follows: (1) It is suitable to use the modified Cam-clay model for watery silty clay and clay. (2) When the coupling effect of the seepage-stress interaction during the foundation pit excavation is taken into account, the horizontal displacements of the supporting structure, the ground settlement and the excavation rebound of the foundation pit are 0.57 times, 0.07 times and 0.59 times respectively compared with the situation of ignoring the coupling effect of the seepage-stress interaction during the excavation of the foundation pit. The coupling effect of the seepage-stress interaction should be fully considered during the analysis of the excavation deformation of the foundation pit. (3) Precipitation at the bottom of the pit in advance can reduce the excavation rebound significantly.

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