淤泥质黏土层中盾构区间上方基坑开挖施工

The Excavation of Foundation Pit Above Shield Section in Silty Clay Layer

杭州南站东广场基坑开挖时,部分基坑位于地铁5号线已成型的盾构区间上方,盾构区间顶覆土16.32m,位于3-2淤泥质黏土层中,东广场基坑深8m。由于卸荷比约为1.63,基坑开挖对盾构区间影响较大。论文分析了三轴搅拌桩加固土体、分层分块对称开挖等措施进行盾构区间的保护。实践表明:选择的三轴搅拌桩加固工艺及拟定的开挖措施能有效控制隧道变形。

During the excavation of the foundation pit of east square of Hangzhou south railway station,part of the foundation pit was located above the formed shield section of subway line 5.The top of the shield section was 16.32m,and it was located in 3-2 muddy clay layer.The foundation pit of east square was 8m deep.Since the unloading ratio is about 1.63,the excavation of foundation pit has a great influence on the shield section.This paper analyzes the measures of soil reinforcement by triaxial stirring pile and symmetrical excavation by stratification and partition to protect the shield section.The practice shows that the selected technology and the proposed excavation measures can effectively control the tunnel deformation.