软土地基基坑开挖对邻近管线影响分析

Influence of pit excavation on nearby pipeline in soft ground

横琴岛排洪渠基坑两侧较近距离范围内分布着先期建成的地下管廊结构。设计拟采用LXK工法支护基坑,由于地层条件较差,需要论证基坑开挖对地下管线的影响。利用三维有限元软件FLAC3D详细分析了基坑开挖过程中基坑围护结构和邻近地下管廊的内力和变形,结果表明基坑开挖影响范围较大,位移超过2 cm区域达到基坑外侧25 m左右,锚杆打设在基坑壁附近,加固约束土体,土体整体抗滑效果明显,而由于其结构特性限制,其在限制相邻结构的整体侧向位移方面效果并不理想,且加长锚杆至邻近结构,对限制基坑开挖引起的相邻结构侧向位移效果有限,分析结果可为相关施工及设计提供指导。

There are built underground pipelines near the trench in Hengqin island and the LXK method is used for the supporting structure. Considering the poor geological condition, the influence of pit excavation on the pipeline should be evaluated. Three-dimensional FE software called FLAC3 D is used to analyze the stress and deformation of the supporting structure and pipeline during the excavation. The results show that the influence range during the pit excavation is relatively large and there is still over 2 cm displacement at the distance of 25 cm. The bolt can strengthen the restraint soil near the foundation pit wall, the overall anti-sliding effect of the soil is obvious. Duo to the limitation of its structural characteristics, its effect on limiting the overall lateral displacement of adjacent structures is not ideal. And increasing length of bolts to the adjacent structure has limited effect on the lateral displacement of adjacent structures caused by the restriction of excavation.The analysis results can provide guidance for related adjacent construction and design.