深基坑开挖对近接高速公路安全影响评估

Assessment on Impact of Deep Foundation Pit Excavation on Safety of Adjacent Expressways

摘要:

天津集疏运货运通道部分墩台深基坑紧邻在运营的长深高速，加之滨海软土地质条件，深基坑施工作业导致的既有道路开裂风险极高。为评估基坑开挖对道路安全的影响，采用有限元数值方法，分析了施工过程中支护受力、路基变形等规律。结果表明：在当前施工和支护设计方案下，路基边坡坡脚1 m范围内的土体水平变形超标，基坑开挖导致的既有道路开裂风险较高。建议适当提高承台底标高以降低基坑开挖深度，或对内支撑施加预轴力，以提高支护结构强度；同时施工过程中要加强基坑和路堤变形监测工作，合理确定路基水平变形监控限值和预警值，并做好应急预案。

Abstract:

Due to the deep foundation pits of some piers in Tianjin Freight Transportation Channel adjacent to the Changshen Expressway in operation, coupled with the coastal soft soil geological conditions, the risk of existing road cracking caused by deep foundation pit construction is very high. In order to assess the impact of foundation pit excavation on the road safety, the finite element numerical simulation method is used to analyze the laws of supporting force and roadbed deformation in the process of construction. The results show that under the current construction and supporting design scheme, the horizontal deformation of soil within 1 m of the slope foot of the roadbed side exceeds the standard, and the risk of existing road cracking caused by foundation pit excavation is higher. It is recommended to appropriately raise the elevation of the base slab bottom to reduce the depth of pit excavation, or apply the pre-axial force to the internal support to improve the strength of the supporting structure. At the same time, it is necessary to strengthen the deformation monitoring of the foundation pit and embankment in the process of construction, to reasonably determine the horizontal deformation of the roadbed to monitor the limit value and the early warning value and to make emergency plans.