某深基坑支护结构加固设计监测实例分析

Case analysis of reinforcement design and monitor of supporting for a deep excavation

以兰州市区某深基坑工程为例,介绍了复杂环境条件下,针对基坑开挖过程中开挖深度增加及现场实测岩土参数较原设计采用的数值降低情况下所采取的支护结构加固技术措施,并对基坑监测结果进行了分析。结果表明,本工程所采取的加固措施有效地确保了支护系统和周边环境的安全,此外,发现基坑周边地表沉降和邻近建筑物沉降的发展变化与支护桩桩顶水平位移相比具有相对缓慢和滞后的特征,这一现象说明在兰州市类似土岩组合地层深基坑中采用桩锚支护体系时,桩后土体具有明显的三维拱效应。

Taking a deep excavation in Lanzhou city as an example,in view of the increase of excavation depth and the decrease of geotechnical parameters from field measurement compared with the original design under complex environment conditions,the technical measures of supporting structure reinforcement adopted are introduced.The monitoring results of excavation are analyzed.The results show that the reinforcement measures adopted in this project effectively ensure the safety of supporting system and surrounding environment.In addition,it is found that the ground settlement around the foundation pit and the settlement development of adjacent buildings are relatively slow and lag compared with the horizontal displacement of the supporting pile top.This phenomenon shows that the three-dimensional arch effect is existed obviously in the soil behind the pile when the pile-anchor supporting system is used in deep excavation of similar soil-rock combination strata in Lanzhou.