基于静力触探对深基坑突涌区地层扰动的分析

Piping Potential and Strata Disturbance Evaluation in the Deep Excavation Using Cone Penetration Test

在深基坑开挖过程中,承压水对基坑安全的威胁是需要重点关注的因素之一。依托南京江北新区某深基坑承压水突涌事故,结合基坑突涌后实际情况从原位测试的角度入手,采用静力触探的方法对基坑突涌事故后地层扰动的范围和程度进行分析。基坑突涌前、后静力触探结果与实际情况相比表明:管涌点周边(4)2a粉细砂夹粉土的力学性质与坑外侧严重区基本接近;静力触探测试结果与实际情况相符;采用静力触探来分析突涌后地层扰动问题的方法可行;可为深基坑承压水导致的基坑突涌事故的治理提供一定的借鉴,对国内类似工程突涌区地层扰动的治理、控制进行初步探索。

The safety hazards induced by the artesian groundwater beneath the soil strata is one of the factors that posting safety hazards in the deep excavations.The case history of a piping accident occurred in a deep excavation project in Jiangbei New District in Nanjing City is presented in this paper.The vertical and horizontal limits of the piping disturbed zone were evaluated through the Cone Penetration Test(CPT).The CPT test result comparisons before and after the accident can have the following conclusions:the mechanical properties of the(4)2asilty fine sand lens with silty soil around the piping points are close to that of worst soil area outside the excavated area.The CPT results are consistent with the failed conditions;It is feasible to use the CPT test to analyze the stratigraphic disturbance zone after the piping;which provides some reference for the remediation of the excavation piping hazards induced by the artesian groundwater below the excavation zone.