某基坑锚杆失效事故的原因分析

针对沿海软土地区一大型基坑中深达810 m的冷冻机房基础在基坑开挖过程中发生锚杆失效基坑坍塌事故，从挖土深度考虑不足、不良地质作用、锚杆施工间距超过设计要求、卸土放坡范围不足、锚杆抗拔承载力取值过高等5个方面进行了事故原因分析和模拟工况单元内力计算比较，指出了5大原因综合作用下增加的锚杆拉力设计值大大超过锚杆抗拔承载力而引发锚杆失效，基坑失稳破坏。

Analysis on the Causes of Anchor Bolt Failure Accident in a Foundation Pit

In the process of the foundation pit excavation of a freezing room with 8.10 meters depth,which is in a large foundation pit in coastal soft soil area,collapse caused by anchor bolt failure occurred.By the analysis and calculation com-parisons of simulation working conditions element internal force in 5 aspects: insufficient consideration of digging depth,bad geological environment,bolt spacing exceeding the design requirements,insufficient range of step-slope by soil dump-ing and taking higher value of anchor pullout capacity,it was concluded that the increased anchor tension design value greatly exceeded the anchor anti-pulling force capacity by the comprehensive influence of above 5 aspects,which led the an-chor bolt failure and the instability of foundation pit.