复杂平面基坑支护结构失稳原因与加固技术

The Cause of Instability and Reinforcing Measures of Retaining System for Complicated Planar Foundation Pit

衡阳某大型商城基坑平面形状复杂,支护结构采用桩锚体系。在基坑开挖后出现了支护结构顶部水平位移监测结果超过了报警值且持续增加的情况,施工在没有进行深入分析的基础上采用了增加预应力锚杆和局部反压的措施,没有有效控制支护结构的水平位移,支护结构出现失稳现象。文章介绍了该基坑基本情况以及水平位移监测成果,着重分析了失稳发生的机理,考虑周边环境的变化采用弹性支点法对支护结构进行了复核计算,在此基础上提出了卸载、砖墙填土反压等加固措施,取得了良好效果。

A Pile-anchor is applied as the support system for the foundation pit of a large-scale commercial building in HengYang. After excavation, the horizontal displacement monitoring results show that the pile＇ s top deformation of retaining structure exceeds the warning value and continue increase in the process of excavation. The prestressed anchor bolt and earth berm were added in local area without deep consideration and the displacement was not controlled effectively and the retaining structure is in a dangerous state. This paper introduces the foundation pit and horizontal displacement monitoring results, stresses on analysis of mechanism for instability and a check is carried out on retaining structure by elastic subgrade method in view of changes in surroundings around foundation pit. This paper presents some reinforcing measure based on analysis ,for example ,unloading and brick masonry wall with earth berm, and good effect has been gained.