长春市某建筑基坑支护结构事故原因的分析

Analysis on the accident cause of certain retaining structure for building foundation excavation in Changchun

长春市某12m深基坑采用排桩锚杆支护结构,因土压力分析有误,支护结构设计不合理,导致基坑大部分开挖到基底后,排桩结构水平位移超过允许范围,桩间土大面积掉落,基坑外地面出现地裂缝,由槽钢组成的腰梁扭曲变形,桩顶冠梁向基坑内变形明显,并出现裂缝。由于施工单位及时采取回填反压措施,才控制住支护结构的变形。然后,通过进一步的理论分析,并对原支护结构增加一排锚杆后,基坑开挖才得以顺利进行。

The soldier pile anchors for certain retaining structure of the deep foundation pit with the depth of 12m in Changchun were adopted. Because of the incorrect analysis on the earth pressure and the unreasonable design of the retaining structure, while the excavation reached the bottom of the foundation pit, the horizontal displacement exceeded the allowed range for the soldier pile structure, the large area of soil between the piles fell down, the cracks appeared on the surface out of the foundation pit, the middle beam composed of U-steel deformed, the deformation of the beam at the top of the pile caps facing to the foundation pit was obvious, and the cracks appeared. Because the effective measure with the backfill pressure was timely adopted the deformation of the structure was controlled. After the farther theoretical analysis and the increase of a row of the anchor to the structure, the excavation of the foundation pit could be carried on smoothly.