软土地区超深基坑施工监测与分析

Monitoring and Analysis of Ultra-deep Foundation Pit Construction in Soft Soil Area

软土地区硬X射线自由电子激光装置项目的土建配套工程1号与4号工作井基坑开挖深度均超40 m,1号井、4号工作井内基坑净长×净宽分别为20.0 m×70.0 m、55.0 m×50.4 m。1号工作井的内支撑型式为对撑加斜撑,4号工作井的内支撑型式为边桁架加十字对撑。通过对1号、4号工作井基坑施工期间的支护结构变形与支撑轴力进行跟踪监测,对两种不同基坑支护型式下的支护结构受力与变形规律进行了对比分析。结果表明,在整体支撑养护时间有限的情况下,矩形基坑采用对撑加斜撑的支护效果要明显优于采用十字对撑加边桁架的支撑。

The excavation depth of No.1 and No.4 working shafts foundation pits in the civil engineering supporting works of hard X-ray free electron laser device project is over 40 m.The net length×net width of the foundation pits in the No.1 and No.4 working shaft are 20.0 m×70.0 m,55.0 m×50.4 m respectively.The inner support type of No.1 working shaft is double support and diagonal support,and the inner support type of No.4 working shaft is side truss and cross support.By tracking and monitoring the deformation and axial force of supporting structure during the construction of No.1 and No.4 working shafts,the force and deformation laws of the supporting structure under two different types of foundation pit support are comparatively analyzed.Results show that,under the condition of limited curing time for the overall support,the support effect of the rectangular foundation pit with the double support and diagonal support is evidently better than that of cross support and side truss support.