复杂深基坑二次开挖支护结构设计与监测分析

Design and Monitoring Analysis of Secondary Excavation Support Structure for Complex Deep Foundation Excavation

采用Midas GTS对二次开挖未加固的基坑开挖过程进行有限元模拟,通过对基坑破坏特征的深入分析,提出了基坑二次开挖的支护方案,并对不同方案模型做了数值模拟,结果表明桩前预留土台对基坑控制变形有较好的效果。考虑到土台自身变形较大、原桩施工质量及土台稳定性问题,最终选定土台前新增支护桩并采用连梁与原支护桩相连的方案;同时对基坑工程开挖进行了现场监测,并对监测数据进行了处理分析,结果表明支护桩及坡顶的变形在安全范围内,提出的加固方案科学可靠。

The Midas GTS was used to simulate the excavation of the foundation excavation without secondary excavation,and based on the deep analysis of the characteristics of foundation excavation failure,the support scheme of secondary excavation of foundation excavation was put forward,and the numerical simulation of different scheme models showed that the pre-pile soil table had good effect on the deformation control of foundation excavation.Taking the large deformation of the soil table into account,the construction quality of the original pile and the stability of the soil table,the final selection of the new support pile before the pile and the use of the beam and the original support pile connected to the program.At the same time,the site excavation of the foundation excavation was monitored and the monitoring data were analyzed.The results showed that the deformation of the supporting pile and the roof was within the safe range,and the proposed reinforcement scheme was scientific and reliable.