圆砾地层深大基坑施工降水设计及应用研究

在深大基坑施工过程中，地下水是影响深大基坑稳定性较为关键的因素，若处理不当极易引发深大基坑施工安全事故。目前，富水地质的大型基坑工程的降水设计及工艺要求严格，应用较少，因此需进行深入研究。依托昆明轨道交通4号线火车北站深大基坑的工程实例，结合车站周边水文地质特征，设计坑内降水井降水、坑外布置备用井的降水方案，并采用VisualModflow数值模拟软件对基坑降水方案进行模拟验算。计算结果表明：该降水方案能够满足基坑降水要求，同时基坑降水引起周边地表沉降在允许安全范围以内。同时，经现场监测数据进一步验证，火车北站基坑开挖期间，地下水位变化较为稳定，周边地表沉降符合规范要求。该降水方案对类似深大基坑降水设计具有借鉴指导意义。

Dewatering Design and Application of Deep and Large Foundation Pit Construction in Gravel Stratum

In the construction process of deep and large foundation pits, groundwater is the key factor that affects the stability of deep and large foundation pits. If it is not handled properly, it is easy to cause safety accidents in the construction of deep and large foundation pits. At present, the dewatering design and technology of large-scale foundation pit engineering in water- rich geology are strict, and the application is less, so it is necessary to carry out in-depth research. Based on the engineering example of the deep foundation pit of Kunming Rail Transit Railway North Station, combined with the hydrogeological characteristics around the station, this paper designs the dewatering scheme of dewatering wells in the pit and arranging standby wells outside the pit. The dewatering scheme of the foundation pit is calculated and simulated by VisualModflow numerical simulation software. The calculation results show that the dewatering scheme can meet the requirements of foundation pit dewatering, and the surrounding surface subsidence caused by foundation pit dewatering is within the allowable safe range. At the same time, it is further verified by the on-site monitoring data that during the excavation of the foundation pit of the North Railway Station, the change of groundwater level is relatively stable, and the surrounding surface settlement meets the requirements of the code. The dewatering scheme has reference and guiding significance for the dewatering design of similar deep and large foundation pits.