复杂地层深基坑井群降水综合控制方案优化分析

为控制工程物料成本及时间成本的投入，实现对复杂地层降水控制措施的合理化选择。以京安城际榆安1号隧道明挖段深基坑降水施工为背景，通过有限元模型分析和现场抽水试验相结合的方法，研究了止水帷幕插入深度、单井抽水速率及抽水时间对深基坑降水效果的影响。结果表明：基坑降水止水帷幕插入比控制在1:0.9时，基坑降水效率及成本投入最优；抽水时间随单井抽水速率整体呈先快慢的下降趋势，但增加到一定范围后趋势变缓、相关性减弱，单井最优抽水速率取125 m3 /d最优；抽水1~7天坑内地下水位降幅较大，达到最大降深的95.2 %，以第7d的水位降深为标准进行降水方案设计最合理。可见科学的降水方案不仅有助于水资源保护也关系到工程降水安全经济进行。

Optimization Analysis of Comprehensive Control Plan for Dewatering of Deep Foundation Pit Wells in Complex Strata

In order to control the input of engineering material and time, the rational selection of precipitation control measures in complex formations is realized. Based on the precipitation construction of deep foundation pit in the cut-and-cover section of the Jing''an intercity Yu''an No. 1 tunnel, the effects of finite element model analysis and on-site pumping test were used to study the effects of waterstop curtain insertion depth, single well pumping rate and pumping time on the precipitation effect of deep foundation pit.The results show that when the insertion ratio of water stop curtain is controlled at 1:0.9, the dewatering efficiency and cost input of foundation pit are optimal. The pumping time decreases rapidly and slowly with the pumping rate of a single well, but the trend becomes slow and the correlation weakens when it increases to a certain range. The optimal pumping rate of a single well is 125 m3 /d. From 1 to 7 days after pumping, the lower water level of sinkhole decreased greatly, reaching 95.2% of the maximum depth, and the precipitation scheme design was the most reasonable based on the water level depth reduction on the 7th day. It can be seen that scientific precipitation plan is not only helpful to water resources protection but also related to the safety and economic progress of project precipitation.