软土地区超深基坑设计优化分析

Optimization and Analysis of Ultra-Deep Foundation Pit Design in Soft Soil Area

天津一中心医院新址基坑工程位于天津西青软土区,具有超大、超深的特点.开挖后由于工期因素,需要对原支护方案进行优化调整,采用启明星软件和Plaxis 2D有限元模拟对优化前后的典型剖面进行对比,并将开挖实测数据与模拟值进行综合对比分析.结果表明:在支护桩已经完成的条件下,优化后方案技术可行,安全可靠,支护桩的弯矩和截面变化处于合理范围内.同时,在北侧和西南角设立两座出土栈桥,有利于提高开挖效率,缩短工期,降低成本,部分区域支护桩最大侧向水平位移地表沉降值比原方案有所增加,变形依旧控制在合理范围内,可对类似的超大深基坑工程方案优化提供借鉴.

The foundation pit of the new site of Tianjin NO.1 Central Hospital is located in Xiqing soft soil area of Tianjin and the pit is extremely large and deep.Due to the construction period after excavation,the original support scheme needs to be optimized and adjusted.QiMingXing software and Plaxis 2D finite element simulation are used to compare the typical sections before and after optimization,and the measured excavation data and simulated values are comprehensively analyzed.The results show that:under the condition of supporting pile being completed,the optimized scheme is technically feasible,safe and reliable,and the bending moment and section change of the supporting pile are within a reasonable range.Two unearthed piers are added in the north and southwest at the same time,increasing the efficiency of excavation.Construction period has been shortened and the cost has been greatly lowered down;parts of supporting pile maximum lateral horizontal displacement of the surface subsidence value have also been increased compared to the original plan.The deformation is still controlled within a reasonable range,and it can be used as reference for optimization of similar extra-large deep foundation pit engineering schemes.