软土地区土压力不对称围护结构设计分析

Analysis on retaining structure design with asymmetric earth pressure in soft soil area

在滨海软土地区进行不对称土压力地铁深基坑设计时,应考虑土压力不对称对围护结构的影响。本文参考已有支护工程经验,并结合位移对土压力的影响规律,分析3种不对称情况下的围护结构受力变形特征。结果表明:采用墙(桩)+内支撑受力体系围护结构,通过主动土压力较小一侧变形减小、较大一侧变形增大来达到受力体系平衡,从而导致围护结构实际受力、变形及地表沉降比二维计算结构偏大。在地铁基坑设计过程中,应选用最不利钻孔并考虑支护结构变形协调再平衡因素进行围护结构设计,严格控制主动土压力较大一侧位移,评估基坑可能产生的较大变形对周边环境的影响并加强监测。本研究结论可为后续类似工程提供一定的参考与借鉴。

The influence of asymmetric earth pressure on retaining structure should be considered in the design of deep subway foundation pit in coastal soft soil area.Referring to the existing support engineering experience,and combined with the influence law of displacement on earth pressure,the stress and deformation characteristics of three kinds of asymmetric retaining structures are analyzed.The results show that:the retaining structure with wall(pile)+internal support can achieve the balance of the stress system by reducing the deformation on the smaller side of the active earth pressure and increasing the deformation on the larger side,which leads to the actual stress,deformation and surface settlement of the retaining structure larger than the two-dimensional calculation structure.In the design process of subway foundation pit,the most unfavorable drill hole should be selected,and the deformation coordination and rebalancing factors of supporting structure should be considered to design the retaining structure.The displacement of the side with larger active earth pressure should be strictly controlled,and the influence of larger deformation of foundation pit on the surrounding environment should be evaluated and the monitoring should be strengthened.The research conclusions can provide references for similar projects in the future.