软土深基坑工程支护结构设计m值与弯矩反分析

Back-analysis of m value and bending moment of supporting structure design parameters for deep excavation engineering in soft soil

基于实际软土深基坑工程,依据施工各工况实测位移,分别采用单纯形法位移反分析对基坑支护结构设计参数m值和光顺样条法拟合对地下连续墙弯矩进行分析,并判定设计值和预测值之间的相互关系,为设计和施工提供一定的理论依据。根据单纯形法反演得到优化位移与实测位移基本接近,验证了反分析方法的可靠性,对设计参数m值可取其下限来控制基坑的最大变形。根据光顺样条法拟合求得曲率的基础上分别按弹性刚度和短期刚度进行弯矩估算,可得地下连续墙最大弯矩变化规律基本一致,且在基坑开挖初期,地下连续墙弯矩可以通过弹性刚度法估算墙体的弯矩承载力,随着基坑的开挖,地下连续墙弯矩实际更接近于规范短期刚度计算值。

Based on the practical deep foundation pit engineering of softsoil and the measured dispracement of construction condition,simplex method for displacement back analysis of foundation pit retaining structure disign paramener m （supporting structure design parameter）was analyzed.The smothing spline fifting method of under ground continuous wall bending moment were also studied.The design value and the mutual relation ship be-tween the predicted values were used to provide certain theoretical basis for the design and construction.Accord-ing to the simplex method,the optimal displacement and the measured displacement are obtained,and that veri-fies the reliability of the inverse analysis method.Besides,the m value of the design parameters can be used to control the maximum deformation of the foundation pit.According to the smoothing spline fitting method which was used to obtain the curvature based respectively according to the elastic stiffness and short -term stiffness of bending moment estimation,underground continuous wall maximum bending moment changes are basically the same.In the early foundation pit excavation,the underground continuous wall bending moment can be used through the elastic stiffness method to estimate wall bending moment capacity.With the excavation of foundation pit,underground continuous wall bending moments is closer to the regulate short -term stiffness calculation val-ue.