基于两阶段法半解析解的地铁既有线变形分析

Deformation analysis of existing metro lines based on semi analytical solution of two-stage method

针对基坑与既有线长距离并行工况,提出计算既有线变形的理论计算方法,包括基于Mindlin解的两阶段法和基于两阶段法的半解析解。通过Mindlin解可计算基坑开挖过程中在既有线位置产生的附加应力与附加位移,结合Winkler地基模型计算得到既有线变形的解析解,进而得到基坑与既有线长距离并行情况下的既有线变形值。基于传统两阶段计算方法,采用MIDAS GTS数值模拟计算附加应力对既有线结构的影响替代基于Winkler地基模型的理论计算过程,并将Mindlin位移解与之建立相关性系数关系,从而得到基于两阶段法的半解析解。最后通过对整个工况进行数值模拟验证半解析解的合理性,表明该方法是可行并有效的。该方法可以为计算基坑开挖临近既有建构筑物变形问题提供新途径。

Aiming at the long distance parallel condition of foundation pit and existing line,the theoretical calculation method of existing line deformation is put forward,including the two-stage method based on Mindlin solution and the semi-analytical solution based on two-stage method.The Mindlin solution can be used to calculate the additional stress and displacement generated at the position of the existing cable in the process of foundation pit excavation.The analytical solution of the deformation of the existing cable can be obtained by combining with the Winkler foundation model,and then the deformation value of the existing cable can be obtained when the foundation pit and the existing cable run in parallel for a long distance.Based on the traditional two-stage calculation method,MIDAS GTS numerical simulation was used to calculate the influence of additional stress on the existing structure instead of the theoretical calculation process based on the Winkler foundation model,and the Mindlin displacement solution was established with the correlation coefficient,so as to obtain the semi-analytical solution based on the two-stage method.Finally,the rationality of the semi-analytical solution is verified by numerical simulation of the whole working condition,which shows that the method is feasible and effective.This method can provide a new way to calculate the deformation of existing structures near the excavation of foundation pit.