邻域基坑降水引起隧道位移的计算方法研究

Study on Calculation Method of Tunnel Displacement Caused by Adjacent Foundation Pit Dewatering

深基坑降水会造成周围土体渗流场及应力场变化,引起邻域地铁隧道纵向不均匀沉降,严重影响运营地铁安全。鉴于此,提出一种邻域基坑井群降水引起既有地铁隧道纵向沉降的解析计算方法。首先,基于有效应力原理及达西定律,在考虑土体总应力变化的情况下,计算基坑群井降水在隧道位置处产生的附加应力;之后,将隧道简化为Winkler地基上的Euler-Bernoulli梁,计算隧道结构纵向轴线位移;最后,通过三维有限元数值模拟方法进行对比分析,验证了所提计算方法的准确性。成果可以为合理预测基坑降水对邻域既有隧道的影响提供一定理论依据。

The dewatering of deep foundation pit causes the change of surrounding soil seepage field and stress field,which leads to the longitudinal uneven settlement of the adjacent subway tunnel and seriously affects the safety of subway operation.In view of this,an analytical method for calculating the longitudinal settlement of existing subway tunnels caused by dewatering of adjacent foundation pit wells is proposed.Firstly,based on the effective stress principle and Darcy's law,considering the change of the total stress of the soil,the additional stress generated by the dewatering of the foundation pit group wells at the tunnel location is calculated;then,the tunnel is simplified as Euler-Bernoulli beam on Winkler foundation,and the longitudinal axis displacement of tunnel structure is calculated;finally,the accuracy of the proposed calculation method is verified by comparing and analyzing the three-dimensional finite element numerical simulation methods.The results can provide a theoretical basis for reasonably predicting the impact of foundation pit dewatering on existing tunnels in the neighborhood.