黄土地层雨水管道施工对既有下卧地铁变形的影响

为探究基坑开挖和顶管施工共同作用下下卧隧道结构的响应规律,以西安兴善寺东街雨水管道工程为背景,采用数值模拟和实测数据分析相结合的方法对比分析采用明挖法和顶管法两种不同施工方式施工时下卧隧道变形规律,利用正交试验法研究基坑开挖和顶管施工共同作用时下卧隧道隆起量影响因素。结果表明：下卧隧道沿纵向5倍基坑开挖宽度内结构的隆起变形受基坑开挖影响较大,且基坑开挖卸荷使下卧隧道结构发生不均匀变形。左隧道拱顶最大隆起量为4.13 mm,拱腰最大收敛值约为0.55 mm,结构易发生扭转变形;右隧道拱顶最大隆起量约为3.19 mm,拱腰最大收敛值约为0.24 mm,结构易发生竖向拉伸变形。采用顶管法施工可以减少下卧隧道的变形量,实测数据表明顶管施工会使下卧隧道产生横向收敛,最大为1.7 mm,实际工程中应注意控制既有隧道结构的横向变形。基坑开挖和顶管施工共同作用时,各因素对左右隧道的影响程度不同,左隧道的隆起量主要受基坑开挖卸荷作用影响,右隧道的隆起量主要受顶管施工的顶推作用和开挖卸荷作用影响。同时应注意各因素之间不一定是相互独立的,需要考虑因素组合对下卧隧道隆起量的影响。

The effect of the construction of rain pipe in loess formation on the deformation of existing downwelling subway

To explore the response law of the underlying tunnel structure under the combined action of foundation pit excavation and pipe jacking construction, relying on a rainwater pipeline project in Xi"an, the deformation law of underlying subway tunnel under two different construction methods of open cut method and pipe jacking method are compared and analyzed by means of numerical simulation and measured data analysis. The orthogonal experiment method is used to study the factors affecting the uplift of underlying subway tunnel under the joint action of foundation pit excavation and pipe jacking construction. The results show that the uplift deformation of the underlying tunnel along the longitudinal 5 times the width of the foundation pit is greatly affected by the excavation unloading of the foundation pit, and the excavation unloading of the foundation pit causes the uneven deformation of the underlying tunnel structure. The maximum uplift of the left tunnel vault is 4.131 mm, and the maximum convergence value of the arch waist is about 0.55mm, the left tunnel structure is prone to torsion. The maximum uplift of the right tunnel vault is about 3.193 mm, and the maximum convergence value of the arch waist is about 0.24 mm, the right tunnel is prone to vertical tensile deformation. The pipe jacking method can reduce the deformation of the underlying tunnel. The measured data show that the pipe jacking method will make the underlying subway tunnel produce greater lateral convergence, the maximum is 1.7mm, and attention should be paid to control the convergence in the actual project. When foundation pit excavation and pipe jacking work together, the influence degree of each factor on the left and right tunnels is different. The uplift of the left tunnel is mainly affected by foundation pit excavation unloading, while the uplift of the right tunnel is mainly affected by the jacking and excavation unloading. At the same time, it should be noted that each factor is not necessarily independent of each other, and the influence of factor combination on the uplift of the underlying tunnel should be considered.