Research on the effects of the excavation of cross passage for the displacement of tunnel and the surface of earth

Abstract

In the construction of urban subway, the excavation of the cross passage is usually carried out after the completion of the main tunnel. At the same time, it is necessary to ensure the safety of the cross passage itself and the stability of the main tunnel and the normal access of the ground is also indispensable. Therefore, it is of great significance for the whole project to accurately grasp the scope of influence and the rule of change of the construction of cross passage. Based on the cross passage of subway in Xuzhou, the influence of the excavation of cross passage on vertical, horizontal displacement of tunnel and the settlement of ground is studied through the finite element software called MIDAS GTS/NX. The following conclusions are drawn:the curve of the settlement of the upper part of the tube, the uplift of the lower segment and the convergence of tunnel caused by the excavation of the cross passage are “U”, half pentagonal, and triangular and the influence of tunnel with hole side is obviously greater than that of the other side tunnel. Besides, the overall range of impact is within 30m of the longitudinal distance from the central line of the tunnel. The tunnel eventually moves upwards and it moves toward the direction of the cross passage. The settlement curve of the change of surface caused by excavation of cross passage is basically the shape of “U”. The main influence area is 15m within the center line of cross passage and the settlement of the soil near the middle line of the connecting passage is the most obvious, 6.5mm. In addition, all values meet the requirements of the deformation of control, which confirms the effect of the reinforcement of grouting.