Structural Response of the Metro Tunnel under Local Dynamic Water Environment in Loess Strata

Junling Qiu,Guanglong Zhang,Ke Wang,Yiwen Qin,Jinxing Lai,Hao Wang,Fangyuan Niu

doi:10.1155/2019/8541959

Abstract

The reasons, prevention, and control of loess disaster are of great concern in practice. In recent years, Xi’an city, China, has taken the leadership in large-scale construction of subway lines in the loess strata. To study the structural response of the tunnel in loess region under local hydrodynamic environment, an experimental testing in 1g as well as a numerical simulation were performed, in which the achieved results were verified and were found to be in good agreement. Furthermore, the results showed that when the water outlet point is above the lining, the overall stress of the lining is “peanut shell,” as the water pressure of the outlet point decreases, the tensile stress of the top and bottom of the lining increases, while the compressive stress on both sides decreases; the channel form of the flow to the lining changes with the variation of the position of the water outlet point. It is worth mentioning that in the process of water gushing, the closer to the water source, the greater surface subsidence is, and there is a positive correlation between water pressure and surface subsidence. This study is of significant benchmark for the construction, maintenance, and prevention of tunnel in loess strata under the influence of water environment.

Highlights

In the 1840s, Lyell studied sediment deposits along the Mississippi River in the middle of the United States and initially proposed the academic term “Loess” [1]
The leakage of urban pipelines will lead to large-scale collapsibility of loess strata
Based on the water gushing disaster of a section tunnel on Xi’an Metro Line 4, the structural response and damage evolution of the tunnel in loess region under local hydrodynamic environment are systematically studied by model test and numerical simulation

Summary

Introduction

In the 1840s, Lyell studied sediment deposits along the Mississippi River in the middle of the United States and initially proposed the academic term “Loess” [1]. In the past 10 years, Xi’an city, as a main developing city in Western China, has taken the leadership in large-scale construction of subway in the loess strata [14, 15]. There are lots of ground fissures in Xi’an, so the disturbance of tunnel construction will inevitably lead to large strata deformation [23–27]. The leakage of urban pipelines will lead to large-scale collapsibility of loess strata. On the one hand, scholars in related fields took soak infiltration as the main condition of the experiment and analyzed the mechanism of the catastrophe of subway tunnel project in the groundwater depression cone area and the effect of leakage range of pipeline on the deformation

Objectives

Results

Conclusion