ABSTRACT:

Blast tunneling and shield tunneling methods are often employed with small intervals when the auxiliary lines approaching to a subway station. The tunnel cross sections formed by blasting are often extensive and various. When shield tunnel is being constructed, the impact of the two tunneling engineering is significant. A three dimensional numerical model is establishes to simulate the construction process of certain tunnel construction by using of the finite difference program FLAC3D. The influence of tunnel construction on wall rock is analyzed, and the laws on how the post-constructed tunnel affects the displacement and stress distribution of the former constructed one are elaborated. The conclusive remarks can be a reference of the tunnel construction and other similar engineering projects.

1 INTRODUCTION

In the practice of construction of auxiliary lines near the subway station, the methods of blast tunneling and shield tunneling are often adopted within a narrow area. And the blasting tunnel in this kind of project, with extensive and various cross sections, is often close to shield tunnels. Therefore, attention must be paid when the design and construct this kind of project are performed, by considering the interactive influence of the two constructions, which implies bigger risks (Liang 2007, Jiang et al 2011, Qiu 2011). At present, the researches of tunneling with small intervals in highway or railway constructions have achieved quite many fruits and experience (Bao 2011, Li 2013, Wei & Pang 2014). However, for a specific engineering, each tunnel has its own specificity in the process of construction due to the features of the project itself, such as the distance between the tunnels, the differences between cross sections, as well as the concerned geological conditions, the construction methods, etc. In this paper, FLAC3D finite differential program is employed and a three-dimensional model is established to calculate the displacement and the changes of stress state for a certain tunnel project. By analyzing its stability, some useful conclusions are reached.

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