Numerical Analysis on Interaction Between Closely Spaced Shield Tunnels

Abstract

This paper presents a three-dimensional numerical model simulating a small-spacing overlapped shield tunnel driving course. Using this model, the influences of shield tunnel construction parameters on ground settlement, and existing shield tunnel axis floating are studied. The driving process of the shield will bring inevitable impacts upon the surrounding stratum and the existing tunnel. Therefore, the determination of construction parameters of shield tunnel, including support pressure in the face, decrease of soil modulus caused by shield machine, grouting pressure and properties of lining grouting slurry is a big problem. The Hardening soil (HS) model as it is implemented in the finite element code PLAXIS 3D, is used to simulate construction parameters and tunneling construction process. It is shown based on the analysis of construction parameters that when construction parameters were controlled reasonably, the ground settlement and deformation of existing tunnel lining induced by shield tunnel construction can be decreased effectively. The first tunnel construction produced disturbance on surrounding soil making the following tunnel longitudinal and transverse settlement value increasing than the first hole. Influence of the following tunnel construction to the first of the hole was a process (arrival, passes through this process), which is illustrated in the transverse settlement curve, the first cave settlement increased first and then decreased.