Abstract

The frame structure analysis method has been generally applied for the tunnel structure design, which was widely utilized due to its fast calculation speed and convenient modeling. In this paper, the frame analysis model was established to explore the effect of typical tunnel diseases of voids and lining insufficient thickness on the mechanical and deformation behavior of concrete linings. At first, the lining model with the diseases of void and lining insufficient thickness was established in the frame structure analysis platform. Subsequently, the lining inner force (taking the bending moment as an example) and the deformation behavior were explored. At final, the differences in the deformation behavior were investigated with different vertical loading conditions. The main results in this paper revealed that when the vertical loosening pressure can be transferred to the lining structure within the void zone, the maximum positive bending moment of the lining is located near the crown, while the maximum negative is at the shoulder, and the phenomenon of internal bending mainly occurs in the void area, and the phenomenon of external bending occurs at the shoulder. The lining has a significant downward displacement at the crown, while the deformation direction of the structure is outward at the shoulder. However, when the vertical loading cannot be transferred to the lining within the void zone, the obvious phenomenon of deformation outwards will occur within the void zone.

1. Introduction

During the operation of the tunnel structure, unsatisfactory diseases such as voids and insufficient lining thickness are common due to some adverse conditions [1-7]. The above diseases can be regarded as typical causes for many other defects [8]. Therefore, it is significant to make clear the influence of diseases such as voids and lining insufficient thickness on the tunnel structure.

Concerning the effect of voids behind the lining on the safety state of the tunnel structure, Zhang et al. [9] evaluated the effect of double voids behind the lining on the safety state of the tunnel structure. Meguid et al. [10] investigated the impact of voids on the circumferential stresses in the lining, the axial forces and bending moments were concentrated. Li et al. [11] carried out a two-dimensional finite element method (FEM) to study the distribution of inner force with voids behind the lining, and the effect of void location, as well as the void size, were discussed. Zhang et al. [12] explored the effect of void size on the lining structure, and a three-dimensional model with a single void behind the lining was further established to make clear the effect of the longitudinal length of void on the tunnel structure. Jiang et al. [13] explored the void effect on the degraded lining structure based on the two-dimensional finite difference method (FDM). Furthermore, Zhang et al. [14] investigated the effect of voids behind the lining on the progressive failure of tunnel structure, and the inner force of the lining was also studied. On the other hand, regarding the effect of lining insufficient thickness on tunnel structure. Zhang et al. [15] studied the influence of insufficient lining thickness on tunnels, the distribution of inner force was investigated. Wang et al. [16] investigated the effect of multiply insufficient lining thickness on the safety state of tunnels, and the sensitivity for the location of insufficient thickness was further explored. Wang et al. [17] experimental studied the effect of insufficient lining thickness on the mechanical behavior of the tunnel.

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