Typical tunnel diseases, such as lining cracking, void behind the lining, and lining insufficient thickness, can commonly occur in tunnel structure, seriously threatening the safety state of tunnel operation. In this research, to investigate the relationship between these diseases, the cracking behavior of tunnel structure with typical combined diseases of void behind the lining and lining insufficient thickness were concentrated on using the cohesive zone model (CZM) method. At first, the zero-thickness cohesive elements were inserted between the lining solid elements globally to determine the possible cracking zone, guaranteeing the randomness of cracking. Subsequently, the characteristics of crack propagation of linings with typical combined tunnel diseases were explored detailed under the applied gradual loading. Finally, to quantitatively explore the development of lining cracks, the statistics of cracks (including the number of damaged cohesive elements and crack area) were conducted. The main results of this study indicated that the distribution of void and lining insufficient thickness influences the cracking behavior obviously, and the cracking degree shows a positive relationship with the applied gradual loading. Furthermore, as the gradual loading increases, the number of damaged cohesive elements presents a significant increasing trend, and the number of damaged cohesive elements also shows a positive relationship with the void range. In addition, the crack area also shows a positive relationship with the applied gradual loading and the void range.

1. Introduction

Cracking of lining support structure is common in tunnels, which is prone to cause engineering disasters such as concrete spalling, and collapse, seriously threatening the safe operation of tunnel structure [1-5]. In addition, typical diseases such as void behind the lining and insufficient lining thickness can also appear in tunnel structures [6-7]. The existence of tunnel typical diseases will affect the cracking performance of linings to a certain extent [8]. Therefore, it is significant to make clear the cracking behavior of linings with typical tunnel diseases.

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