Study On Crack Characteristics And Prevention Of Lining Structure Of Mountain Tunnel

Tunnel lining structural cracking is the most common tunnel structural disease,and it is also a disease that the tunnel avoid happening from design to completion.Based on the disease detection data of the Jinyunshan Tunnel of the Chengdu-Chongqing Expressway and the Bayue Mountain Tunnel of the Yurong Expressway,this paper studies the main causes of the cracking of the tunnel lining structure.The concrete fracture mechanics theory combined with the extended finite element method is used to analyze the cracking characteristics of tunnel lining structure under typical incentives.Based on the latest specifications and engineering actual conditions,the prevention and control measures of the cracking of the lining structure of the mountain tunnel are proposed.The main work and achievements of the thesis are as follows:1.Based on the mountain tunnel cracking disease detection project,the main contents and methods of the lining structure cracking disease detection are introduced.Through the inductive statistics of the detection data of the lining structure of several mountain tunnels,the main causes of the damage of the lining structure of the mountain tunnel and the manifestation of the disease are studied.The influence of cracking disease on the operation safety of the tunnel is analyzed.The main factors that cause the cracking disease of the tunnel lining structure are the voids behind the lining structure,the surrounding rock bias,the relaxation load and the temperature difference shrinkage stress.2.The law of cracking and damaging of lining structure under the main cause of the tunnel is studied.Modeling analysis of lining structure cracking is carried out by two typical causes of voids behind the lining due to construction defects and biasing loads on the tunnel lining.The mechanism of cracking disease of tunnel lining structure,the performance characteristics of lining cracking,the location of cracked cracks,crack width and depth expansion law are studied.It is found that the failure mode of the lining structure under the typical incentive is mainly the tensile crack penetration,and the stress concentration area will appear near the crack.The degree of damage of the lining structure is different to the bearing capacity of the lining structure.3.The safety evaluation method of tunnel lining structure cracking disease at home and abroad is introduced.Based on the variation of the degree of cracking and the bearing capacity of the lining structure,a safety evaluation method for the lining structure based on the crack depth of the lining structure is proposed.4.This paper introduces the prevention principles and governance principles of tunnel lining structure cracking diseases at home and abroad,and analyzes the causes of lining structure cracking diseases from the aspects of structural design,construction technology and geological environment change in the context of structural disease control engineering.On this basis,the prevention and control measures for the cracking disease of the lining structure of the mountain tunnel are proposed.