Study on the disaster mechanism and treatment measures of invert uplift cracking of in-service tunnel - A case research

Tunnel structure diseases occurred frequently during service period, which seriously threatened the operation safe of trains. Aiming at the above problem, this paper combined with the case of inverted arch uplift disease treatment of an in-service tunnel in Shanghai-Kunming high-speed railway, and based on the disease characteristics investigation and causes analysis, a disease treatment scheme was proposed as: Removing the old invert to the non-destructive rock layer -* Taking bedrock grouting reinforcement -* Reconstruction the inverted arch for deeper and standardize the construction. The scheme was verified and used to guide the construction. The analysis results showed that the contact stress (compressive stress) between bedrock and invert distributed symmetrically, the value increased gradually with time and finally tended to be stable. The stress peak values in three monitoring sections were 168.58, 171.26 and 166.55 kPa, respectively. The uplift deformation of bedrock and invert also experienced rapid accumulation at first and then gradually stabilized. The deformation stability values of rock at three monitoring sections reached 3.99, 3.64 and 3.89 mm respectively, and the uplift deformation value of invert were 1.35, 1.19 and 1.23 mm respectively. Both the contact stress and the deformation value all indicated that the measures of bedrock grouting and reconstruction inverted arch in deeper can effectively control the stress and deformation of surrounding rock and inverted arch structure, ensuring the tunnel structure stability and train operation safety. The research results have great theoretical reference significance and engineering practical value for the treatment and prevention of existing tunnel structural diseases.