Model test and numerical simulation on the invert heave behaviour of high-speed railway tunnels with rainstorm

Abstract

Extreme weather with torrential rainstorms has brought a new challenge to the operation of railway tunnels in karst areas. Especially for high-speed railway (HSR) tunnels, the uplift of the invert structure caused by the high external water pressure (EWP) seriously affects the normal operation of the HSR line. This paper presented a series of 3D printing model tests to investigate the occurrence mechanism and evolution law of invert heave disease after rainstorm and drainage blockage. Numerical simulations were used to study the mechanical response of the tunnel structure under different groundwater levels and drainage blockage degrees. The results show that the uplift displacement of the invert increases with the EWP. The maximum EWP occurs at the invert whether the drainage system is blocked or not, which is the main factor leading to such disease. Drainage blockages increase the severity of the disease. Especially with blockages exceeding 50%, the EWP on the invert and the corresponding uplift displacement increase significantly. Furthermore, groundwater levels and drainage blockages will both cause increased stresses in the tunnel bottom structure, leading to problems such as excessive uplift displacement and cracking. Some useful suggestions for tunnel construction and operation were obtained from the results.