Study on failure mechanism and treatment measures of floor heave of high-speed railway tunnel in the interbedded surrounding rock with high geostress

Abstract

The tunnel floor heave is easy to occur in the interbedded surrounding rock with high geostress, which has a serious impact on the safety of the tunnel structure and the normal operation of the tunnel. Through field investigation, numerical simulation, and in-situ monitoring, this paper studies the failure mechanism and corresponding treatment measures of the floor heave of a high-speed railway tunnel from various aspects such as geostress, surrounding rock structure, and bottom structure. The results show that the high horizontal geostress, the structure of interbedded surrounding rock, and the weak inverted arch are the reasons for the tunnel floor heave failure. Under the condition that high horizontal geostress acts on the structure of interbedded surrounding rock mass, the underlying rock layer under the tunnel will undergo cyclic deformation or failure, and the tunnel will show floor heave failure. Based on the research results, treatment measures such as removal and replacement of the inverted arch, anchor cable and anchor bolt anchoring were taken to treat the foundation and overall track bed of the tunnel. After the treatment, an automated monitoring system was established to monitor the displacement of the inverted arch, surrounding rock pressure, and steel stress for three years. Based on the analysis of monitoring results, this treatment plan can effectively control the tunnel floor heave. The research results can provide reference for the prevention and control of other tunnel floor heave failures.