Research on the joint bearing mechanism and sensitivity of surrounding rock sharing rate of buried water conveyance tunnels

In view of the structural bearing performance issues of buried water diversion tunnels, the paper conducted a series of numerical simulation study on the joint bearing mechanism of steel lining-concrete lining-surrounding rock. Based on the actual background of a power station project in the western area of China, macroscopic and mesoscopic finite element models were established by using ABAQUS software. The influence laws of multiple parameters such as rock mass category, steel lining thickness, initial gap and internal water pressure on structural stress, displacement and rock mass sharing rate were systematically analyzed then. The research results show that: (1) The initial gap has the most significant impact on the rock mass sharing rate. A slight increase in the gap will cause a sharp decline in the sharing rate. (2) Increasing the thickness of the steel liner will reduce the rock mass sharing rate, which is not conducive to fully exerting the bearing capacity of the rock mass. (3) Compared with the standard analytical method, the finite element method takes into account the force transmission effect of the concrete lining, and the calculated rock mass sharing rate is generally 3.4%–17.8% higher, which are more in line with the engineering reality.