Experimental investigation of the effect of train load on mechanical properties of rock

Serious inverted arch structural problems have been observed in some heavy-haul railway tunnels. To identify the causes of these structural issues, a series of compression tests were conducted to investigate the effect of train load on the mechanical properties of surrounding rock. Numerical analysis of the dynamic response of the tunnel to the heavy-haul train load was performed to obtain the frequency and amplitude of dynamic stress in the rock. Then the dynamic stress was applied to the sandy shale rock in the compression tests. The test results showed that after applying 300,000 cycles of train load, the elastic modulus and peak strength of the rock remained nearly constant. This indicates that the degradation of the surrounding rock due to train load is not a primary factor in the invert arch structural problems observed during the initial stage of heavy-haul railway operation.