| Abstrakt: |
In the western and southwestern regions of China, under-construction and completed highspeed railway tunnels often suffer from elevated floor heave, which seriously threatens the construction progress and operational safety of the tunnels. This paper relies on the typical horizontally laminated carbonaceous shale stratum of the Xingshandong Tunnel to carry out a research on the mechanism of elevation of the base of the back arch. The model of the surrounding rock below the base of the elevated arch is simplified by applying the method of qualitative analysis by component testing and quantitative calculation by numerical simulation. The effects of different layer thicknesses, interlayer cohesion and material strength on the damage pattern of laminated rock masses are revealed, the causes of bottom bulging in horizontally laminated rock enclosures are analysed and corresponding bottom bulge control and disposal techniques are proposed. The results indicate: (1) The reduction in layer thickness reduces the ability of the laminated composite rock mass to resist deformation and damage, mainly manifested in the shortening of the elastic phase and the acceleration of the deformation rate; the reduction in the bond strength between layers destroys the integrity of the laminated composite rock mass, leading to the acceleration of the laminated rock mass into the single rock layer stress phase, but the effect on the deterioration of ultimate bearing capacity is not obvious;the reduction in the strength of the rock mass itself greatly reduces the load-bearing capacity of the laminated composite rock formation, causing the damage process to accelerate significantly and further deepening the extent and scope of the impact, which, combined with the numerical simulation results, further proves that the strength of the rock mass itself dominates the deformation and damage of the laminated rock mass. (3) The fatigue damage of train vibration, the weakening effect of groundwater aggregation and the long-term mechanical properties of the surrounding rock will all affect the stability of the elevation arch of the tunnel, and the order of deformation control effect is: deepening invert>base grouting>invert arch bolt. [ABSTRACT FROM AUTHOR] |
