Study On The Effect Of Caverns Behind The Tunnel Lining Stability Under The Blasting Load

This paper relies on blasting excavation of Chongqing nanshan tunnel. Itnumerically simulates the process of blasting vibration by he collected field data ofblasting vibration and ANSYS/LS-DYNA software. It discusses about the influences ofblasting vibrating load on the safety and studies on the stress wave propagation rules,under the condition of the Caverns tunnel behind surrounding rocks, where the initialsupport has been done. The main research content and result of the paper are asfollows：1. This paper analyzes the mechanism of rock blasting and the stress wavepropagation rules. The results show that, the stress wave plays a major role in theblasting damage of hard rocks, which produces the breakage effect. While the expansivepressure of explosive gases plays a major role in the blasting damage of soft rocks.2. Theoretically research on the Caverns tunnel behind surrounding rocks. It can beregarded as double-tunnel, one of which is smaller. Its stress state can be directlyobtained by the elastic-plastic mechanics. And under the condition of double-tunnel,superimposed stress has an affect on tunnels.3. Discuss about the numerical simulation and loading method of blasting vibrationloads. This paper discuss about the three main numerical simulations and loadingmethods. The simplification of triangular load, real waves, and the state equationdescribe the relationship between pressures and specific volumes during the blastingprocess.4. The principle and key points of finite element software include introduction ofthe software, introduction of constitutive model of the rock mass, constitutive model ofexplosives, process modes of border terms, analysis of safety factors, and so on.5. Numerical simulation process. By ANSYS/LS-DYNA software, the papersimulates the influences of blasting vibrating load of the Caverns tunnel on thesupporting structures, which is in different size and location. The numerical simulationcalculation of the paper can directly guide the excavation blasting construction of thetunnels, optimize construction schemes, and reduce the damage to the tunnel support.The results show that, under the rock grade V, the emptying tunnel bellow2meterhas significant effects on the tunnel support, the positions of Caverns tunnels within a certain has significant effects on them, and the further has no significant effects onthem.