Study on the influence of surrounding rock to the tunnel excavation by numerical simulation

The long tunnel of Yuanliang mountain which is buried in a deep depth is the dominate project of Huaiyu line. The span of tunnel is 11068 meter. The terrain condition and geologic condition is very complex. The demolish technique is used widely in the digging of tunnel in order to quicken construction schedule. However, the earthquake effect produced by frequent demolish exercise will bring serious influence to nearby soluble cavity and terrane, induce the cranny of terrane, and water will gush the tunnel. Based on the demolish condition in excavating on Yuanliang mountain tunnel, study were made on a typical numerical simulation by DYNA2D which was exploited by J.O. Hallquist in Lawrence Livermore National Laboratory (LLNL). During the numerical simulation, analysis on stress field and velocity field appearing wall rock in soluble rock stratum were made. Sine the program applies finite element method to calculate big distortion dynamic respond of nonlinear constructional material, adopt of node unite to discrimination, calculation on symmetry and plane strain problem could of carried out; it employs simple point Gauss integral, introduce sandglass glutinosity to control zero energy mode, and apply central difference to find way into time integral; The meet-bounce of program can dispose aperture and slide in march with surface of material, also can provide with multifarious material model and state equation; The program is provided with mesh subdivision function, when meshes distort severely and mesh need to be partitioned over again so that the computer can proceed steadily, all unite and node variable can be transformed to new grid system by means of interactive mode. At the repartition backwards and forwards, the parameter of internal energy, kinetic energy and momentum etc can be calculated. Especially, the program can manage dynamic response of high-speed impact and high explosive blasting and the transformation of temperature field in structure, which make the program is especially adopted to demolish numerical analog computation.