SURROUNDING ROCK DEFORMATION MONITOR AND DISPLACEMENT BACK ANALYSIS FOR BALIBIAN TUNNEL

To predicate the steady state of fracture surface of surrounding rock and support system in terms of Bali flat tunnel in the course of excavation and,uncover the mechanism of the tunnel surrounding rock in the aspect of deformation, destruction and stability. Exponential function model is established by the use of the data which is gained on spot in the way of testing the section of surrounding rock ZK77+835according to the horizontal convergence displacement and vault crown settlement displacement. The result, after the regression analysis, precise judgment and monitoring data analysis, Meanwhile conducting BP Neural Network displacement back analysis and numerical simulation, shows that by adopting the exponential function model, it is relatively precise to analysis of regression of the data acquired aiming at surrounding rockZK77+835 displacement; there are three periods of the deformation of surrounding rock, in the light of displacement and the dislocation rate, there will provide a basis for judging the stability of the fracture surface of surrounding rock and can start the secondary lining conduction after monitoring the 15 day; it is accurate to get the parameter of inversion by BP Neural Network displacement back analysis, which is taken to FLAC3D numerical model, there will be no different between the simulation results and the monitoring data in field.