Research On Prediction Method Of Surrounding Rock Pressure Base On Tunnel Progressive Destruction

This article unifies the"the highway tunnel relaxation load prediction theory and the early warning system(No.200631874024)"of Ministry of Communications technological project, evolves two angles embarking from the surrounding rock classification and the surrounding rock damage, relates the scene monitoring gauging data elastic vertical wave velocity, unions numerical value simulation analysis as well as theoretical analysis methods and so on, analyzes the surrounding rock pressure evolution tendency of the tunnel surrounding rock, focus on studying for the highway tunnel relaxation load forecast model, as fllows:⑴Starting with the surrounding rock classification and the initial damage's relativity, it analyzes and discusses the damage evolutionary process of surrounding rock during tunnel digging process.Then it establishs the connection between the damage variable and the surrounding rock mechanics parameters, namely it has been established the conectin between the elastic wave vertical wave velocity and the surrounding rock mechanics parameters.⑵According to the damage mechanics theory of stability analyses of surrounding rock in the underground hole room under the condition of discharge load, it adopts the method which is based on the DP criterion dynamic change parameters of surrounding rock, researching for the ANSYS numerical simulation during the digging process of the surrounding rock, establishs macroscopic mechanical model of sections tunnel surrounding rock's evolution destroys during the process of digging and discharging load,⑶According to the results of numerical simulation, it analyzes surrounding rock's displacement, stress, strain as well as the plastic area's distributed situation, then obtains the gradual destruction rule of tunnel surrounding rock.⑷Duing to the relation between surrounding rock classification and the sound wave velocity, which improved the Bieniawski empirical formula, promoted the surrounding rock pressure forecast model, which is based on the empirical formula; At the same time,we have established another surrounding rock pressure forecast technique according to the tunnel surrounding rock's evolution failure theory.⑸Based on the monitoring data of Bi-cheng Tunnel, it compares the data of forecast models with the monitoring data. The result shows that: these two kind of models tally with the surrounding rock pressure evolved tendency in the actual situation. The computation parameter of this model is simple and objective. The models have high value on the project practical.This article highlights:⑴It sets up a damage variable and mechanical parameters of rock mass surrounding the relationship between;⑵It sets up a tunnel progressive damage ANSYS simulation model ;⑶It mades a prediction model based on the surrounding rock pressure;⑷It mades a prediction model by the theory of progressive rock pressure damage.