Study On The Deformation And Failure Mechanism Of Donggushan Copper Mine’s Surrounding Rock Under Frequent Vibrations

Abstract:It’s very common in the large and deep metal mines that the bottom structure is under high geo-stresses and frequent vibrations.As a result, the stability of the surrounding rock in such mines is hard to guarantee. This thesis combines the project--"the research of the rock damage mechanism and its control technology under complicated conditions when the large-scale high-stress dynamics disturb the multi-paneh multi-stope mine", and taking Donggushan copper mine as the background. The deformation and failure Mechanism of mine roadway of Donggushan copper mine is studied through theoretical analysis, field monitoring, laboratory experiment and numerical simulation. Content and the main results are as follows:(1) The blasting vibration velocity of the surrounding rock is measured by field monitoring.By combining with the theory model analysis, it is validated that the blasting of Donggushan mine is likely to destroy the far district surrounding rock. The cumulative damege in the surrounding rock has been calculated after several repeating blastings.(2) Mechanical experiments of rock under high stress and cyclic dynamic disturbance have been done. The following results have been concluded:The average stress and amplitude of the cyclic dynamic disturbance have significant influences on the fatigue life of rock, the relationships between the fatigue life of rock and the cyclic numbers accords with the negative index; With the increase of the impact numbers, the elasticity modulus of the rock rises at first and then it decreases. On the contrary, the maximum strain exhibits an overall trend of decreasing firstly and then it increases. The rock samples under cyclical impacts show a mode of splitting failure, while other rock samples show a shear failure and tensional fatigue failure in cyclic loading and unloading tests. (3) Using FLAC3D software to build a numerical tridimensional dynamic model for Donggushan copper mine. The mechanics parameters deterioration laws of rock mass as well as the regularities of stress, plastic region, and displacement in the surrounding rock which is under stress redistribution and blasting vibration have been studied in the model.(4) The support effect of the roadway has been studied by numerical simulation and field investigation. The main problems of the support system are:local stress concentration in the surrounding rock, the tensile strength of the bolt is not enough; the deformation and displacement of the roadway is too large, the stiffness of concrete structure does not meet the requirement and the surrounding rock has been badly destroyed in a fractured way.