The Determination Method Of Elastic Modulus Of Deep Damage Rock Mass

In recent years, many mines have been mined by the shallow into deep underground mining. With the increase of mining depth, the projects are affected obviously by high ground stress problems, especially the rock mass disturbance of mining stope blasting. Deep mining excavation under high geostress environment showed a special nonlinear mechanical behavior of surrounding rock, so that the traditional rock (stone) mechanics theory and analytical methods are faced with new challenges. Deep underground caverns in the excavation process, there will be a large number of microcracks on rock cavern surface. In the process of the secondary stress field adjustment, these micro-fractures are gradually extended, gradually leading to reduction of the integrity of the surrounding rock. Since the surface rock appears rib spalling, the board split and collapse phenomenon, it is difficult to test the elastic modulus of the rock surface damaged area by drill hole sampling, live on the surface by drilling damage zone sampling elastic modulus of rock tested, thus unable to determine the elastic modulus of damaged rock.(1) Based on the principle of damage mechanics and rock mechanics theory, we adopt the rock damage variable to study the elastic modulus of damage rock mass. Combined with borehole on site, sound wave test and the empirical formula about poisson’s ratio, rock mass density and rock mass velocity, the rock damage variable is determined.(2) We take the27#stope of-707levels in Hongtoushan Copper Mine as an engineering research background. Combined with the existing deep metal underground mining engineering studies, we apply the sound wave test, borehole camera and other means to the27#stope in-situ monitoring. Thus, combined with numerical simulation methods and empirical formula, we judge the preliminary damaged rock elastic modulus, and determine its approximate range.(3) Based on inverse analysis method of the genetic algorithm and neural network, applying the uniform design theory, and combined neural network with Rockmass Deterioration Model (RDM), elastic modulus of rockmass is inversed accurately, and then the distribution of elastic modulus of rockmass is obtained. Thus, the damage area of stope wall rock is delimited, the quantitative indexes of surrounding rock damage hierarchy is also got, and evolutionary regularity of surrounding rock damage with time distribution is received.