Study On The Stability Of Adjacent Rock Mass With Schistosity Structure For Shrinkage Method

Many rock mass engineering activities show that the deformation and failure law of rock mass primarily depends on its structural characteristics and the structure of rock mass is one of the major factors which control the stability of rock mass engineering. Schistosity is an important kind of structure of rock mass .Combined with the project of'Technology of ground pressure control under high crustal stress and the mining plan research in Yinshan Mine', the stability of schistosity structural stope is studied. Using methods of field survey, laboratory and site rock mechanical parameter test, similarity simulation experiments, numerical simulation and field monitor ,some qualitative and quantitative results are obtained .Meanwhile, the plan for controlling the deformation and failure models for rock mass with schistosity structure are proposed .The main content and conclusion are summarized as follows:(1)Based on the field survey and the classification of the petrofabric of engineering geology , the main cause of collapsing and caving of stope and pillar is analysed ,and it is proved that the schistosity structure is a main factor of stope stability.(2) Rock mechanical parameter test and proportioning similar material test are carried .By similarity simulation experiments from three different cross sections at -195m level ,it can be found that rock mass with schistosity structure around the stope to lose steady is the failure of crack in compressiveand tensile with the structure losing stability primarily and it's material secondly .Meanwhile, according to the study on the change rule of the stress and strain of the rock mass with schistosity structural foundation, the plan to control the deformation and failure to rock mass with schistosity structure by establishing pillars in the different space position is propose . (3) Numerically simulation using by distinct element and finite element to the stabilization for stope of rock mass with schistosity structure , results indicate that it is easy to occur diabrosis failure and flexural failure on the stope of rock mass with schistosity structure in center lower part of the hanging wall, but in bottom wall ,tension fracture failure along the bedding plane easier ,which is consistent with the mechanism of failure of slaty cleavage medium which proposed by Sun Guangzhong .At the same time, the judgment is also confirmed that the pillar acts a certain part to control the stope stability of rock mass with schistosity structure, which is the same result as the similarity simulation experiments . The generalized analysis result of the failure process, the forecast and control of stabilization for stope of rock mass with schistosity structure can scientificly guide similar engineering activities in a certain degree.(4) Field monitoring result about the stope of rock mass with schistosity structure indicated that the stress is not suitable for stability analysis of rock mass with schistosity structure around stopes, and the viewpoint with rock mechanics of slaty cleavage medium to should be adoptable.