The Model Tests And Study On Forming Mechanism Of Zonal Disintegration In Deep Rock Mass

Over the years, the proportion of deep underground cavern project in underground engineering is growing, there are some new discoveries of rock fracture phenomena in the deep tunnel. In the complex case of the high stress, high temperature, large disturbance conditions, the deep rock mass destruction appeared distinct from the shallow rock breakage, which zonal disintegration phenomenon is very interesting. This paper supported by the National Natural Science Foundation of China, taking the Huainan mining area Dingji deep mine roadway as background, based on similar principles of model test, relying on independently developed large-scale three-dimensional geomechanical model test system,taking geomechanical model tests in the different cavern shapes, stress loading directions and geological conditions that is very important to influencing factors and formation mechanism of zonal disintegration. In this paper, the research work and related results are as follows:(1) The self-developed high geo-stress true3D loading model test system can be used to apply triaxial high stress synchronization and independently, the maximum pressure is31.5Mpa.(2) Through the model test of the axial compression on the cavern obligated, it is found that the axial high geo-stress is the important factor which lead to the zonal disintegration.(3) Through the model tests in citygate-shaped, rectangular-shaped reproduce the phenomenon of zonal disintegration.Draw that in the of power excavation and the magnitude of initial maximum principal stress parallel to the hole axis direction more than1.5times of the compressive strength of the surrounding rock is the important condition to the zonal disintegration appearing; the longitudinal cracks of zonal disintegration substantially parallel to axis; the range of the zonal disintegration relates to the hole shapes,caverns size,the longer of the cavern diameter or width, the greater ranger of the zonal disintegration; The zonal disintegration independent of the carven shapes, the outermost boundary are approximated circular shapes in zonal disintegration;the average radius ratio of the two adjacent destruction between1.3～1.4, in line with (?)2modulus relationship,that ri=(?)2ri-1(i=1,2,3,4),i is the number of the rupture zone, r0is the radius or width of the cavern.(4) When the test model containing interlayers in the of power excavation and the magnitude of initial maximum principal stress parallel to the hole axis direction more than1.5times of the compressive strength of the surrounding rock,the phenomenon of zonal disintegration appears.(5) Through initial maximum principal stress parallel and perpendicular to the hole axis direction model test and found that when the initial maximum principal stress vertical axial hole, the model plastic loose circle of damage zone appears, which does not appear the phenomenon of zonal disintegration.(6) Based on the strain energy density theory successfully reproduced the phenomenon of zonal disintegration with numerical simulation. In the numerical simulation of zonal disintegration, the rupture area, rupture zone layers, ratio of the maximum extent of damage with the hole diameter are basically same with the model test results; the displacement variation in numerical simulation with model test measured law is basically the same, showing changes in the wavy.