Research On Rules Of Dynamic Response Of Fractured Rock Mass To Blasting

Abstract A large number of joints, fissures and other structural plane are developing in natural rock. Rock is cut into different shapes of blocks. According to Shi Genhua’s block theory, these blocks can be classified as stable, potential unstable, and instability. Potential unstable block is usually exposed to the free surface, and destroyed along the structural surface, under repeated blasting. Study on the influence of blasting power of fractured rock mass engineering has important practical significance.Tong-keng mine is the background of this paper. With field measurements, field test, theoretical analysis and numerical simulation, this paper made a comprehensive analysis of fractured roadway under the blasting dynamic disturbance. The main contents are as follows(1) Development of joint fracture was determined by geological survey, and a roadway was selected as the object of the study. Based on block theory, the potential unstable blocks, which surrounding the roadway,were extracted and classified by the software,(2) The relevant blasting vibration data was acquired by on-site blasting vibration test. The attenuation coefficient associated k,a were calculated by MATLAB.(3) The finite element model of different structural plane was built. Thickness, angle and material properties of the structural plane, which influence the propagation of stress wave,were analysised. Results showed that wave attenuation degree approximate proportional to thickness of the plane.The greater the plane angle, the greater the obstacle to the wave. If the material, filling in the plane, has more differences with the rock, the hinder of the plane will be greater.(4) Finite element model for blasting dynamic response of fracture roadway was built by ANSYS. Rule of the dynamic response of the roadway was analysised.Through the analysis of the particle velocity, displacement and stress, some results was got. The results showed that:the peak particle velocity was in safe range, but the tensile will appear along the structural plane,whicn developing in the top and side of the roadway. If the tensile stress is large enough, it may cause damage to the plane, and eventually leading to instability of the rock.