Research On The Mechanism And Evolution Law Of Rock Deformation And Cracking Around Deep Tunnels

Along with the increase of coal mining depth, the problem of rock stabilization around deep tunnels is getting more and more prominent, which influences seriously the security, economical and highly effective development. To solve this question reasonably, the key and the most important task is to master correctly the mechanism and evolution law of rock deformation and cracking induced by engineering disturbances around the tunnels, so as to provide theoretical basis for designing the rock support scheme with reliable in safety and reasonable in economy. Under the fund of National Natural Science Foundation of China (project number 50674083) and the Key Project of Science and Technology in the Ministry ofEducation(project number 106085), this dissertation investigates the evolution features and mechanism of rock deformation and cracking during the excavation of a deep tunnel, and studies the intelligent simulation and prediction of the evolution law of rock deformation by means of physical and numerical simulations as well as theoretical analysis. The detail research contents and conclusions are as follows:(1) The transparent simulation material and test equipment for the modeling of deep tunnels are developed, and the photo taking technique is improved by using the laser source and fluorescent powder simultaneously. A new effective method of determining the PFC model parameters is put forward, which uses the technologies of numerical orthogonal tests and artificial intelligent prediction.(2) The physical and numerical simulations of the rock deformation and cracking process during tunnel excavation are conducted, and the results show that the rock deformation process presents the characteristics of oscillation wave and that the distribution of cracking areas presents zonal feature.(3) Based on the analysis of evolution law of rock deformation and cracking, the wave theory is introduced into the research of rock cracking mechanism, and the conceptual model of"spring and oscillator"for surrounding rock is founded. It is revealed that the oscillation induced damage is the essential cause of rock deformation and cracking, and the intrinsic reasons of different cracking forms are rock damp, wave length, stress state and energy supply.(4) To solve the difficulty in quantitatively represent and predict the evolution law of rock deformation, based on the superposition principle of wave, the wave of rock deformation is divided into two parts, the static component and the dynamic one; the intelligent simulation and prediction model of rock deformation law is established by using technologies of artificial intelligence. The prediction results show that the intelligent simulation is a simple and efficient representation method of rock deformation law.The research findings obtained in this dissertation give direction for further study on the evolution law of rock deformation around tunnels by means of theoretical analysis. The achievements are of great significance in both theory and reality because mastering the exact evolution trend of rock deformation and cracking around deep tunnels would be very helpful to the prevention of potential geologic hazards.