Simulation On Crack Propagation Laws Of Hydraulic Fracturing Of Rockmass

The theory and technology of hydraulic fracturing have been developing along with the exploitation of oil and gas, and hydraulic fracturing technology is always an important measure to increase production of oil and gas in the oil industry. The hydraulic fracturing of rock is the unstable failure process of rock that is subjected to hydraulic pressure, characterized by the formation, growth and coalescence of micro cracks, as well as the initiation and development of macroscopic faults. The hydraulic fracturing theory has been applied to many engineering problems such as the stability of hydraulic structures, the water inrush of coal roof and floor, gas outburst, the handle of nuclear waste underground, the instability of dam, water outburst in tunnel and so on.Firstly, the general hydraulic fracturing mechanism of the rock mass was analyzed and summarized in this paper, and by using RFPA2D-Flow numerical computing systems and RFPA3D parallel computing systems, the two-dimensional and three-dimensional model of hydraulic fracturing were built to study the process of crack initiation, expansion, and instability under water pressure in different conditions. And then based on the water outburst instance in a mine, the process of roof water outburst was simulated and the mechanism was analyzed. This paper carries out the following research work:1. Different uniformity models was established by using RFPA3D parallel computing system, and then the impact of the rock uniformity on the length of the crack propagation and instability pressure was studied under the same other boundary conditions.2. Another model containing five holes and symmetry pressure gradient was established by using RFPA3D parallel computing system to analysis how the controlling holes affect the propagation direction of crack and analysis the space distribution law of the crack, and study the effect of fracture on the propagation direction of crack when water was injected into the coal seams with fractures.3. Firstly, the numerical simulation of "point" fracturing was carried out to study the crack propagation in the fracturing process. Then "point" fracturing equipment was used to conduct field test. And the feasibility of the application of the "point" fracturing in the project site was analyzed.4. The roof water burst of a domestic mine was simulated to study the whole damage and failure process of rock driven by water pressure by using RFPA2D-Flow from the viewpoint of coupled flow-damage interaction.