煤体脉动注水与恒压注水致裂特征模拟

Simulation of Coal Induce-crack Characteristics on the Conditions of Pulsatile and Constant Pressure Water Injections

为解决煤体恒压注水在实际应用中致裂效果不理想问题,基于FLAC3D在岩土力学中的应用,模拟了在脉动注水与恒压注水条件下煤体的起裂过程,分析了煤体脉动注水与恒压注水致裂特征。数值模拟结果表明,经水力压裂后,脉动注水模型中走向方向压裂半径3.3m,垂直方向压裂半径2.2m;恒压注水模型中走向方向压裂半径0.65m,垂直方向压裂半径0.96m。煤体脉动注水比恒压注水需要更长时间起裂,脉动注水模型最终压应力比恒压注水低,从而得出脉动注水对煤岩体卸压作用明显优于恒压注水。

To solve the problem that fracturing effect is not perfect in the practical applications of coal constant pressure water injection, based on the application of FLAC3D computer simulation to the rock and soil mechanics, the crack initiation process of the coal on the conditions of pulsatile and constant pressure water injections is simulated, the induce-crack characteristics of the coal on the conditions of pulsatile and constant pressure water injections are analyzed. The results of numerical simulation show that after hydraulic fracturing, the fracturing radius of the strike direction in the model of pulsatile water injection is 3.3m, the fracturing radius of the vertical direction is 2.2m; the fracturing radius of the strike direction in the model of constant pressure water injection is 0.65m, the fracturing radius of the vertical direction is 0.96m. The coal needed more time to crack initiation on the condition of pulsatile water injection than that of constant pressure water injection, the ultimate compressive stress for the model of the pulsatile water injection is lower than that for the model of the constant pressure water injection, a conclusion that the pulsatile water injection is significantly better than the constant pressure water injection in the pressure relief of the coal-rock is drawn.