水力劈裂裂隙扩展与软弱面作用机理离散元研究

Discrete Element Investigation on the Interaction of Hydraulic Fracturing and Weak Plane in Deep Tunnels

针对高承压水引发水力劈裂导致巷道的突水渗水问题,对离散元流固耦合算法进行改进,更新了流体通道长度和水压力对颗粒的作用模式.进行水力劈裂裂隙(HFs)与天然软弱面(WPs)相互作用的数值模拟,得到5种作用模式,并获取不同模式之间的临界水压力值,进一步分析了试件的位移、接触力以及特征点的应力变化.结果表明:1)定压力注水试验,流体压力值在初始注水处最大,沿裂隙扩展方向逐渐减小;2)不同模式下试样位移响应具有差异性,法向接触力接触方向存在明显竖直优势面,切向接触力则产生4个垂直的优势方向;3)测量圆1处应力在起裂阶段变化剧烈,最大主应力始终为压应力,测量圆2处应力响应相对滞后,主应力曲线的特征是由劈裂裂隙和软弱面之间的作用模式决定.

Hydraulic fracturing caused by high confined water is the root cause of water inrush in roadway.The discrete element fluid-solid coupling algorithm was improved,and the action mode of fluid channel length and water pressure on particles was updated.The interaction between the hydro-splitting fractures(HFs)and the weak planes(WPs)was simulated.Five different modes were obtained and the critical pressure values were calculated.The displacement,contact force of the specimen and the various of the stress at a specific point were analyzed.The research shows that:1)with a constant injection pressure,the pressure value is the largest at the initial crack,then gradually decreases along the crack.2)the displacement response are different under five interaction modes.The normal contact force has obvious vertical dominant surface in its contact direction,and the shear contact force generates four vertical dominant distribution directions.3)the stress at Mc1 changes dramatically during the initiation stage,and the maxmium principal is always compressive.Stress response in Mc2 is relatively hysteretic.The diversity of principal stress is fundamentally determined by the interaction mode between HFs and WPs.