流固耦合作用下页岩破裂过程的数值模拟

Numerical simulation of rupture process of shale under action of fluid-solid coupling

为探究流固耦合作用下页岩的破裂过程和声发射特征,利用RFPA^2D-Flow数值软件分别对黔北地区牛蹄塘组不同层理倾角页岩进行流固耦合数值模拟。研究表明:由于层理结构的影响,页岩抗压强度和弹性模量均表现出明显的各向异性。页岩的破裂过程可分为弹性、屈服和破坏3个阶段,随着层理倾角的变化,页岩最终表现出3种破坏模式,分别为斜I型、V型和火焰型。层理倾角不同的页岩,其破裂过程中的声发射信号演化规律不同。对低层理倾角(0°、15°、30°)的试样,累计AE曲线表现为"平缓—线性—台阶—平缓"的变化规律;高层理倾角(60°、75°、90°)试样的累计AE曲线呈现"平缓—线性—陡增"的变化规律;当a=45°时,累计AE曲线表现为"平缓—线性—激增—平缓—激增"的变化规律,且其AE计数出现两个峰值。

In order to investigate the rupture process and acoustic emission characteristics of shale under fluid-solid coupling,the numerical simulation of fluid-solid coupling of the Niutitang Formation shale in different bedding angle in the northern part of the Qianbei area was carried out by RFPA^2D-Flow numerical software.Studies have shown that due to the influence of the bedding structure,the compressive strength and elastic modulus of shale show obvious anisotropy.The rupture process of shale can be divided into three stages:elasticity,yielding and destruction.With the change of the bedding angle,the shale finally showed three failure modes,namely oblique I,V and flame.Shale with different bedding dips has different evolutionary rules of acoustic emission signals in the process of fracture.For samples with low bedding angles(0°,15°,30°),the cumulative AE curve shows a change pattern of“smooth-linear-step-smooth”.The cumulative AE curve of the high-rise dip angle(60°,75°,90°)shows a change pattern of“smooth-linear-steep increase”.Whena=45°,the cumulative AE curve shows a change pattern of“smooth-linear-boost-gradual-boost”,and its AE count shows two peaks.