裂隙重合度对砂岩力学性质及损伤演化的影响

    Effect of Fracture Coincidence on Mechanical Properties and Damage Evolution of Sandstone

    • 摘要: 为了研究裂纹重合度对裂隙砂岩力学性质和损伤演化规律的影响,利用RFPA2D软件对5种裂纹重合度的砂岩试样进行了单轴压缩试验数值模拟,分析不同裂纹分布条件下的力学特性、声发射特性和损伤演化过程。结果表明:预制裂纹重合度越接近100%,平行裂隙砂岩试样的峰值强度和起裂强度越大,声发射计数量也随之增多;裂纹扩展都是由翼裂纹萌发开始,不同裂纹分布情况下,翼裂纹发展的趋势有明显差别,裂纹重合度小于100%时会出现岩桥贯通现象;当裂隙重合度接近100%时,有其中1条翼裂纹主导破裂过程,发育过程较慢,强度相对越高;而当裂纹重合度大于100%时,两端的翼裂纹相对独立的扩展直至形成贯通裂纹,裂纹发展速度快,加速了破坏失稳的形成。

       

      Abstract: To study the effect of fracture coincidence on mechanical properties and damage evolution of fractured sandstone, five kinds of sandstone specimens with different crack distributions were simulated by RFPA2D software under uniaxial compression test. The mechanical properties, acoustic emission characteristics and damage evolution process under different crack distributions were analyzed. The results show that the closer the coincidence degree of prefabricated cracks is to 100%, the greater the peak strength and initiation strength of sandstone samples with parallel cracks, the more the number of acoustic emission counts will increase. Crack propagation starts from the initiation of wing cracks. Under different crack distribution, the trend of wing crack development is obviously different. When the coincidence degree of cracks is less than 100%, the acoustic emission counts will increase. When the crack coincidence is more than 100%, the crack will not penetrate at the rock bridge, but the wing crack at both ends will propagate independently until it forms a penetrating crack.

       

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