(1. State Key Laboratory of Coal Mine Disaster Dynamics and Control，Chongqing University，Chongqing 400030，China；2. College of Resources and Environmental Sciences，Chongqing University，Chongqing 400030，China)
Abstract：The loading-unloading tests to gas-bearing shale under the true triaxial stress conditions with different intermediate principal stresses were carried out with the multifunctional true triaxial test system developed in house for fluid-solid coupling to explore the influence of intermediate principal stress and bedding direction on mechanical properties and permeability characteristics of shale. The results indicate that the effect of intermediate principal stress on the permeability of shale is greatest when the intermediate principal stress is perpendicular to the bedding plane，is lower when the minor principal stress is perpendicular to the bedding plane，and is lowest when the maximum principal stress is perpendicular to the bedding plane. When the intermediate principal stress is perpendicular to the bedding plane or parallel to the bedding plane，the intermediate principal stress is negatively correlated with the permeability. The permeability is more sensitive to the intermediate principal stress when the intermediate principal stress is perpendicular to the bedding plane than parallel to the bedding plane (the difference is 1 or 2 orders of magnitude). In addition，the expression of the damage variable D was defined. The slope of the damage variable-intermediate principal stress curve changes little during the loading process and changes obviously during the unloading process. The damage variable is bigger when the intermediate principal stress is perpendicular to the bedding plane than parallel to the bedding plane during the whole process.
蒋长宝1，2，陈昱霏1，2，尹光志1，2，刘 超1，2，段敏克1，2. 中间主应力与层理方向对页岩力学和渗透特性影响的试验研究[J]. 岩石力学与工程学报, 2017, 36(7): 1570-1578.
JIANG Changbao1，2，CHEN Yufei1，2，YIN Guangzhi1，2，LIU Chao1，2，DUAN Minke1，2. Experimental study on the effect of intermediate principal stress and bedding direction on mechanical properties and permeability of shale. , 2017, 36(7): 1570-1578.
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2017, Vol. 36 
