为进一步研究煤岩复合体水力压裂过程中裂缝的穿层扩展规律，开展了真三轴煤岩复合体水力压裂实验，通过改变应力差、压裂管的布置方向及注水点位置来比较裂缝的扩展效果和起裂难度。研究结果表明：水压裂缝的扩展方向受制于最大主应力，当最大水平主应力与最大垂直应力接近时，裂缝沿应力的合力方向扩展；应力差的增大有利于水压裂缝的穿层扩展，且穿层后的扩展距离增大，而对初始起裂压力和时间的影响较小；裂缝由岩层扩展进入煤层后，压裂压力会出现骤降与二次抬升，多数声发射事件位于煤层；若穿层失败，压力表现为持续波动。此外，在岩层中以垂直于交界面的方向布置压裂管，注水起裂点设在岩层中起裂难度较低，且穿层扩展后在煤层中形成的裂缝渗流通道较为完整，为工程中煤层增渗与顶板致裂卸压的应用提供理论基础。

To further study the law of hydraulic fracture penetration propagation through the layer in coal-rock complex, a true triaxial hydraulic fracturing experiment of coal-rock complex was carried out to compare the fracture extension effect and fracture initiation difficulty by changing the stress difference, the arrangement direction of fracture pipe and the location of water injection point.The research results show that the propagation direction of hydraulic fracture is restricted by the maximum principal stress, and when the maximum horizontal principal stress is close to the maximum vertical stress, the fracture expands along the resultant force direction of the stresses.The increase of stress difference is conducive to the penetration propagation of hydraulic fracture through the layer, and the propagation distance after the penetration increases, while a little influence on the initial fracture initiation pressure and time.After the fracture expands from the rock layer into the coal seam, the fracturing pressure will drop sharply and then rise again, and most of the acoustic emission events are located in the coal seam.If the penetration fails, the pressure fluctuates continuously.In addition, the fracture pipe is arranged in the rock seam in the direction perpendicular to the interface, and the water injection initiation point is set in the rock seam, the fracture initiation is much easier, as well as the fracture seepage channel formed in the coal seam after the penetration propagation through the seam is more complete, which provides a theoretical basis for the application of coal seam seepage enhancement and roof fracturing relief in engineering project.