Crack propagation can gradually reduce the strength of the rock and eventually result in rock failure. Coupling effect of stress and seepage in fracture could accelerate the rock failure process. In this work, a set of water sealing device is developed to apply different fluid pressures in the pre-existing fracture in specimens made of rock-like material. We have carried out uniaxial compression tests on specimens at different pre-existing flaw dip angles (30°, 45°, and 60°) coupled with fluid pressures in the fracture. Through laboratory experiments and numerical simulations, we find that without fluid pressure in the pre-existing flaw, wing cracks and secondary cracks appear at the pre-existing flaw tips. With the increase of the fluid pressure in the flaw, the propagation of secondary cracks is restrained, no secondary cracks appear at the flaw tips. The increase of fluid pressure accelerates the wing crack propagation, inhibits the secondary cracks, and causes the specimen to undergo tensile failure. Compared with the specimen without the fluid pressure in the flaw, the fluid pressure in the flaw promotes wing crack initiation and propagation, and causes the initiation stress of the wing cracks and the peak strength of the specimens to decrease gradually. With or without fluid pressure in the fracture with the increase of the flaw dip angle, the initiation stress of wing cracks and peak strength of the specimen first decrease and then increase. When the pre-existing flaw dip angle is 45°, the peak strength and the initiation stress are the lowest.

中文翻译：

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单轴压缩下具有流体渗透预存缺陷的类岩石材料的裂缝扩展

裂纹扩展会逐渐降低岩石的强度，最终导致岩石破坏。裂缝中应力和渗流的耦合作用会加速岩石破坏过程。在这项工作中，开发了一套水封装置，以在由类岩石材料制成的试样中的预先存在的裂缝中施加不同的流体压力。我们在不同的预先存在的缺陷倾角（30°、45° 和 60°）以及裂缝中的流体压力下对试样进行了单轴压缩试验。通过室内实验和数值模拟，我们发现在原有缺陷没有流体压力的情况下，原有缺陷尖端会出现翼状裂纹和二次裂纹。随着缺陷内流体压力的增加，二次裂纹的扩展受到抑制，裂纹尖端无二次裂纹出现。流体压力的增加加速了翼形裂纹扩展，抑制了二次裂纹，使试件发生拉伸破坏。与裂纹中没有流体压力的试件相比，裂纹中的流体压力促进了翼裂纹的萌生和扩展，使翼裂纹的萌生应力和试件的峰值强度逐渐降低。随着裂纹倾角的增加，裂缝内有无流体压力，翼形裂纹的起始应力和试件的峰值强度先减小后增大。当预存缺陷倾角为45°时，峰值强度和起始应力最低。抑制二次裂纹，并使试样发生拉伸破坏。与裂纹中没有流体压力的试件相比，裂纹中的流体压力促进了翼裂纹的萌生和扩展，使翼裂纹的萌生应力和试件的峰值强度逐渐降低。随着裂纹倾角的增加，裂缝内有无流体压力，翼形裂纹的起始应力和试件的峰值强度先减小后增大。当预存缺陷倾角为45°时，峰值强度和起始应力最低。抑制二次裂纹，并使试样发生拉伸破坏。与裂纹中没有流体压力的试件相比，裂纹中的流体压力促进了翼裂纹的萌生和扩展，使翼裂纹的萌生应力和试件的峰值强度逐渐降低。随着裂纹倾角的增加，裂缝内有无流体压力，翼形裂纹的起始应力和试件的峰值强度先减小后增大。当预存缺陷倾角为45°时，峰值强度和起始应力最低。使翼裂纹的起始应力和试件的峰值强度逐渐降低。随着裂纹倾角的增加，裂缝内有无流体压力，翼形裂纹的起始应力和试件的峰值强度先减小后增大。当预存缺陷倾角为45°时，峰值强度和起始应力最低。使翼裂纹的起始应力和试件的峰值强度逐渐降低。随着裂纹倾角的增加，裂缝内有无流体压力，翼形裂纹的起始应力和试件的峰值强度先减小后增大。当预存缺陷倾角为45°时，峰值强度和起始应力最低。