土体气压劈裂的室内模型试验

气压劈裂是向岩土体中注入高压气体形成裂隙,增加流体的流动通道,从而提高低渗透性土体的渗透系数。通过室内模型试验探讨了土体在高压气体作用下的响应及劈裂现象。试验结果表明,向土体中喷入高压气体会在土体中生成超静孔压,超静孔压大小与喷气压力相关;超静孔压较大时,土体发生气压劈裂,生成的裂隙又为超静孔压的快速消散提供了通道,大部分超静孔压在裂隙闭合前消散;随着超静孔压的消散,裂隙随之减小,但不会完全闭合,留存残余微裂隙。

Model tests on pneumatic fracturing in soils

Pneumatic fracturing is the process of generation of fractures or extension of existing fractures in soils and rocks through the injection of high-pressure air into boreholes.The pneumatic fracturing has been utilized to increase the permeability of soils.A model test in laboratory is designed in this study to simulate the response of soils to the high-pressurized air.The model test results indicate that the injection of pressurized air into soil induces excess pore water pressure and also fractures the soils.The magnitude of induced excess pore water pressure is related to the pressure of the pressurized air.The fractures may function as channels for dissipation of the excess pore pressure.The fractures will close with dissipation of the excess pore pressure;however,a residual fracture is developed.