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.