关键词: 低温裂隙岩体, 裂隙冻胀力, 冻胀试验, 演化过程, 冻胀扩展

Abstract: Freeze-thaw damage and rupture failure of fractured rock mass under low temperature are the key scientific problems for the construction of rock engineering in cold regions. Frost heaving pressure produced in saturated crack is a controlling factor that induces crack frost propagation. However, the magnitude and evolution law of frost heaving pressure are controversial due to the difficulty in conducting tests. By prefabricating macroscopic crack with different geometries in rock-like material, a laboratory test of frost heaving pressure in saturated cracks is conducted. A thin film pressure sensor is used to test the evolution process of frost heaving pressure in cracks and the temperature on the surface of rock is continuously monitored by several temperature sensors. Based on the results, the space-time evolution curves of frost heaving pressure in cracks are derived. The experimental results show that: 1) In freezing process, the initiation of frost heaving pressure in crack suddenly occurs, and the entire evolution process of this pressure can be divided into embryonic stage, outburst stage, falling stage and balance stage. 2) In frozen process, the ice in crack has been extruded and new visible propagation cracks are produced in tips of the cracks. 3) In melting process, the frost heaving pressure falls quickly but lags behind the freezing point. 4) For a half open fracture with a width ranging between 2?5 mm, when water starts freezing at the open end, the maximum frost heaving pressure linearly increases with the increasing of crack width. The pressure is more than 7.2 MPa in saturated crack with a width of 5 mm. Research results presented in this paper can provide reference for understanding the evolution mechanism of frost heaving pressure and studying the crack propagation caused by frost heave.

Key words: fractured rock mass under low temperature, frost heaving pressure in crack, frost heaving experiment, evolution process, frost heaving propagation