关键词: 冲积层, 冻土力学, 力学特性, 温度, 蠕变

Abstract: The freezing technology for constructing deep shafts and long inclined shafts is always a key and difficult point in mine construction on complex geological conditions. The construction of shafts with complex engineering specifications in areas with deep, complex formation conditions needs to use freezing process in alluvium of thousands of meters thick. To obtain the physical and mechanical parameters of frozen soil in deep alluvium, undisturbed soil samples were collected at ten horizons (-193m~-624m) at the construction site. Then, the physical and mechanical parameters of the remolded frozen soils at the ten horizons were detected in the laboratory. The experiment showed that at the same freezing temperature, the frozen soil at the second horizon showed the largest frozen-heave force, followed by that of the eighth horizon, while the lowest frozen-heave force was observed at the ninth horizon. After being frozen, the soil at the fifth horizon presented the highest uniaxial compressive strength and desirable freezing stability of the formation. In comparison, the frozen soil at the eighth horizon exhibited the lowest uniaxial compressive strength and poor freezing stability of the formation. The cohesion of the soils at the fourth to sixth horizons was sensitive to the influences of freezing temperature. After being frozen at -15°C, the clay at the third to fifth horizons had relatively larger shear creep deformation while being sheared under different constant stresses. Meanwhile, structural characteristics and moisture content of the soil in the formation, temperature, stress and time are key factors influencing the strength of the frozen soil. The research results can be directly used to guide the design and construction of frozen walls of shafts to improve the design and construction quality.