冻结裂隙砂岩的力学特性研究

Study on the Mechanical Properties of Frozen Fractured Sandstone

为得出围压、裂隙倾角、冻结温度等因素对砂岩力学性能的影响规律,采用三轴压缩试验方法和理论分析方法,研究了不同围压下,无裂隙0°,15°,30°和45°倾角裂隙砂岩在-5℃,-10℃和-15℃冻结时的强度、内摩擦角和粘聚力变化特征。结果表明:无裂隙和有裂隙砂岩的强度,随冻结温度的降低而非线性增强,随围压的降低而近线性降低,随裂隙倾角的增大而减小;粘聚力随冻结温度的升高而减小,内摩擦角和粘聚力均有随裂隙倾角的增加而先减小后增大的变化趋势;无裂隙,0°,15°倾角裂隙砂岩的内摩擦角均随冻结温度的升高而减小,30°倾角裂隙砂岩的内摩擦角随冻结温度的降低先增大后减小,45°倾角裂隙砂岩的内摩擦角则随冻结温度的降低先减小后增大。

In order to derive the influence patterns of confining pressure,fracture dip angle and freezing temperature on the mechanical properties of the sandstone,this paper uses the triaxial compression test method and theoretical analysis method to study the changing characteristics of the strength,internal friction angle and cohesion of sandstones without fracture and fractured sandstones with dip angles of 0°,15°,30°and 45°at frozen temperatures of-5℃,-10℃and-15℃under different confining pressures.The results show that the strengths of fracture-free and fractured sandstones increase nonlinearly with decreasing of freezing temperature,decrease nearly linearly with decreasing of confining pressure,and decrease with increasing of fracture dip angle;the cohesions decrease with the increase of the freezing temperature,and both the internal friction angle and cohesion have the tendency to decrease first and then increase with the increase of the fracture dip angle;and the internal friction angles of fracture-free sandstone and fractured sandstone with 0°and 15°dip angles all decrease with the increase of the freezing temperature,the internal friction angle of fractured sandstone with 30°dip angle increases first before decreasing with the decrease of the freezing temperature,and the internal friction angle of fractured sandstone with 45°dip angle decreases first before increasing with the decrease of the freezing temperature.