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为探究人工冻结砂土与结构接触面冻结强度影响因素及其规律,揭示冻结强度形成机制,利用自行研制的大型冻土直剪仪开展冻结强度试验研究。结果表明:人工冻结砂土与结构接触面冻结强度受接触面温度、法向应力、粗糙度等因素影响显著;冻结强度均随接触面温度降低而增大,其中极限冻结强度随接触面温度降低而线性增大,残余冻结强度随接触面温度变化呈现持续稳定、先波动后稳定及循环波动3种典型规律;冻结强度均随法向应力增大而增大,其中极限冻结强度与法向应力关系符合莫尔–库仑定律,残余冻结强度随法向应力变化呈现同样3种典型规律;冻结强度均随粗糙度增大而增大,其中极限冻结强度与粗糙度满足对数函数关系,残余冻结强度曲线波动式循环周期随粗糙度增大而增大。进一步揭示接触面冻结强度形成机制,并对残余冻结强度呈现黏滑现象作出合理解释。通过接触面冻结强度多影响因素综合分析,给出极限冻结强度与接触面温度、法向应力、粗糙度的经验公式,可用于预测极限冻结强度值。
In order to explore the influencing factors and regularities of the freezing strength of the contact surface between the artificial frozen sand and the structure and to reveal the formation mechanism of the freezing strength, the freezing strength test of the large frozen soil direct shear tester developed by ourselves was carried out. The results show that the freezing strength of the contact surface between the artificial frozen sand and the structure is significantly affected by the contact surface temperature, the normal stress and the roughness. The freezing strength increases with the decrease of the contact surface temperature, and the ultimate freezing strength decreases with the contact surface temperature While the linear increase, the residual freezing strength with the contact surface temperature showed a continuous stability, the first wave after the stability and circulation fluctuations of three typical laws; freezing strength increases with the normal stress increases, of which the ultimate freezing strength and normal stress The relationship is in accordance with the Mohr-Coulomb law, and the residual freezing strength shows the same three typical laws with the normal stress. The freezing strength increases with the increase of the roughness. The ultimate freezing strength and the roughness satisfy the logarithmic function, and the residual freezing Intensity curve fluctuating cycle increases with increasing roughness. Further reveal the formation mechanism of the contact surface freezing strength, and make a reasonable explanation of the phenomenon that the residual freezing strength is stick-slip. Based on the comprehensive analysis of many influencing factors on the freezing strength of contact surface, empirical formulas of ultimate freezing strength, interface temperature, normal stress and roughness are given, which can be used to predict the ultimate freezing strength value.