人工冻结砾石土三轴剪切强度试验研究

Experimental Study on Triaxial Shear Strength of Artificially Frozen Gravel Soil

为分析冷冻温度和含水量对于砾石土抗剪强度参数的影响,通过室内试验对南宁地铁联络通道砾石土层进行冻结状态下的三轴剪切强度分析,研究围压、冷冻温度以及含水量对于其强度演变的影响,分别得到几个特征围压下的砾石土冻结强度与冷冻温度及含水量的关系。试验结果表明:砾石土的三轴剪切强度随着冷冻温度的降低而升高,温度效应明显;同时,含水量变化对于其剪切强度影响也十分显著,在试验研究范围内冻结砾石土偏应力峰值与含水量成一定的正相关性,随着含水量增加,冻结冰晶体含量随之升高进而引起土体胶结能力增大,相应的强度有所提升。该三轴剪切强度符合Mohr-Column准则,黏聚力与内摩擦角随着冷冻温度的降低而增大,随着含水量的增加而增加。同时,冷冻温度对于砾石土三轴剪切强度参数的影响受土体含水量变化影响显著。

In order to analyze the effects of freezing temperature and water content on the shear strength parameters of gravel soil,the three axis shear strength of the gravel soil layer of Nanning Metro liaison channel under freezing condition is tested in laboratory,in which the influences of confining pressure,freezing temperature and water content on its strength evolution are investigated.The relationships between freezing strength,freezing temperature and water content of gravel soil under several characteristic confining pressures are obtained.The test results demonstrate that the triaxial shear strength of the artificially frozen gravel soil shows an obvious increase with the decrease of freezing temperature,and the effect of temperature is obvious.Meanwhile,the water content has great influence on the three axis shear strength of the frozen gravel soil,and there is a positive correlation between the two.The cementation capacity of soil and the corresponding strength increase with the increase of water content of frozen ice crystals.The shear strength of the three axis conforms to the Mohr-Column criterion,while the cohesion and internal friction angle increase with the decrease of freezing temperature,and rise with the increase of water content.The effect of freezing temperature on three axis shear strength parameters of gravel soil is greatly influenced by the change of soil water content.