冻融循环作用下石墨尾矿抗剪强度特性研究

Shear strength characteristics of graphite tailings under freeze-thaw cycle

以季节性冻土区黑龙江省鹤岗市萝北县的石墨尾矿为研究对象,研究了冻融循环对3种相对密度下冻结石墨尾矿抗剪强度的影响规律,建立了冻融循环次数对黏聚力和内摩擦角影响的拟合公式,提出了冻融循环作用下抗剪强度修正公式。结果表明:相对密度越大,抗剪强度、黏聚力和内摩擦角劣化程度越小,提高相对密度对提高抗剪强度非常有利。随冻融循环次数的增大,抗剪强度、黏聚力和内摩擦角均减小,1次冻融循环后抗剪强度劣化效果最显著,5次冻融循环后基本趋于稳定,当相对密度为30%、60%和90%时,5次冻融循环后,抗剪强度分别降低了31.4%、27.8%和20.7%,黏聚力分别降低了55.0%、41.4%和32.9%,内摩擦角分别降低了17.0%、15.1%和13.5%。建议将5次循环后的抗剪强度参数作为计算分析的参考指标,研究成果可供我国季冻区石墨尾矿相关工程建设及冻害防治等参考。

The shear strength of graphite tailings in Luobei county of Heilongjiang Province were the research object under three relative densities are studied.The fitting formula of the influence of freeze-thaw cycles on the cohesion and internal friction angle were presented effects of freeze-thaw cycles,and the correction formula of shear strength under the action of freeze-thaw cycles are given as well.The results show that the higher the relative density,the smaller the deterioration degree of the shear strength,cohesion and internal friction angle,and the increase of the relative density is very beneficial to improve the shear strength.With the increase of the number of freeze-thaw cycles,the shear strength,cohesion and internal friction Angle all decrease.The deterioration effect of the shear strength after one freeze-thaw cycle is the most significant,and the shear strength basically becomes stable after five freeze-thaw cycles.When the relative density is 30%,60%and 90%,the shear strength after five freeze-thaw cycles decreases by 31.4%,27.8%and 20.7%,respectively.Cohesion decreased by 55.0%,41.4%and 32.9%,and internal friction Angle decreased by 17.0%,15.1%and 13.5%,respectively.It is suggested that the shear strength parameters after 5 cycles should be used as the reference index for calculation and analysis.The results provide reference for the construction of earthen structures and prevention of frost damage for graphite tailings in seasonal freezing area of China.