单裂隙岩体冻融力学特性试验分析

Experimental Analysis on Mechanical Characteristic of Single Cracked Rock Mass under Freeze-Thaw Condition

采用具有不同几何特征的闭合裂隙类砂岩模型试样,进行冻融后的单轴压缩试验,分析裂隙岩体经不同冻融循环次数后的物理力学特性,以及不同裂隙倾角、不同裂隙长度的岩样对冻融岩体强度及破坏形态的影响。研究发现:预制闭合裂隙对冻融岩样外观破坏特征影响不是很大;同一类岩样在其它条件相同的条件下,单轴抗压强度及弹性模量随着冻融次数的增加而减小,相同的冻融次数,相同裂隙倾角不同裂隙长度的试件,随着裂隙长度的增长,单轴抗压强度有较大幅度降低,且随着裂隙倾角的增大,降低的程度越来越小;而对于相同的冻融次数,相同裂隙长度不同裂隙倾角的试件,倾角的变化对冻融岩样的影响不大;冻融岩样单轴试验破坏形态随着冻融次数的增加,由单一的较平滑的破坏面逐渐发展为多个表面粗糙的破裂面,除完整岩样及倾角为90°的岩样为劈裂破坏外,其余裂隙岩样基本为沿裂隙面的剪切破坏。

Physical and mechanical properties for crack closed rock mass were studied after different freeze-thaw cycles, using rocklike material to produce seven kinds of specimens with different geometric characteristics, through uniaxial compression test, the influence on different fissure inclination and fissure length to the rock mass strength were studied. The study found that： preexisted closed cracks have little impact on appearance characteristics of freeze-thaw rock samples ; the uniaxial compressive strength decreases badly with the number of freeze-thaw cycles, as well as elastic modulus; under the same freeze-thaw cycles and fissure inclination, with the growth of the cracks length, the uniaxial compressive strength declines seriously, in the case of other conditions are the same , the inclination has little effect on the uniaxial compressive strength ; Failure pattern of rock samples under uniaxial compression test has undergone the changes from a single smooth failure surface gradually to multiple rough fracture surfaces with the number of freeze-thaw cycles increases, in addition to the samples with fissure angle of 90 degree and intact sam- pies, whose failure mode is splitting failure, the rest of the cracked rock samples generate shear failure.