含裂隙岩石的受压破坏机理研究

LABORATORY TESTS ON FAILURE MECHANISM OF FRACTURED ROCK UNDER COMPRESSION

含裂隙结构面岩体在加载过程中的裂纹扩张和强度对研究岩体的变形破坏机理具有重要意义。用砂浆裂隙试件模拟含裂隙岩石进行单轴压缩实验,获得了3种倾角(45°、60°、75°)和3种裂隙长度(45mm、60mm、75mm)的9种组合工况的裂隙扩展角度和初裂强度,并分析了9种工况下的受压破坏机理。实验结果表明:当裂隙长度相同时,初裂强度随倾角的增加而增加,且倾角由60°增加到75°,初裂强度增加得更快;当裂隙倾角一定时,初裂强度随裂隙长度的增加而降低。应用最大周向正应力理论分析了含裂隙试件的受压破坏机理,获得了裂隙扩展角理论表达式;通过比较可知:裂隙扩展角的实测值和理论值基本吻合。

The crack propagation and strength of fissured rocks under applying loads are significant for the study of rock deformation mechanism. Mortar fractured specimens have been simulated as fissured rock in the uniaxial compression experiment. Different crack length,the initial propagation angle of specimens and initial crack strength have been obtained by setting 9 experimental conditions. They have 3angles of 45°,60° and 75° and 3 crack length of 45 mm,60mm and 75 mm. The compression failure mechanism is also analyzed. The results show the following.When the crack length is the same,the initial crack strength is increased by the increase of angles. When the angle is increased from 60°to 75°,the initial crack strength is increased faster. When the crack angle stays at a certain level,the initial crack strength is decreased by the increase of the crack length. By employing the theory of maximum circumferential stress,the failure mechanism of fractured specimens under compression is interpreted.Theoretical expression of crack propagation angle is acquired. By comparison,it is found that the measured and theoretical values of crack propagation angle are in good agreement.