两条断续预制裂纹粗晶大理岩强度参数的研究

STUDY ON THE STRENGTH PARAMETERS OF COARSE MARBLE WITH TWO PRE-EXISTING CRACKS

基于在岩石力学伺服试验机上得到的两条断续预制裂纹粗晶大理岩常规三轴压缩试验结果,采用Coulomb和Hoek-Brown强度准则,获得了断续预制裂纹粗晶大理岩的强度参数,评价了Coulomb和Hoek-Brown准则用于断续预制裂纹岩样强度分析的适用性。研究表明:完整岩样强度和围压之间的关系用Coulomb和Hoek-Brown准则均可以很好地表征,而断续预制裂纹岩样强度更好地符合Hoek-Brown强度准则。利用Hoek-Brown准则确定的粘聚力和内摩擦角也可以表征岩石材料真实的力学特性。断续预制裂纹岩样强度对围压的敏感程度高于完整岩样,计算得到的粘聚力显著低于完整岩样,而内摩擦角高于完整岩样。断续预制裂纹岩样的粘聚力以及内摩擦角与裂纹倾角关系复杂,单轴压缩强度是否参与回归影响较大。由Hoek-Brown准则得到的粗晶大理岩强度参数T(m,s)(联合回归均值)对完整岩样和断续预制裂纹岩样分别为T(6.542,0.99)和T(6.625,0.156),可知断续预制裂纹对岩石强度参数m(软硬程度)影响不大,而对参数s(破碎程度)存在较大影响。

Based on the experimental results of marble with two pre-existing cracks under conventional triaxial compression by the rock mechanics servo-controlled testing machine, the strength parameters of coarse marble with two pre-existing cracks are obtained by adopting the Coulomb criterion and Hoek-Brown strength criterion. The applicability of Coulomb criterion and Hoek-Brown criterion for coarse marble with pre-existing cracks is evaluated. It is indicated that the strength of intact marbles is good accorded with the Coulomb criterion or Hoek-Brown strength criterion. However, the strength of marbles with pre-existing cracks is better accorded with the Hoek-Brown strength criterion. The determined cohesion and internal friction angle of rock in accordance with Hoek-Brown strength criterion can show the mechanical property of rock material. The sensitivity of the strength of marble with pre-existing cracks on the confining pressure is higher than that of intact marble, and the obtained cohesion of marble with pre-existing cracks is distinctly lower than that of intact marble, but the internal fi-iction angle is higher than that of intact marble. For the rock specimen with pre-existing cracks, the cohesion and internal friction angle have a complex relation with the crack angle; even more there exists a close relation with whether or not the uniaxial compressive strength is regressed on the strength analysis. In accordance with the Hock-Brown criterion, the strength parameter T（m, s） （the average value by the combined regression） of coarse marble is T（6.542,0.99） for intact marble, and T（6.625,0.156） for marble with pre-existing cracks. Therefore, for the marble with the same crystal size, the strength parameter m （the extent of soft and hard） has no difference, but the parameter s （the extent of fracture） has great difference.