含天然贯通弱面石灰岩试样的力学性质研究

 为研究天然弱面对岩石力学特性的影响，对40个完整和含有53°～90°倾角的天然贯通弱面石灰岩试样进行纵波速度测试、单轴和常规三轴压缩试验。试验结果表明：纵波速度与弱面倾角和单轴抗压强度并没有明确的关系。试样破坏有沿弱面滑移、穿切弱面和复合破坏3种形式：弱面倾角为65°～80°时易沿弱面滑移破坏，强度明显偏低；弱面倾角小于65°或大于80°时出现穿切弱面破坏，强度和破裂角大致满足Coulomb 强度准则；有2个试样发生复合破坏，强度介于两者之间。石灰岩充填弱面的材料与主体类似，因而与完整试样具有相同的内摩擦因数 0.944；据此可以从三轴压缩强度扣除围压影响，得到40个试样材料强度为30.3～177.1 MPa，平均值为121.3 MPa，标准差为32.6 MPa，大致服从正态分布规律。因最弱断面的方向随试样而不同，其黏聚力也存在显著差异，引起试样三轴压缩的强度和破坏方式的显著不同。

STUDY OF MECHANICAL PROPERTY OF LIMESTONE SPECIMENS WITH NATURAL CONTINUOUS WEAK PLANE

In order to study the effect of natural weak plane on mechanical properties of rock，40 limestone intact specimens and specimens with the angle of natural continuous weak plane ranged from 53° to 90° are carried out longitudinal wave velocities，uniaxial and pseudo-triaxial compression. The tests indicate that：longitudinal wave velocities，dip of specimens with weak plane，and uniaxial compressive strength have no certain relationship. Failure modes of specimens have three types，sliding-failure along the weak plane，shearing-failure across the weak plane and comprehensive failure，when the angle of specimen with weak plane ranged from 65° to 80°，it takes place sliding-failure along the weak plane，its strength is obviously lower，when the angle of specimen with weak plane is less than 65° or greater than 80°，it takes place shearing-failure across the weak plane，the strength and the fracture angle approximately meet Coulomb strength criterion；Two specimens take comprehensive failure，the strength of comprehensive failure is between shearing-failure across the weak plane and sliding-failure along the weak plane. The filling material of weak plane of limestone is approximately to main body，which has same internal friction coefficient 0.944 with intact specimens. The material strength of 40 specimens that the strength of triaxial compression deducts confining pressure is between 30.3 and 177.1 MPa，the average is 121.3 MPa，the standard deviation is 32.6 MPa，which roughly conform to normal distribution；The orientation of the weakest plane of rock varies with specimen whose cohesion is significant difference，which makes significant different the strength and failure modes of triaxial compression.