岩芯卸荷扰动的声学敏感性试验研究

Experimental Study on Acoustic Responsiveness to Rock Core Unloading Disturbance

国内外学者广泛认为原位岩体的纵波波速小于其中岩块的波速,且岩体愈破碎小得愈多。这是将岩体与岩块纵波波速比的平方定义为岩体的完整性系数并写入现行规范的认识基础。然而在部分工程围岩声波测试中却发现,用通常手段得到的大部分岩体的测井波速反而大于岩芯波速。本文围绕声波速度、岩性、坚硬程度、裂隙特征、胶结程度、完整程度、地应力情况对某地铁隧道工程基岩20余个钻孔150余块岩芯进行多种手段的对比研究和综合分析,探讨了岩芯卸荷扰动的声学敏感性及其影响因素。

It is generally believed that the P-wave velocity of in-situ rock mass is lower than that of relevant rock block, and the more broken the rock mass is, the lower its P-wave velocity is than that of rock block. This is the base of knowing the concept that the square of the ratio of longitudinal wave （P-wave） velocity of rock mass to that of rock block is defined as intactness index of rock mass. However, in the ultrasonic testing of the partial wall rock, it is surprised to find that most P-wave velocities of rock mass obtained by common method are higher than that of the rock block. The paper presents the different contrastive studies and comprehensive analyses of over 20 boreholes and 150 rock cores in the bed rock of a tunnel project in the underground railway from different aspects such as the acoustic velocity, lithology, hardness, cranny feature, etc., and studies the acoustic responsiveness of the rock core unloading disturbance and its causes.