饱水对致密岩石声学参数影响的试验研究  

ACOUSTIC PARAMETERS OF LOW-POROSITY ROCK UNDER DRY AND SATURATED CONDITIONS

作　　者：朱合华[1] 周治国[1] 邓涛[1] 

机构地区：[1]同济大学地下建筑与工程系

出　　处：《岩石力学与工程学报》2005年第5期823-828,共6页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(40172095);西南能矿资源开发及环境灾害控制工程资助项目

摘　　要：通过纵、横波透射测试得到了岩石内部结构的一些信息,对致密板岩、花岗片麻岩、黑云母片麻岩的声学参数进行了研究。对岩石岩样声波运动和动力参数的分析发现:(1) 上述三种岩石吸水率均较低,一般为0.05%～0.2%。其纵波波速受水的影响较小,饱水后花岗片麻岩、黑云母片麻岩纵波波速略有提高,提高幅度为1.35%～1.97%,板岩纵波波速略有降低,变化小于0.95%;而对于这三种岩石横波速度提高0.22%～1.61%。(2) 板岩、黑云母片麻岩等区域变质岩的波速各向异性特征明显,而花岗片麻岩波速不存在明显的各向异性特征。饱水对区域变质岩的波速各向异性略有强化,而对花岗片麻岩影响很小。(3) 饱水后,从上述三种岩石接收到的纵波波谱都发生了变化,纵波主频明显降低,表现为对波谱中高频成分滤波作用的增强。在饱水和烘干状态下,岩石的滤波作用都表现出了明显的各向异性,这反映出岩石不同方向上的微观结构存在差异。A testing study is presented on propagation characteristics of P wave and S wave in rock samples under dry and water-saturated conditions. The samples, including slate, biotite gneiss and granite gneiss, are all low-porosity rocks with water absorption of only 0.05%-0.2%. The acoustic parameters of rock samples under dry and water-saturated conditions are tested with ultrasonic method. Much useful information about the inner structure of these rock samples is learned from P wave and S wave. P wave velocity in water-saturated granite gneisses and biotite gneiss becomes a little higher than that of the dry ones only by 1.35%-1.97%, but becomes lower in water-saturated slates by less than 0.95%. S wave velocity in three types of rocks becomes a little higher than that of dry ones by 0.22%-1.61%. The anisotropy of waves (P wave and S wave) velocity in slate and biotite gneiss is observed which is strengthened by water saturation, however, such phenomenon has not been found in granite gneiss. The dominant frequency of P waves becomes lower when rock samples get water-saturated, which means the high frequency part is filtered. All rock samples present obvious anisotropy of dominant frequency.

关 键 词：岩石力学 致密岩石 声学参数 饱水 各向异性 

分 类 号：TU459.3[建筑科学—岩土工程]