单轴荷载下软砂岩声波传播特性实验研究.docVIP

  单轴荷载下软砂岩声波传播特性实验研究 黎亮1，刘高1,2，罗泽华1** （1. 兰州大学土木工程与力学学院，兰州 730000； 5 10 15 20 25 30 35 40 2. 西部灾害与环境力学教育部重点实验室，兰州 730000） 摘要：本文对新近纪软砂岩进行了单轴力学实验；同时同向地采集了软砂岩单轴压缩全过程 中的声学数据；分析了压缩过程中不同阶段软砂岩声波传播特性与应力、岩石内部裂隙发育 的相关性及其相互作用机理。研究发现：(1) 纵横波波速、振幅、波形和频谱都随应变表现 出阶段性变化特征且与岩石所处的应力-应变阶段相对应。(2) 岩石压密、弹性和裂纹稳定扩 展阶段，纵横波波速曲线微微上凸，与瞬时弹性模量(应力-应变曲线的斜率)变化趋势一致； 而振幅曲线微微下凹，与应力变化趋势一致；声波的这种变化说明波速与瞬时弹性模量具有 良好的对应关系，而振幅与应力具有良好的对应关系。(3) 在裂纹扩展阶段，纵波波速变化 不大，波形规则，而横波波速下降明显，波形也开始变得杂乱。(4)在岩石破坏阶段，纵波 波速的变化与岩石的破坏过程同步，不同的破坏过程对应不同波速变化方式。(5) 纵波有多 个频域，各频域分布随应力增加变化不大，但各频域的能量的相对大小变化剧烈；横波在破 坏之前主频域分布基本不变，而破坏阶段主频域杂乱明显。本次研究发现的单轴荷载下软砂 岩的声波传播特性规律和变化特征可以为软砂岩稳定性评价和内部裂隙演化的原位快速勘 察提供参考与借鉴。 关键词：软砂岩；波速；振幅；波形；频谱 中图分类号：TU45 The Experimental Research on Acoustic Wave Propagation Characteristics of Soft Sand under Uniaxial Load LI Liang1, LIU Gao1,2, LUO Zehua1 (1. School of Civil Engineering and Mechanics,Lanzhou University, Lanzhou 730000; 2. Key Laboratory of Mechanics on Disaster and Environment in Western China, The Ministry of Education of China, Lanzhou 730000) Abstract: We conducted a series of mechanical tests and acoustic measures on Neogene soft sand in order to analysis the diversity of acoustic wave propagation characteristics at different stages. We found that：(1) Velocity, amplitude of the first arriving waves,waveforms,frequency spectrum change with soft sand deformation and relate to the corresponding stages of rock; (2) At the compression and elastic stages of soft sand, the changing trend of longitudinal and transverse wave velocity is consistent with the instantaneous elastic modulus(gradient of the stress-strain curve); while amplitude is consistent with stress; (3) At crack propagation stage, longitudinal wave velocity show weak variation and waves are regular; while transverse wave velocity reduced obviously and waves become irregular gradually; (4) At the failure stage, longitudinal wave velocity changes with the corresponding rock failure process and different failure process results in defferent change w