为研究轴向应力对大长径比砂岩中应力波传播特性的影响,利用动静组合加载试验装置,对砂岩进行了小扰动冲击试验,研究了轴向应力对砂岩中应力波波形、纵波波速、应力波幅值衰减规律的影响。研究表明:同一轴向应力下,不同测点的应力波波形变化不大,而轴向应力的改变对应力波波形变化影响较大;存在轴向应力时,应力波中同时出现压缩波和拉伸波,且轴向应力越大,拉伸波越长;轴向应力对纵波波速变化影响较大,波速与轴向应力呈线性变化,而与传播距离呈指数函数衰减;轴向应力对幅值变化有明显影响,随着传播距离增加,应力波起跳时间点逐渐滞后,应力波幅值呈不同程度的衰减,这与波携带的能量被砂岩中孔隙吸收程度有关。结果表明轴向应力通过改变砂岩密度进而影响了应力波传播特性。
Abstract
To study the influence of static stress on propagation characteristics of stress wave in sandstone with large length-diameter ratio, impact test of small disturbance is conducted by dynamic and static combined testing system. The variation of stress wave, P-wave velocity and stress wave amplitude attenuation under different static stresses are obtained. Research results imply that stress wave curves of different test points remain approximately the same when static stress is constant; stress wave curves vary remarkably when static stress changes. Compressional wave and tensile wave both exist in the presence of static stress, and tensile wave increases with the increase of static stress. In addition, static stress has a great impact on P-wave velocity in a linear relationship, and P-wave velocity decays exponentially with propagation distance. Moreover, static stress also has obvious influence on stress wave amplitude. With the increase of propagation distance, the jump of stress wave delays gradually and stress wave amplitude tends to attenuate as wave energy is absorbed by sandstone fractures. The results suggest that static stress affects stress wave propagation in sandstone by changing the internal pores or fractures of sandstone.
关键词
砂岩 /
轴向应力 /
应力波 /
纵波波速 /
传播特性 /
幅值衰减
Key words
sandstone /
axial static stress /
stress wave /
P-wave velocity /
propagation feature /
amplitude attenuation
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基金
国家自然科学基金项目(51578447, 51664017); 2017年贺州学院(自然科学类)科研项目(2017ZZZK04)
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