超声波衰减法测量应力的理论与实验研究

THEORETICAL AND EXPERIMENTAL RESEARCH OF STRESS MEASUREMENT BY MEANS OF ULTRASONIC WAVE ATTENUATION METHOD

从理论上和实验上探讨了用波衰减法测量应力的可行性。理论研究表明,对于多种岩石,衰减系数比可以表示成主应力的二次多项式的关系。结合弹性与统计理论,作者建立了钻孔超声波衰减法测量应力的理论模型,并预测了钻孔附近的主应力的大小和方向。实验研究分为两部分:岩芯试件在单轴压应力作用下的声波衰减与应力间关系的标定实验,以及带有水平钴孔的砂岩、石灰岩和花岗岩立方试块在外加单轴或双轴压应力作用下的钴孔衰减测量实验。实验中仅用纵波。实验结果表明,用波衰减法测量深部岩体的原岩应力是可行的。

The feasibility of using the ultrasonic wave attenuation method for measuring stresses was examined theoretically and experimentally.The theoretical analyses showed that for a given rock type the relation between stress and attenuation coefficient ratio could be expressed approximately by second order polynomials.Combining the elastic and statistical theories,the authors set up a theoretical model for stress measurement by using the ultrasonic wave attenuation method,and predicted the magnitudes and directions of the existing principal stresses around the boreholc.The experimental study consists of the following: the attenuation measurements in core specimens under uniaxial stress and the attenuation measurements in boreholes drilled through blocks of sandstone,limestone, and granite subjected to cxtcrnally applied uniaxial or biaxial compressional stresses. In the experiments,only longitudinal wave is used.The results demonstrate that it is feasible to measure the stresses of virgin rocks at the depth of rock by using the ultrasonic wave attenuation method.