摘要 在单轴阶段加载条件下，对取自闽南地区的闪长岩岩样进行了不同方向上纵波传播速度的测试.首先根据实验结果总结出不同方向波速在岩石破裂过程中的变化规律，然后基于应力微小变化范围内波速与应力遵循线性关系的假设构建波速-应力关系模型，最后通过多参数分段拟合方式求解模型待定系数.研究结果表明:平行于加载方向的波速在压密阶段快速上升，岩石破裂前的波速降不明显.而垂直于荷载方向的波速在压密阶段少量上升后在临近岩石破裂出现非常明显的波速降.波速-应力关系模型通过参数的变化可以准确地描述不同方向波速的变化过程，证明了模型的适用性.Abstract：Under uniaxial multi-level loading condition， the longitudinal wave velocities in different directions from south Fujian diorite were measured.Firstly， based on the experiment results， the changes of wave velocities with stress were analyzed. And then according to the hypothesis of the linear relationship between wave velocity and stress in a very small range of stress， a wave velocity-stress model was built.In the end， using the multi-parameter piecewise fitting， undetermined coefficients in the model were determined. The results showed that the variation of wave velocity paralleled to the loading direction is characterized by an initial instant and nonlinear rise below a critical stress， followed by a more gradual linear increase above this critical stress， and the decrease is not obvious before the failure. Whereas， the variation of wave velocity perpendicular to the loading direction is characterized by a slightly rise below a critical stress， followed by an accelerated decrease above this critical stress， and the decrease is very obvious before the failure. The variation of wave velocities in different directions can be accurately fitted by the wave velocity-stress model， which confirms the applicability of the model.
References
[1]
Wyllie M R J，Gregory A R，Gardner G H F.An experimental investigation of factors affecting elastic wave velocities in porous media［J］.Geophysics，1958，23(3):459-493.
[2]
Sharma P.Geophysical methods in geology［M］.New York:Elsevier，1986.
[3]
施行觉，赵闯，杨映希，等.岩石临破裂前波速变化特征的实验研究［J］.地球物理学报，2012，55(10):3386-3392.(Shi Xing-jue，Zhao Chuang，Yang Ying-xi，et al.Experimental study of velocity characteristic before rock fracture ［J］.Chinese Journal of Geophysics，2012，55(10):3386-3392.)
[4]
宋丽莉，葛洪魁，梁天成，等.小应力扰动下岩石弹性波速变化的波形检测［J］.中国石油大学学报:自然科学版，2012，36(4):60-65.(Song Li-li，Ge Hong-kui，Liang Tian-cheng，et al.Waveform detection of elastic wave velocity changes in rock under small stress perturbations［J］.Journal of China University of Petroleum:Natural Science，2012，36(4):60-65.)
[5]
Fortin J，Stanchits S，Dresen G.Acoustic emission and velocities associated with the formation of compaction bands in sandstone［J］.Journal of Geophysical Research，2006，111:B10203-B10209.
[6]
Martin C D，Christiansson R，Soderhall J.Rock stability considerations for siting and constructing a KBS-3 repository［R］.Stockholm:Swedish Nuclear Fuel and Waste Management Co，2001.
[7]
Ullemeyer K，Nikolayev D I，Christensen N I，et al.Evaluation of intrinsic velocity-pressure trends from low-pressure P-wave velocity measurements in rocks containing microcracks［J］.Geophysical Journal International，2011，185(3):1312-1320.
[8]
巩思园，窦林名，何 江，等.深部冲击倾向煤岩循环加卸载的纵波波速与应力关系试验研究［J］.岩土力学，2012，33(1):41-47.(Gong Si-yuan，Dou Lin-ming，He Jiang，et al.Study of correlation between stress and longitudinal wave velocity for deep burst tendency coal and rock samples in uniaxial cyclic loading and unloading experiment［J］.Rock and Soil Mechanics，2012，33(1):41-47.)
[9]
Yin H Z，Nur A.Stress-induced ultrasonic velocity and attenuation anisotropy of rocks［J］.SEG Expanded Abstracts，1992，11(1):1073-1076.
[10]
Kim H，Cho J W，Song I.Anisotropy of elastic moduli，P-wave velocities，and thermal conductivities of Asan Gneiss，Boryeong Shale，and Yeoncheon Schist in Korea［J］.Engineering Geology，2012，147:68-77.一位数()
