川东北砂岩单三轴压缩过程中应力-波速变化规律的试验研究

Experimental Study on the Change Law between Stress and Velocity of Longitudinal Wave for the Sandstone from Northeastern Sichuan in Uniaxial and Triaxial Compression

为能够利用声波测井资料对岩石的力学参数进行反演,选取代表性埋深砂岩,对单三轴压缩过程中的应力-纵波波速之间的变化规律进行了研究,对不同围压下,压缩过程中的波速变化规律进行了比较。结果表明,在轴向压缩过程中,砂岩纵波波速显著增加,砂岩单轴抗压强度与纵波波速之间存在一定关系。砂岩压缩过程中,在低围压下波速变化相对明显;高围压下波速变化相对较小,在偏应力较小时,波速与应力基本为线性关系,当偏应力达到一定数值时,波速稳定在某一定值,即曲线出现水平渐近线。

In order to inverse mechanics parameters of the rock based on sonic logging data,the change-laws between stress and the velocity of longitudinal wave for the representative sandstones selected in different depth during uniaxial and triaxial compression were studied. The change laws of the wave velocity under different confining pressure were compared. The results showed that in the axial compression the velocity of longitudinal wave in the sandstone increase rapidly, there are some relationships between the uniaxial compressive strength and the longitudinal wave velocity, the velocity of longitudinal wave change remarkably under the low confining pressure, and the velocity of longitudinal wave change little under the high confining pressure. The velocity of longitudinal wave and the stress will be linear relation when the deviatoric stress is small, and when the deviatoric stress reach to a certain value, the velocity of longitudinal wave keeps at a steady value, the curve change to a horizontal asymptote.