各向异性岩体弹性矩阵系数反演分析与应用

Inversion technique and engineering application of elastic matrix coefficients for anisotropic rock mass

国内外尚未见各向异性岩体弹性矩阵21个系数反演分析的研究成果。采用"横波可控震源激振VSP三维三分量数据采集"岩体原位测试技术,设计矿山岩体精细勘探WalkawayVSP观测系统,利用基于各向异性介质Christoffel方程解的qP波及q S波慢度矢量、偏振矢量计算公式,以原位采集的直达qP波及qS波的波场参数(慢度矢量、偏振矢量)为输入条件,纵横波联合反演出完全各向异性条件下岩体介质弹性矩阵的21个系数。利用弹性矩阵系数,识别出覆岩"三带"各向异性为HTI介质属性,计算出不同深度岩体的各向异性参数及工程力学参数,对比分析覆岩"三带"与各向异性参数、工程力学参数之间的关系。研究成果使岩体力学及勘探地震学正演计算不再依赖目标介质各向异性类型,开辟岩体工程力学特性研究的新方向。

There are seldom inverse researches of 21 elastic matrix coefficients of anisotropic rock mass at home and abroad.In this paper,the Walkaway VSP observation system for fine exploration of mine rock mass is designed by using the rock mass in-situ testing technology of“three-dimensional three component data acquisition of VSP excited by shear wave vibrator”.By using the formulas for calculating the slowness and polarization vectors of qP and qS waves based on the solution of Christoffel equation in anisotropic media,and taking the wave field parameters(slowness and polarization vectors)of qP and qS waves collected in situ as input conditions,the 21 coefficients of the elastic matrix of rock mass under the condition of complete anisotropy are obtained based on the combination of vertical and horizontal waves.Using the elastic matrix coefficients,the“three zones”anisotropy of the overlying rock is identified as HTI medium attribute,and the anisotropy parameters and engineering mechanical parameters of rock masses at different depths are calculated.The relationships between the“three zones”of overburden with the anisotropy parameters and the engineering mechanical parameters are analyzed.The results of this study make the forward calculation of rock mechanics and exploration seismology no longer depend on the assumption of the type of anisotropy of the target medium,and open up a new direction for the study of rock engineering mechanical properties.