完整岩体对测井频率应力波的滤波特性

发布时间：2018-02-27 01:10

本文关键词： 完整岩体滤波特性 Maxwell模型应力波衰减系数　出处：《振动与冲击》2014年23期 　论文类型：期刊论文

【摘要】：不同频率范围内的应力波在岩体的传播过程中,衰减系数对频率的依赖性具有显著差异。通过现场试验研究完整岩体对测井频率范围内应力波的滤波特性,针对常用黏弹性模型在描述衰减系数与频率关系存在不足,在频域上对黏性系数进行非定常处理,建立黏性系数非定常Maxwell模型,采用波形相关系数评价改进模型的滤波效果。研究结果表明,完整岩体总体上表现为低通滤波,在低通滤波范围内具有非等间距带通滤波特性,随传播距离增加,带通数逐渐减小;在吸收频率过渡带,应力波衰减系数随频率变化非常快,黏性系数非定常Maxwell模型能够有效描述应力波在完整岩体中的衰减系数变化规律;吸收频率过渡带的边界频率与传播距离成负指数关系,吸收频率过渡带的陡度参数可以近似认为是常数;随传播距离增加,黏性系数非定常Maxwell模型描述完整岩体的滤波效果明显提高,当传播距离为4.75m时,波形相关系数达到0.89,表明采用改进模型描述完整岩体是有效的。
[Abstract]:During the propagation of stress waves in different frequency ranges, the dependence of attenuation coefficient on frequency is significantly different. The filtering characteristics of stress waves in logging frequency range are studied by field tests. Aiming at the deficiency of the common viscoelastic model in describing the relationship between attenuation coefficient and frequency, the unsteady treatment of viscosity coefficient in frequency domain is carried out, and the unsteady Maxwell model of viscosity coefficient is established. The waveform correlation coefficient is used to evaluate the filtering effect of the improved model. The results show that the whole rock mass is characterized by low-pass filtering, and has the characteristics of non-equidistant band-pass filtering in the range of low-pass filtering, and increases with the propagation distance. In the transition zone of absorption frequency, the attenuation coefficient of stress wave changes very quickly with frequency, and the unsteady Maxwell model of viscosity coefficient can effectively describe the variation of attenuation coefficient of stress wave in intact rock mass. The boundary frequency of the absorption frequency transition zone has a negative exponential relationship with the propagation distance. The steepness parameter of the absorption frequency transition zone can be approximately considered as a constant, and increases with the propagation distance. The filtering effect of the unsteady Maxwell model for describing the intact rock mass is obviously improved. When the propagation distance is 4.75 m, the correlation coefficient of the waveform is 0.89, which indicates that it is effective to use the improved model to describe the intact rock mass.
【作者单位】：江西理工大学;中国地质大学;
【基金】：国家自然科学基金资助项目(51104069) 江西省自然科学基金项目(2010GQC0067) 江西省教育厅科技项目(GJJ12339,GJJ11130)
【分类号】：TU452

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