岩石超声谐波特征及其随应力的变化  

Ultrasonic harmonic characteristic in rock and its variation with stress

作　　者：郭志伟[1] 葛洪魁 谢凡[1] 张金伟[1] 刘政一[1] 

机构地区：[1]中国地震局地球物理研究所地震观测与地球物理成像重点实验室,北京100081 [2]中国石油大学非常规天然气研究院,北京102249

出　　处：《中国石油大学学报（自然科学版）》2013年第3期50-56,共7页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(41174040);中央级公益性科研院所基本科研业务费专项(DQJB11B11;DQJB11C04);中国石油大学(北京)引进人才科研启动基金项目(YJRC-2012-03)

摘　　要：岩石具有较强的非均质性和强衰减特性,谐波测量的难度较大。建立超声谐波测试实验系统,采用单频脉冲串(tone burst)激发、门控放大、脉冲反转和叠加等增强二次及高次谐波,研究岩石超声谐波的发育与振幅特征,定义名义非线性系数,分析单轴应力下岩石超声谐波及名义非线性系数随应力的变化。结果表明,超声谐波包含了丰富的岩石内部结构信息,表征了岩石的非线性特性,利用先进的仪器系统,采用谐波强化技术,可有效地获得岩石的超声谐波及其振幅,进行岩石非线性特性、微结构变化与损伤演化的监测。The strong heterogeneity and strong attenuation in rocks make ultrasonic harmonic measurement more difficult. An experimental system for observing the ultrasonic harmonic was established. The measurement resolution of high harmonic waves was improved through the tone burst excitation, high power gated amplifier, pulse inversion technique and stacks of many repeated measurements. The growth and intensity of uhrasonic harmonic waves were discussed, the nominal nonlinear coefficient was defined, and the variations of harmonic characteristics and the nominal nonlinear coefficient with stress in rocks were investigated. The results show that ultrasonic harmonic includes the abundant information on rock internal struc- ture, and represents the nonlinearity of the rocks. By the advanced instruments and harmonic reinforcement techniques, ul- trasonic harmonic and its amplititude can be effectively measured, and the damage evolution and the variations of nonlinearity and microstructure in loaded rocks can be monitored.

关 键 词：地球物理学 岩石物理 岩石特性 超声谐波 应力 非线性系数 脉冲反转 

分 类 号：P313.1[天文地球—固体地球物理学]