力学学报  2019 , 51 (3): 949-960 https://doi.org/10.6052/0459-1879-18-328

生物、工程及交叉力学

白云岩受压声学特性及其在裂缝研究中的应用1)

朱洪林*, 陈乔*2), 徐小虎**, 刘洪††, 文翔宇***, 陈吉龙*, 彭伟†††, 赵彬凌***

* 中国科学院重庆绿色智能技术研究院,重庆 400714
† 西南石油大学油气藏地质及开发工程国家重点实验室,成都 610500
** 中石油煤层气有限责任公司,北京 130022
†† 重庆地质矿产研究院,重庆 401123
*** 中国石油西南油气田公司,成都 610051
††† 中国石油西南油气田公司蜀南气矿,四川泸州 646001

THE ACOUSTIC CHARACTERISTICS OF DOLOMITE UNDER COMPRESSION AND ITS APPLICATION IN THE CRACK RESEARCH1)

Zhu Honglin*, Chen Qiao*2), Xu Xiaohu**, Liu Hong††, Wen Xiangyu***, Chen Jilong*, Peng Wei†††, Zhao Binling***

* Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
† State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University, Chengdu 610500, China
** PetroChina Coalbed Methane Co Ltd, Beijing 130022, China
†† Chongqing Institute of Geology and Mineral Resources, Chongqing 401123, China
*** PetroChina Southwest Oil & Gas field Company, Chengdu 610051, China
††† Shu'nan Gas Mine,PetroChina Southwest Oil & Gas field Company, Luzhou 646001, Sichuan,China

中图分类号:  TE311

文献标识码:  A

通讯作者:  2) 陈乔,副研究员,主要从事声波、岩石力学与工程地质相关研究. E-mail: chenqiao@cigit.ac.cn

收稿日期: 2018-10-9

网络出版日期:  2019-05-18

版权声明:  2019 力学学报期刊社 所有

基金资助:  1) 国家自然科学基金项目(41502287),重庆市自然科学基金项目(cstc2018jcyjAX0670,cstc2015jcyBX0120),重庆市国土局科技计划 项目(CQGT-KJ-2017026,CQGT-KJ-2014037),重庆市技术创新与应用示范重点研发项目(cstc2018jscx-mszdX0074)和重庆市社会事业与民生保障科技创新专项(cstc2017shmsA120001)资助.

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摘要

通过实验手段研究了白云岩在三轴和单轴加载过程中的声波波速、幅度、频谱特性的变化特征. 结果发现:(1)白云岩在受压变形过程中,声波波速的变化较好地反映了岩石内部裂缝的闭合、产生、扩展和贯穿等变化. 总体而言,横波波速比纵波能更好地预测裂缝的产生,而纵波对裂缝的非稳定发展或贯穿有较敏感的反映. (2)随着轴压的增大,纵、横波波形的末端都有散射波的出现,且横波波形末端的"鱼尾"状散射波信号更为明显(此时应力点为极限强度的60%左右),预示着岩石内部裂缝的产生和稳定扩展. (3)频谱曲线也很好地反映了岩石内部结构变形情况. 随着岩石受力的增大,频谱曲线上的振幅都呈现增大趋势,标志着岩石的压实阶段;当频谱曲线上低频段较高频段活跃时,标志着裂缝的产生;更有甚者,低频还会取代高频成为主频. (4)在岩石受压裂缝闭合阶段,首波振幅和频谱主振幅都呈现上升趋势;而在裂缝不稳定扩展阶段,主振幅表现出比首波振幅低的上升趋势;振幅曲线达到峰值后都存在一突降拐点,预示着岩石的贯通破坏. 研究对于地层岩石的动态长期监测和工程岩体的稳定性评价都具有重要的理论参考价值.

关键词: 白云岩 ; 受压 ; 裂缝 ; 声波速度 ; 频谱特征 ; 振幅

Abstract

The variation characteristics of acoustic velocity, amplitude and spectral characteristics of dolomite under triaxial and uniaxial loading are studied by means of the experimental method. The following conclusions can be drawn. (1) During the process of compression deformation of the dolomite, the change of acoustic wave velocity well reflects the closure, generation, expansion and penetration of cracks in the rock. In general, the shear acoustic wave velocity is better than the longitudinal acoustis wave to predict the generation of cracks, while the longitudinal acoustic wave has a more sensitive reflection on the unstable expansion of the cracks. (2) With the axial load increases, the scattered wave signal appears at the end of the longitudinal acoustic wave and transverse wave pattern. And the "fishtail" scattered wave signal at the end of the shear waveform is more obvious (at this point, the axial stress reaches 60% of the limit strength), which indicates the generation and stability expansion of the crack in the rock. (3) The spectral curve is also a good reflection to the deformation of the internal structure in the dolomite rock. As the axial load increases, the amplitude of the spectrum curve shows an increasing trend, which indicates the compaction stage of the rock; when the low frequency signal is more active than the high frequency one in frequency spectrum curve, it marks the occurrence of the crack; what is more, low frequency will replace the high frequency to become the main frequency. (4) In the stage of crack closure, both the first arrival wave amplitude and the principal amplitude tend to increase; while in the stage of unsteady expansion of the crack, the principal amplitude tends to increase more slowly than the first arrival wave amplitude; after the amplitude curve reaches the peak there is a sudden drop point, which indicates the destruction of the rock. The variable characteristic of acoustic propagation displayed during the process of rock pressed makes a good sense to the prediction of rock crack and the evaluation of rock stability. This study has important theoretical reference value for the dynamic long-term monitoring to the rock deformation and the stability evaluation of engineering rock mass.

Keywords: dolomite ; under compression ; crack ; acoustic velocity ; frequency spectrum characteristics ; amplitude

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朱洪林, 陈乔, 徐小虎, 刘洪, 文翔宇, 陈吉龙, 彭伟, 赵彬凌. 白云岩受压声学特性及其在裂缝研究中的应用1)[J]. 力学学报, 2019, 51(3): 949-960 https://doi.org/10.6052/0459-1879-18-328

Zhu Honglin, Chen Qiao, Xu Xiaohu, Liu Hong, Wen Xiangyu, Chen Jilong, Peng Wei, Zhao Binling. THE ACOUSTIC CHARACTERISTICS OF DOLOMITE UNDER COMPRESSION AND ITS APPLICATION IN THE CRACK RESEARCH1)[J]. Chinese Journal of Theoretical and Applied Mechanics, 2019, 51(3): 949-960 https://doi.org/10.6052/0459-1879-18-328

引 言

地层岩石长期处于复杂的三向应力环境当中,一旦这种复杂的应力平衡被打破,地层岩石便处于受载状态直至变形破坏. 其破坏过程往往伴随着原裂隙的压密闭合、新裂缝的产生、扩展至贯通破坏,即岩石破坏的本质是由于岩石在外部载荷的作用下引起内部结构发生变化而最终失去承载能力. 地层岩石的这种失稳破坏不仅给采矿和石油工业带来巨大的经济损失,由此引发的地质灾害更是严重威胁人民群众的生命财产安全. 因此,如何有效监测岩石的变形,并及时预测岩石的就地稳定性具有重要的科研价值和工程意义.

通过测量岩石的某些能反映其内部结构变化的物理性质,来间接了解其内部结构的变化是目前广泛采用的一种思路. 声波(从低频声波到高频声波)不仅对各类岩石都有一定的穿透力和分辨力,而且当它透过岩石传播时,便携带了与岩石物理、力学相关的各种信息. 因此,穿过受力状态下岩石的声波信息与岩石内部结构的变化及受力状态有着密切的关系,它是一种理想的信息载体,对岩石受压状态下声学特性的研究将有利于推进超声波测试技术在岩土工程中更深层次的应用. 迄今为止,国内外许多学者在这方面做了大量工作. 就测试技术而言,主要分为两种,即声发射和超声波测试.

岩石损伤及断裂过程中释放的声发射信号,直接反映了材料内部微破裂的活动过程.Rudajev等[1]利用声发射技术探究了岩石在单轴压缩破坏过程中的特征.Thaml等[2]研究了板状岩石在多通道声发射监测系统下拉伸时的特征,并且能够利用二维有限元软件在单轴拉伸的情况下,对声发射特征进行模拟分析.Ganne等[3]对岩石在峰值之前的声发射特征进行了研究,并总结归纳了声发射能量在此过程中累积的4个阶段.裴建良等[4-7]则分别对大理岩、灰岩、煤岩试样进行了加载过程中的声发射监测实验,研究岩样在破坏过程中声发射特征的变化规律,揭示其损伤演化机制.Xie等[8]将声发射技术应用在层状盐岩破坏过程的研究;武晋文等[9]应用声发射技术研究了花岗岩的热破坏过程;曾鹏等[10]通过声发射幅值与频率分布来研究岩石断裂特征和过程;刘建坡等[11]应用声发射时空演化特征研究了预制孔岩石的破坏过程.Kim等[12]同时对花岗岩进行宏观变形和声发射测试,发现声发射能量比宏观变形对裂缝起裂及扩展更加敏感.Zhang等[13]研究了花岗岩、大理岩、盐岩损伤破裂过程中的声发射特征,并对三者的损伤演化趋势进行了对比分析.

超声波测试作为另一种无损检测手段,相比声发射测试受环境影响较小,且测试方法便捷可行,因而在室内试验和现场岩体测试中获得广泛运用.Nur等[14-16]在理论研究方面首次从岩石中微裂缝闭合出发,提出了岩石压密阶段波速随应力呈二次函数关系.Ashraf等 [17]对砂岩中胶结物对波速的影响进行了研究,结果发现,所研究的地层声波波速受孔隙度和胶结物的影响较大,当胶结物为黏土和石英共生时,是导致波速下降的主要原因.尤明庆等[18]研究了大理岩试样三轴压缩和砂岩试样经历不同温度烘烤后的力学特性与纵波速度的关系.刘维国等[19]通过对砂岩进行加温三轴实验,指出横波波速峰值点及其后波速减小现象说明载荷作用下的砂岩产生了新的微裂缝,体积应变最大值点的差应力大于横波波速最大值点的差应力,可以用检测横波波速最大值的办法确定岩石的应力门槛值.陈乔 等[20-21]采用超声波透射法研究了静态条件下页岩层理结构与波速的相关性.King[22]通过实验研究发现真三轴加载下板岩波速与裂缝密度呈线性发展,砂岩呈非线性,主要是由于波速同时受裂缝密度及导向的共同影响.通过相互垂直或更多方向的波速测试可表征岩石的各向异性[23],Chow等[24]发现在岩石循环加卸载中,循环加载次数增加,波速逐渐减小,且波速各向异性的导向也发生变化.波速变化规律也受原始裂缝的影响,Audrey等[25]通过实验发现,随着应力增大,完整岩样轴向波速基本保持稳定,而含裂缝岩样波速先小幅增大,之后持续减小,且减小幅度远小于侧向波速,同时含裂缝试样各向异性大于完整试样,随着偏应力增大,波速各向异性逐渐增大,尤其是含初始微裂缝试样.张国凯等[26-27]基于细观尺度颗粒研究了超声特征与裂缝扩展及损伤演化特征的相关性. 张晓平等[28]提出采用声波波速连续测量方法进行岩石加载过程波速的连续观测,有助于分析裂缝扩展过程中声波波速的变化,研究发现裂缝的产生、扩展和贯通过程中沿垂直裂缝方向声波波速变化最为显著.

综合当前研究现状来看,尽管对岩石声发射理论与应用的研究已取得了不少成果,但这些研究多集中在声发射率、能量等随时间的变化特征方面. 依据声发射对岩石破坏过程的研究大多依靠推测,研究成果不能完全真实地反映岩石在整个受压过程中其内部微裂缝孕育、萌生、扩展及贯通的演化过程. 而岩石宏观波速的变化与裂缝的闭合、新生裂缝的萌生及扩展导向密切相关,因此研究岩石受压作用下不同阶段超声波波速及频谱特性与微裂缝演化过程的对应关系就显得至关重要. 而围绕这一主题目前未见系统性的研究报道,鉴于此,本文以白云岩在受压(单轴和三轴)条件下同步采集纵、横波时差和波形信号的实验为基础,对其岩石力学特征、声波波速、幅度、频谱特性的变化特征展开系统研究,进而对声学特性在岩石裂缝研究中的应用进行理论性的阐述和探讨.

1 实验原理及数据处理方法

实验采用MTS-815三轴岩石力学测试系统完成. 所不同的是,实验机标准的水力压头由承压型声波换能器替换. 换能器纵波激发中心频率为1,000,kHz,横波激发中心频率为500,kHz,测量精度为0.1,$\mu$s. 该换能器轴向工作压力可达420,MPa. 实验过程中,同步采集纵、横波时差及波形. 声波采集使用北京普源精电科技有限公司的DS4000E示波器,示波器与计算机相联,进行波形实时采集. 将实验所选用白云岩切割、打磨制成$\phi$ 25,mm$\times $50,mm的圆柱体试件. 低温烘干处理后采用HKGP-3型孔渗测定仪,测量孔隙度和渗透率. 岩心基本物性参数见表1.

表1   岩心基本物性参数

Table 1   The basic physical parameters of the cores

新窗口打开

表中,波速的研究主要是对所采集的岩样声波信号进行首波时差值的提取.其计算步骤为:以测量某一固定距离$L$之间声传播所需的时间$T$为基础,在考虑电子线路本身的延迟时间$T_{0}$及岩样在岩石力学测试系统内受压破坏过程中,轴向长度要受压发生缩短的前提下,根据所测试样长度计算超声波在不同试件中的传播速度.

$$V=\dfrac{L(1-v)}{T-T_0} (1)$$

式中,$v$为声波(包括纵、横波)波速,km/s; $T$为超声波穿过电子线路及试件的总延迟时间,$T_0$为电子线路本身的延迟时间,$\mu$s;$L$为试件的纵向尺寸,mm;$v$为岩样在受压过程中的轴向应变,%.

根据FFT原理进行频谱分析,利用数据分析软件Origin进行快速傅里叶变换,变换后可得到频率域的振幅谱数据. 频谱分析过程如下:采集各应力点声波波形数据$\to $对波形信号进行FFT 处理$ \to $提取各应力点对应的频谱曲线的主频和主振幅.

2 受压条件下白云岩声波波速及频谱特性分析

2.1 受压条件下的声波纵、横波波速特性分析

16#, 17#, 20#, 21#岩芯受压条件下的声波纵、横波波速随岩石变形而变化的特征分别见图1图2.图中纵波、横波速度分别用$V_{\rm p}$和$V_{s}$表示,$s_{\rm uc}$代表单轴抗压强度,$s_{\rm tc}$代表三轴抗压强度.

图1   高孔渗白云岩纵、横波波速$\!$-$\!$-$\!$应力$\!$-$\!$-$\!$应变双坐标曲线

Fig. 1   Longitudinal and transverse wave velocity-stress-strain bi-coordinate curves of high-porosity dolomite

图2   低孔渗白云岩纵、横波波速$\!$-$\!$-$\!$应力$\!$-$\!$-$\!$应变双坐标曲线

Fig. 2   Longitudinal and transverse wave velocity-stress-strain bi-coordinate curves of low-porosity dolomit

其中,17#岩样为单轴加载,峰值抗压强度23.15,MPa;16#岩样为三轴加载,抗压强度94,MPa.两块岩样均为鲕粒白云岩, 孔隙较发育,孔渗相对较大.对17#岩样,纵波在极限强度的17.27%应力范围内,波速快速上升;当应力达到极限强度的82.9%时,纵波达到最大值;当达到极限强度时,纵波速度下降幅度增大.而横波在极限强度的15.1%应力区域内,波速上升较快,但稍逊于纵波;当应力达到极限强度的35.9%时,横波达到最大值;当应力达到极限强度的92.8%时,出现波速下降幅度增大的拐点.16#与17#岩样表现出相对一致的规律,只是纵波达到最大值的应力水平有所提前(约68.02%),而横波则有所延后,毕竟该类岩心非均质性较强.与16#、17#岩样相比,20#、21#岩样均为相对致密白云岩,孔渗较低.从图2来看,纵横波波速曲线总体上均可分成三段,纵波第一上升阶段应力区域与横波波速最大值点有较好对应,纵波波速的最大值点与横波波速下降幅度增大点相对应,当岩样 达到极限强度后,纵横波波速降低幅度均有所增加.对于孔隙发育类岩心,在其压实阶段,波速上升的速度大于其他相对致密的岩样.在实验结果上表现为:图1中16#、17#岩样的a阶段斜率要大于图2中20#、21#岩样的a阶段斜率.

波速的任何变化特性都与岩石受压变形有关.结合应力$\!$-$\!$-$\!$应变曲线,排除特殊情况,横波波速最大值基本上出现在极限强度的30%$\sim$50%应力范围内,在该应力范围内,处在压实阶段结束和弹性压缩阶段,此阶段变形表现为裂缝的充分闭合和新裂缝的产生,即横波波速最大值与裂缝的闭合和产生有关;纵波波速最大值基本上出现在70%$\sim$90%应力范围内,此阶段变形表现为裂缝的不稳定扩展和贯通,亦即纵波波速的最大值与裂缝的不稳定扩展和贯通有关.由此说明,横波波速对裂缝比纵波更敏感. 图3很好地说明了以上分析.

图3   同一白云岩岩样纵、横波波速曲线对比图

Fig. 3   The comparison of longitudinal and transverse wave velocity curves of the same dolomite sample

2.2 波形及频谱曲线特性分析

17#岩样样采用单轴加载,峰值强度为23.15,MPa. 加载过程中,载荷为5.58, 14.26, 22.92,MPa条件下的纵波波形及4.64, 9.33,19.8,MPa条件下的横波波形分别见图4(a),图4(c),图4(e)和图5(a),图5(c),图5(e),对应的由FFT处理得到的频谱曲线分别见图4(b),图4(d),图4(f)和图5(b),图5(d),图5(f).

图4   17#白云岩纵波波形及频谱曲线(单轴)

Fig. 4   The longitudinal wave waveform and spectrum curve of 17# dolomite (uniaxial)

图5   17#白云岩横波波形及频谱曲线(单轴)

Fig. 5   The transverse wave waveform and spectrum curve of 17# dolomite (uniaxial)

通过观察发现,17#岩样由于孔隙比较发育,孔隙度和渗透率值均较高,密度相对于其他白云岩较低,由此导致声波的散射现象较严重.随着轴向应力增大,纵波波形信号强度变化缓慢,横波变化明显,横波比纵波能更好地反映岩样内部结构变化,波形图上体现为"鱼尾"状波列的出现,且出现在极限强度的40.3%处.在频谱曲线上,随着裂缝的不断产生,频谱曲线上低频端较高频端活跃,纵波的主振幅难以辨认,导致出现高振幅的低频峰,横波的频谱则没有纵波那样明显. 将17#岩样的波形和频谱的波幅和主频提取出来进行具体的分析,曲线如图6$\sim$图9所示.

图6   17#岩样纵波首波振幅与主频对比图

Fig. 6   The first wave amplitude and main frequency comparison chart of longitudinal wave(17#)

图7   17# 岩样纵波频谱主振幅与主频对比图

Fig. 7   The main amplitude of spectrum and main frequency comparison chart of longitudinal wave(17#)

图8   17#岩样横波首波振幅与主频对比图

Fig. 8   The first wave amplitude and main frequency comparison chart of transverse wave(17#)

图9   17#岩样横波频谱主振幅与主频对比图

Fig. 9   The main amplitude of spectrum and main frequency comparison chart of transverse wave(17#)

通过对波形和频谱中提取的振幅曲线分析发现,17#岩样纵波首波振幅曲线和对应的频谱主振幅曲线无明显的拐点,在岩样达到极限强度前,几乎以相同的幅度在上升;横波首波振幅曲线与对应的频谱主振幅曲线都有拐点存在,前者出现在岩样极限强度66.45%处,后者出现在56.49%处,曲线可以看出有3个阶段,但是不能 明显区分;对于频谱主频,纵波只在压密阶段发生一次上升的变化,之后便趋于稳定,而横波则在整个受压过程中变化较明显,这与横 波的传播方式和岩样的破坏方式(张性和剪切混合)有关系.

图10为18#岩样在围压18.9,MPa, 峰值强度237.6,MPa, 轴向载荷分别为10.84, 100.39, 237.54,MPa时的纵波波形及频谱曲线.

图10   18#白云岩纵波波形及频谱曲线(三轴)

Fig. 10   The longitudinal wave waveform and spectrum curve of 18# dolomite (triaxial)

18#岩样为砾屑白云岩,质地致密但不均匀,故孔隙度和渗透率均较低,密度较大,从波形和频谱曲线来看,该样波形曲线的末端显得比较活跃,且随着轴向差应力 增大,幅值有所增大,且在频谱曲线上毛刺现象较严重,原因在于岩样内部的砾屑和胶结物的声阻抗的不同,导致声波的绕射现象比较严重,且低频端比较发育.将18#岩样的波形和频谱的波幅和主频提取出来进行具体的分析,曲线如图11所示.

图11   18#岩样首波与频谱主振幅曲线(三轴纵波)

Fig. 11   The first wave and spectrum main amplitude curve of 18# sample (three-axis and longitudinal wave)

18#岩样为砾屑白云岩,质地致密但不均匀,故孔隙度和渗透率均较低,密度较大,从波形和频谱曲线来看,该样波形曲线的末端显得比较活跃,且随着轴向差应力的增加,幅值有所增大,且在频谱曲线上毛刺现象较严重,原因在于岩样内部的砾屑和胶结物的声阻抗的不同,导致声波的绕射现象比较严重,且低频端比较发育. 将18#岩样的波形和频谱的波幅和主频提取出来进行具体的分析,曲线如图11所示.

由于18#岩样的主频只在压密阶段的23.02,MPa和岩样破坏后的应力降至160,MPa的时候变化,而在其他受压过程中都没发生变化,故这里没有将主频对比图画出. 通过两个曲线对比发现,频谱主振幅曲线有明显的阶段性,第一个阶段为岩样压密阶段,在轴向压力为23.02,MPa的时候,亦即主频变化的应力点,在频谱主振幅曲线上此阶段为很小的一个阶段,在首波振幅曲线上则没有显示;在第二阶段内两振幅曲线都体现出较大幅度的上升趋势;在进入第三阶段后,首波振幅曲线便开始下降,而主振幅曲线上升幅度降低,原因是该岩样裂缝产生的方式比较复杂,为交错网状裂缝,因而对首波振幅影响较大,对频谱主振幅影响相对较小. 通过对比再一次发现,频谱曲线较好地反映了岩石受压的几个阶段.

3 岩石受压声学特性在裂缝研究中的应用

随着非常规油气资源勘探开发的快速发展,储层岩石裂缝成为当前研究的一大热点[29-35].通过前面的实验研究发现声学特性能够较灵敏的反映岩石内部裂缝的变化特征. 对于孔隙和裂缝发育的地层岩石来说,受压变形就意味着岩石内部旧裂缝的闭合、新裂缝的产生、稳定扩展、不稳定扩展、贯穿直至破坏.而岩石所处的应力和裂缝的变形状态,又决定了岩石的稳定状态.因此,在实验室中得到的岩石受压过程中声学参数(波速、波形、频谱)的变化特性,对于实际工程中地层岩石内部裂缝变形的预测和岩石稳定性的评价,都有着重要的科学指导意义.因此,本节结合波速、波形和频谱在岩石受压各个阶段所体现出的不同的变化特征,来论述岩石受压声学特性在裂缝变化研究方面的应用价值.

3.1 裂缝的闭合

对波速曲线而言,在波速达到峰值点之前,不论是纵波还是横波,曲线都可分为两个阶段,即快速上升阶段和缓慢上升阶段.从实验曲线来看,纵横波在第一阶段具有较好的一致性,纵、横波波速基本上在同一个应力或应变区域内处于快速上升阶段,该阶段基本上处于岩石极限强度的10%$\sim$30%应力范围内.由弹性波的传播理论可知,在此阶段波速的上升,主要是由于岩石受压裂缝的闭合,致使密度和弹性参数的增大,导致纵波波速和横波波速都快速上升,因此通过纵、横波波速曲线的快速上升阶段,可用来判断裂缝的闭合.

对频谱曲线而言,从频谱曲线上能较好的看出变化. 在岩样压密阶段,由于岩石内部裂缝的存在而吸收了声波的高频成分,因而在频谱曲线上低频成分较为活跃,随着岩石被压密,裂缝的闭合使得声波的高频成分得到释放,在频谱曲线上能非常明显的观察到,高频成分振幅增大,且高频成分逐渐取代低频成分成为频谱的主频率.

通过波形和频谱提取出的振幅曲线,在岩石的压密阶段也有很好的显示. 从所有振幅曲线来看,在岩石受压裂缝闭合阶段,振幅都处于低速的上升阶段.

3.2 裂缝的产生和稳定扩展

由于岩石内部新裂缝的产生,使得声波速度曲线进入第二个阶段,即上升幅度减小阶段,但是纵、横波分别又表现出了不同的现象.纵波在此阶段一直以低幅度的上升;而当裂缝处于稳定发展阶段后,横波则首先达到最大值,此时基本上处于岩石极限强度的40%$\sim$50%的应力范围内.

对于波形信号而言,与纵波信号相比,横波则有明显的响应.当岩石的应力状态处于极限强度的50%$\sim$60%范围内时,横波波列的尾部波形出现比较明显的"鱼尾状"散射波形,且随着裂缝的进一步扩展,此段波形信号有增强趋势.对应的频谱曲线中,与波形曲线相反,纵波的频谱则比横波表现更为明显.当岩石内部裂缝产生以后,由于裂缝对声波中高频部分的吸收作用,纵波频谱上低频部分振幅的上升幅度要强于高频部分,随着裂缝逐渐扩展,呈现出主频难以辨别的现象,甚至出现低频取代高频成为主频的现象.

4 结 论

(1)岩石在受压变形过程中,声波波速的变化较好地反映了岩石内部裂缝的闭合、产生、扩展和贯穿等变化.总的来说,横波波速比纵波能更好的预测裂缝的产生,而纵波对裂缝的非稳定发展或贯穿有较敏感的反映.在波速曲线的第一阶段,纵横波都呈现出快速上升阶段,预示着岩石的压实阶段;进入第二阶段后,横波波速首先达到峰值点,此时岩石所处的应力为极限强度的50%左右,纵波此时的上升速度也开始降低,此时预示着新裂缝的产生并开始扩展;进入第3个阶段后,纵波波速达到峰值点,横波也出现波速下降的拐点,此时应力为极限强度的80%左右,预示着裂缝的不稳定扩展和贯穿;对于波速曲线的最后阶段,纵波波速出现下降的拐点,部分横波也有对应的拐点,此时则说明了岩石达到了极限强度,即将破坏.

(2)波形变化的规律性也在一定程度上反映了岩石的变形. 纵、横波的波形信号幅度的增强,反映了岩石的压实;随着轴压的增大,纵、横波波形的末端都有散射波的出现,但横波波形末端的散射波信号要更为明显,且呈"鱼尾"状(此时应力点为极限强度的60%左右),此时预示着岩石内部裂缝的产生和稳定扩展.

(3)通过对波形进行傅里叶变换得到对应的频谱曲线也很好地反映了岩石内部结构变形情况.相比之下,纵波频谱曲线更能反映岩石裂缝的动态变化.随着岩石受力的增大,频谱曲线上的振幅都呈现出增大的趋势,标志着岩石的压实阶段;当频谱曲线上低频端较高频端活跃时,标志着裂缝的产生;对部分频谱曲线来说,低频还会取代高频成为主频.

(4)从波形曲线的首波中提取的振幅曲线和频域振幅谱中提取的主振幅的曲线,也能很好地反映岩石的变形情况. 和波速曲线一样,振幅曲线也呈明显的阶段性变化. 第一阶段,首波振幅和频谱主振幅都表现出较低上升的趋势,此为岩石的压实阶段;第二阶段,振幅都表现出快速上升趋势,主振幅比首波振幅更为明显,此时标志着岩石的弹性压缩阶段;第三阶段,主振幅又表现出比首波振幅更低的上升趋势,此时预示着裂缝的不稳定扩展;当曲线达到最大值后,曲线开始下降,两个振幅都在此时产生降低的突变点,此时,岩石已经产生贯通的破裂面.

本文在对白云岩受压声学特性研究的基础上,也对声学特性在岩石裂缝研究中的应用进行了理论性的阐述和探讨. 本研究对于地层岩石的动态长期监测和工程岩体的稳定性预测都具有重要的指导意义,可为地层岩石的稳定性评价提供一定的理论参考.

The authors have declared that no competing interests exist.


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利用MTS815岩石力学试验机和PCI-II声发射三维定位实时监测系统对取自锦屏II级水电站交通辅助洞的含自然裂隙大理岩岩样进行单轴压缩条件下的声发射(AE)测试,并结合AE振铃数实现对不同空间分布类型自然裂隙时空演化过程的精确定位和追踪。试验结果表明:含自然裂隙大理岩岩样受压破坏过程中的局部渐进特征显著,AE累计数曲线的上升与试验的加载过程和岩样内部的应力调整关系密切;单一型和平行型自然裂隙空间分布形式相对简单,在压应力水平较低时AE大事件(振铃数>20)随着压应力的渐增沿自然裂隙面展布,当压应力接近峰值强度时,AE大事件在裂隙面末端部位大量集聚,并朝着最终的实际破裂方向扩展;含交叉型自然裂隙岩样体内的AE大事件在初始压密阶段分布相对均匀,但随着压应力的持续增加,裂隙面附近的AE数量逐渐增加,并向裂隙面的交叉部位集聚;混合型自然裂隙结构最复杂,但仍不难根据AE大事件的空间分布确定岩样内部的软弱部位及相应的应力场变化规律。以上试验和分析结果对于深入研究岩体破裂失稳机制具有一定的意义,也可为现场微震监测提供指导。

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利用MTS815岩石力学试验机和PCI-II声发射三维定位实时监测系统对取自锦屏II级水电站交通辅助洞的含自然裂隙大理岩岩样进行单轴压缩条件下的声发射(AE)测试,并结合AE振铃数实现对不同空间分布类型自然裂隙时空演化过程的精确定位和追踪。试验结果表明:含自然裂隙大理岩岩样受压破坏过程中的局部渐进特征显著,AE累计数曲线的上升与试验的加载过程和岩样内部的应力调整关系密切;单一型和平行型自然裂隙空间分布形式相对简单,在压应力水平较低时AE大事件(振铃数>20)随着压应力的渐增沿自然裂隙面展布,当压应力接近峰值强度时,AE大事件在裂隙面末端部位大量集聚,并朝着最终的实际破裂方向扩展;含交叉型自然裂隙岩样体内的AE大事件在初始压密阶段分布相对均匀,但随着压应力的持续增加,裂隙面附近的AE数量逐渐增加,并向裂隙面的交叉部位集聚;混合型自然裂隙结构最复杂,但仍不难根据AE大事件的空间分布确定岩样内部的软弱部位及相应的应力场变化规律。以上试验和分析结果对于深入研究岩体破裂失稳机制具有一定的意义,也可为现场微震监测提供指导。
[5] 杨永杰,王德超,郭明福.

基于三轴压缩声发射试验的岩石损伤特征研究

. 岩石力学与工程学报,2014,33(1):98-104

DOI      URL      Magsci      摘要

利用MTS815岩石伺服试验系统和AE21C声发射监测仪,对灰岩进行三轴压缩声发射试验,利用声发射参数,分析三轴压缩条件下岩石的损伤演化特征。试验结果表明:(1) 相同试验条件下,检波器置于三轴室内时的声发射振铃计数和能量的最大值分别比置于室外时高27%和32%,表明,声发射检波器置于三轴室内能够接收到更全面、真实的声发射信号。(2) 围压使岩石压密阶段声发射活动降低,同时声发射振铃计数最大值稍滞后于岩样宏观破坏时间,说明围压提高了岩石的剪切强度和峰后承载能力。(3) 建立基于声发射累计振铃计数的岩石三轴压缩损伤演化模型,岩石的损伤演化过程可划分为初始损伤阶段、损伤稳定发展阶段、损伤加速发展阶段和损伤破坏阶段。初始损伤阶段,声发射参数较小;损伤稳定发展阶段,声发射活动明显活跃,振铃计数和能量逐渐增加;损伤加速发展阶段,声发射活动异常活跃,宏观破坏后不久声发射振铃计数和能量达到峰值;损伤破坏阶段,岩石仍具有相当的承载能力,在破坏过程中仍有声发射活动出现。

(Yang Yongjie, Wang Dechao, Guo Mingfu, et al.

Study of rock damage characteristics based on acoustic emission tests under triaxial compression

. Chinese Journal of Rock Mechanics and Engineering,2014,33(1):98-104 (in Chinese))

DOI      URL      Magsci      摘要

利用MTS815岩石伺服试验系统和AE21C声发射监测仪,对灰岩进行三轴压缩声发射试验,利用声发射参数,分析三轴压缩条件下岩石的损伤演化特征。试验结果表明:(1) 相同试验条件下,检波器置于三轴室内时的声发射振铃计数和能量的最大值分别比置于室外时高27%和32%,表明,声发射检波器置于三轴室内能够接收到更全面、真实的声发射信号。(2) 围压使岩石压密阶段声发射活动降低,同时声发射振铃计数最大值稍滞后于岩样宏观破坏时间,说明围压提高了岩石的剪切强度和峰后承载能力。(3) 建立基于声发射累计振铃计数的岩石三轴压缩损伤演化模型,岩石的损伤演化过程可划分为初始损伤阶段、损伤稳定发展阶段、损伤加速发展阶段和损伤破坏阶段。初始损伤阶段,声发射参数较小;损伤稳定发展阶段,声发射活动明显活跃,振铃计数和能量逐渐增加;损伤加速发展阶段,声发射活动异常活跃,宏观破坏后不久声发射振铃计数和能量达到峰值;损伤破坏阶段,岩石仍具有相当的承载能力,在破坏过程中仍有声发射活动出现。
[6] 赵星光,李鹏飞,马利科.

循环加、卸载条件下北山深部花岗岩损伤与扩容特性

. 岩石力学与工程学报,2014, 33(9):1740-1748

DOI      URL      Magsci      摘要

采用MTS815岩石力学试验机和声发射监测系统,研究我国高放废物地质处置库北山预选区深部花岗岩在三轴循环加、卸载条件下的损伤和扩容特性。基于试验结果,分析岩石全应力–应变曲线与累计声发射撞击数和事件数的时空分布关系,进而揭示其破裂演化机制。通过构建岩石在循环加、卸载过程中的塑性应变轨迹,获得峰后剪胀角随塑性剪切应变的变化规律,探讨岩石扩容对塑性剪切应变和围压的依赖性。研究结果表明:(1) 声发射事件增量最大值出现在应变软化阶段,在该阶段的反复加载是加剧其内部损伤和裂隙宏观贯通的主导因素,残余变形阶段的裂隙行为主要表现为宏观断裂面间的摩擦、滑移,岩石扩容率趋于恒定;(2) 卸载过程对于裂隙发展的影响远小于加载过程,由于裂隙的发展状态不同,在裂隙损伤应力( )之前和之后卸载导致的声发射特征具有显著的差异性;(3) 峰后剪胀角随塑性剪切应变的增加而减小,并随围压增加其衰减梯度不断减小,采用指数函数建立围压和塑性剪切应变为影响因素的剪胀角模型,可合理描述北山花岗岩的扩容特性。

(Zhao Xingguang, Li Pengfei, Ma Like, et al.

Damage and dilation characteristics of deep granite at Beishan under cyclic loading-unloading conditions

. Chinese Journal of Rock Mechanics and Engineering,2014, 33(9):1740-1748 (in Chinese))

DOI      URL      Magsci      摘要

采用MTS815岩石力学试验机和声发射监测系统,研究我国高放废物地质处置库北山预选区深部花岗岩在三轴循环加、卸载条件下的损伤和扩容特性。基于试验结果,分析岩石全应力–应变曲线与累计声发射撞击数和事件数的时空分布关系,进而揭示其破裂演化机制。通过构建岩石在循环加、卸载过程中的塑性应变轨迹,获得峰后剪胀角随塑性剪切应变的变化规律,探讨岩石扩容对塑性剪切应变和围压的依赖性。研究结果表明:(1) 声发射事件增量最大值出现在应变软化阶段,在该阶段的反复加载是加剧其内部损伤和裂隙宏观贯通的主导因素,残余变形阶段的裂隙行为主要表现为宏观断裂面间的摩擦、滑移,岩石扩容率趋于恒定;(2) 卸载过程对于裂隙发展的影响远小于加载过程,由于裂隙的发展状态不同,在裂隙损伤应力( )之前和之后卸载导致的声发射特征具有显著的差异性;(3) 峰后剪胀角随塑性剪切应变的增加而减小,并随围压增加其衰减梯度不断减小,采用指数函数建立围压和塑性剪切应变为影响因素的剪胀角模型,可合理描述北山花岗岩的扩容特性。
[7] 赵小平,陈淑芬.

基于声发射振幅分布的裂隙岩体破坏演化过程

. 岩石力学与工程学报,2015,34(增1):3012-3017

DOI      URL      [本文引用: 1]      摘要

In general,the problem of rock mechanics is the mechanical behavior of fractured rock-mass in the engineering scale,especially the strength distribution,deformation character and failure evolution of fractured rock-mass under loading. In this paper,the study of failure evolution process and differences between intact coal and fractured coal rock-mass with single fracture and multiple fractures,according to the distribution of max-amplitude of acoustic emission under uniaxial loading,is based on specimens of fractured coal rock-mass obtained by pre-loading on intact coal. The study results are as follows:the value of can describe the distribution regularity of max-amplitude of AE during the failure evolution process under loading,and the value increases with increasing block to the expansion of fractures in specimen;the value of decreases with increasing loading under different stress level and increase with increasing fracture under the same stress level;it can be considered as the precursor of specimen?s failure when the decrease of value becomes flat according to the regularity of value in intact coal and fractured coal rock-mass during the failure evolution process,and that can provide a test basis for the application of AE technology of monitoring and prediction in situ.

(Zhao Xiaoping, Chen Shufen.

Failure evolution prosess of fractured rockmass based on amplitude of acoustic emission

. Chinese Journal of Rock Mechanics and Engineering,2015,34(S1):3012-3017 (in Chinese))

DOI      URL      [本文引用: 1]      摘要

In general,the problem of rock mechanics is the mechanical behavior of fractured rock-mass in the engineering scale,especially the strength distribution,deformation character and failure evolution of fractured rock-mass under loading. In this paper,the study of failure evolution process and differences between intact coal and fractured coal rock-mass with single fracture and multiple fractures,according to the distribution of max-amplitude of acoustic emission under uniaxial loading,is based on specimens of fractured coal rock-mass obtained by pre-loading on intact coal. The study results are as follows:the value of can describe the distribution regularity of max-amplitude of AE during the failure evolution process under loading,and the value increases with increasing block to the expansion of fractures in specimen;the value of decreases with increasing loading under different stress level and increase with increasing fracture under the same stress level;it can be considered as the precursor of specimen?s failure when the decrease of value becomes flat according to the regularity of value in intact coal and fractured coal rock-mass during the failure evolution process,and that can provide a test basis for the application of AE technology of monitoring and prediction in situ.
[8] Xie HP, Liu JF, Ju Y, et al.

Fractal property of spatial distribution of acoustic emissions during the failure process of bedded rock salt

. International Journal of Rock Mechanics & Mining Sciences, 2011, 48(8): 1344-1351

URL      [本文引用: 1]     

[9] 武晋文, 赵阳升, 万志军.

高温均匀压力花岗岩热破裂声发射特性实验研究

. 煤炭学报, 2012, 37(7): 1111-1117

URL      Magsci      [本文引用: 1]      摘要

<p>为研究花岗岩体热破裂规律,通过实验研究了均匀压力(25 MPa)下大试件(200 mm&times; 400 mm )花岗岩在常温~500 ℃范围的声发射变化规律及特性,探讨了各个阶段声发射信号反映的岩石破裂特性。研究表明:① 330 ℃为花岗岩破裂声发射和热破裂性质转变的分界点,低于330 ℃ ,热破裂为弹性破裂,330 ℃以后,花岗岩出现局部塑性变形和破坏;② 330 ℃以后,局部塑性破坏造成大量低能量释放率的声发射产生,声发射密集区由小部分能量率很大的声发射和数量很多、低能量释放率的声发射组成,声发射密集区整体上累积释放能量较低;③ 声发射振铃率发生突变可以作为花岗岩内部微破裂带开始形成的标志,花岗岩从110和420 ℃开始分别经历了2次大的热破裂裂纹网络的改善。</p>

(Wu Jinwen, Zhao Yangsheng, Wan Zhijun, et al.

Experimental study of acoustic emission of granite due to thermal cracking under high temperature and isostatic stress

. Journal of China Coal Society, 2012, 37(7): 1111-1117 (in Chinese))

URL      Magsci      [本文引用: 1]      摘要

<p>为研究花岗岩体热破裂规律,通过实验研究了均匀压力(25 MPa)下大试件(200 mm&times; 400 mm )花岗岩在常温~500 ℃范围的声发射变化规律及特性,探讨了各个阶段声发射信号反映的岩石破裂特性。研究表明:① 330 ℃为花岗岩破裂声发射和热破裂性质转变的分界点,低于330 ℃ ,热破裂为弹性破裂,330 ℃以后,花岗岩出现局部塑性变形和破坏;② 330 ℃以后,局部塑性破坏造成大量低能量释放率的声发射产生,声发射密集区由小部分能量率很大的声发射和数量很多、低能量释放率的声发射组成,声发射密集区整体上累积释放能量较低;③ 声发射振铃率发生突变可以作为花岗岩内部微破裂带开始形成的标志,花岗岩从110和420 ℃开始分别经历了2次大的热破裂裂纹网络的改善。</p>
[10] 曾鹏, 刘阳军, 纪洪广.

单轴压缩下粗砂岩临界破坏的多频段声发射耦合判据和前兆识别特征

. 岩土工程学报, 2017, 39(3): 509-517

DOI      URL      [本文引用: 1]      摘要

为寻求岩石临界破坏判据和前兆特征,在粗砂岩单轴压缩声发射(AE)试验的基础上,研究了岩石破坏过程中AE信号频段占比随应力变化特征,重点分析高、低两个特征频段占比随应力变化规律,同时对两个特征频段中不同应力水平下AE幅值关联维数进行计算与分析,并建立了基于频段占比与应力间关系的多频段AE信号主频识别判据模型。研究表明:AE信号频段占比的分布特征能较好地诠释岩石破坏所经历的主要过程;岩石破坏过程中,较低频段AE信号(31.25~46.875 k Hz)占比先减小后增大,较高频段AE信号(140.625~156.25 k Hz)占比先增大后减小。在临界破坏状态下,高、低两个特征频段占比分别出现最大值和最小值,且二者中AE幅值关联维数都下降到最低。通过对特征频段占比与应力之间的耦合分析,利用特征频段占比、AE幅值关联维数的变化可更准确地对岩石临界破坏前兆进行判别和预测。

(Zeng Peng, Liu Yangjun, Ji Hongguang, et al.

Coupling criteria and precursor identification characteristics of multi-band acoustic emission of gritstone fracture under uniaxial compression

. Chinese Journal of Geotechnical Engineering, 2017, 39(3): 509-517 (in Chinese))

DOI      URL      [本文引用: 1]      摘要

为寻求岩石临界破坏判据和前兆特征,在粗砂岩单轴压缩声发射(AE)试验的基础上,研究了岩石破坏过程中AE信号频段占比随应力变化特征,重点分析高、低两个特征频段占比随应力变化规律,同时对两个特征频段中不同应力水平下AE幅值关联维数进行计算与分析,并建立了基于频段占比与应力间关系的多频段AE信号主频识别判据模型。研究表明:AE信号频段占比的分布特征能较好地诠释岩石破坏所经历的主要过程;岩石破坏过程中,较低频段AE信号(31.25~46.875 k Hz)占比先减小后增大,较高频段AE信号(140.625~156.25 k Hz)占比先增大后减小。在临界破坏状态下,高、低两个特征频段占比分别出现最大值和最小值,且二者中AE幅值关联维数都下降到最低。通过对特征频段占比与应力之间的耦合分析,利用特征频段占比、AE幅值关联维数的变化可更准确地对岩石临界破坏前兆进行判别和预测。
[11] 刘建坡, 徐世达, 李元辉.

预制孔岩石破坏过程中的声发射时空演化特征研究

. 岩石力学与工程学报, 2012, 31(12): 2538-2547

DOI      URL      Magsci      [本文引用: 1]      摘要

选取粗粒花岗岩和细粒砂岩,通过预制方孔和圆孔,开展单轴加载条件下岩石破坏声发射试验。采用单纯形定位算法,对岩石破裂过程中的声发射时空演化规律进行研究,并对声发射活动特征、能量释放率和空间相关长度进行分析。研究结果表明:对于预制孔间距与预制孔尺寸相同的试件,声发射事件主要在岩石中部群集,试件以中部剪切破坏为主,声发射三维定位事件直观反映裂纹初始、扩展直至贯通的动态演化过程;在整个加载过程中,颗粒较粗且大小不均的花岗岩试件声发射活动性较强,颗粒较细且均匀的砂岩试件声发射活动性在加载后期才开始增强;岩石破坏前,小尺度裂纹合并贯通形成大尺度裂纹,声发射率下降,能量释放率增强,出现声发射信号&ldquo;平静&rdquo;而能量释放&ldquo;不平静&rdquo;的现象;岩石在受载过程中,应力场通过迁移和重新分布逐步建立起长程相关性;岩石破坏前,空间相关长度显著增加,且在岩石破坏时达到最大值。

(Liu Jianpo, Xu Shida, Li Yuanhui, et al.

Studies of AE time-space evolution characteristics during failure process of rock specimens with prefabricated holes

. Chinese Journal of Rock Mechanics and Engineering, 2012, 31(12): 2538-2547 (in Chinese))

DOI      URL      Magsci      [本文引用: 1]      摘要

选取粗粒花岗岩和细粒砂岩,通过预制方孔和圆孔,开展单轴加载条件下岩石破坏声发射试验。采用单纯形定位算法,对岩石破裂过程中的声发射时空演化规律进行研究,并对声发射活动特征、能量释放率和空间相关长度进行分析。研究结果表明:对于预制孔间距与预制孔尺寸相同的试件,声发射事件主要在岩石中部群集,试件以中部剪切破坏为主,声发射三维定位事件直观反映裂纹初始、扩展直至贯通的动态演化过程;在整个加载过程中,颗粒较粗且大小不均的花岗岩试件声发射活动性较强,颗粒较细且均匀的砂岩试件声发射活动性在加载后期才开始增强;岩石破坏前,小尺度裂纹合并贯通形成大尺度裂纹,声发射率下降,能量释放率增强,出现声发射信号&ldquo;平静&rdquo;而能量释放&ldquo;不平静&rdquo;的现象;岩石在受载过程中,应力场通过迁移和重新分布逐步建立起长程相关性;岩石破坏前,空间相关长度显著增加,且在岩石破坏时达到最大值。
[12] Kim J, Lee K, Cho W, et al.

A comparative evaluation of stress--strain and acoustic emission methods for quantitative damage assessments of brittle rock

. Rock Mechanics and Rock Engineering, 2015, 48(2): 495-508

DOI      URL      [本文引用: 1]      摘要

The purpose of this study is to identify the crack initiation and damage stress thresholds of granite from the Korea atomic energy research institute’s Underground Research Tunnel (KURT). From this, a quantitative damage evolution was inferred using various methods, including the crack volumetric strain, b value, the damage parameter from the moment tensor, and the acoustic emission (AE) energy. Uniaxial compression tests were conducted, during which both the stress–strain and AE activity were recorded simultaneously. The crack initiation threshold was found at a stress level of 0.42–0.5302 σ c , and the crack damage threshold was identified at 0.62–0.8402 σ c . The normalized integrity of KURT granite was inferred at each stress level from the damage parameter by assuming that the damage is accumulated beyond the crack initiation stress threshold. The maximum deviation between the crack volumetric strain and the AE method was 16.002%, which was noted at a stress level of 0.8402 σ c . The damage parameters of KURT granite derived from a mechanically measured stress–strain relationship (crack volumetric strain) were successfully related and compared to those derived from physically detected acoustic emission waves. From a comprehensive comparison of damage identification and quantification methods, it was finally suggested that damage estimations using the AE energy method are preferred from the perspectives of practical field applicability and the reliability of the obtained damage values.
[13] Zhang Z, Zhang R, Xie H, et al.

Differences in the acoustic emission characteristics of rock salt compared with granite and marble during the damage evolution process

. Environmental Earth Sciences, 2015, 73(11): 6987-6999

DOI      URL      [本文引用: 1]      摘要

Rock salt cavities for energy storage are important elements of energy supply management and sustainability. The mechanical properties of other common rocks have already been adequately investigated, but a systematic characterization of the differences in acoustic emission (AE) characteristics among rock salt and other common rocks is needed. In this study, the AE characteristics of the full-regime uniaxial compression of rock salt and common rocks such as granite and marble were determined. A damage variable based on AE parameters and a methodology for its determination were established, including an analysis of the characteristics of the AE time鈥搒pace evolution, the AE amplitude distribution and the damage evolution based on AE parameters. Clear differences were observed in the AE characteristics of rock salt compared with granite and marble during the damage evolution process. The AE activity and energy release of rock salt with coarse grains and nonuniform structures decreased gradually with increasing stress level. The AE activity of rock salt appeared in a continuous, group-occurring form. The AE spatial distribution of rock salt was relatively uniform, without a definite rupture surface. The AE amplitude distribution varied slowly, and the proportion of AE events with small amplitudes increased gradually during compression in rock salt. Moreover, the damage in rock salt predominantly occured during the pre-peak period, resulting in a large damage variable of 0.9 at peak stress. By contrast, the damage variables of granite and marble are only 0.5 and 0.1, respectively, at peak stress. Rock salt exhibited less damage when approaching failure, resulting in a gentler and steadier process. And the plastic characteristics of rock salt are relatively obvious. These properties, to some extent, ensure the safety of underground storage engineering when rock salt is chosen as the medium.
[14] Nur A.

Effects of stress on velocity anisotropy in rocks with cracks

. Journal of Geophysical Research,1971,76(8):2022-2034

DOI      URL      [本文引用: 1]      摘要

The effective elastic compliance of rock that contains cracks is evaluated from energy considerations, as first proposed by Eshelby [1957]. The compliance of rock depends on the compliance of the solid matrix, the directional distribution of the cracks, an 090004inhomogeneity090005 interaction tensor, and the shape distribution of cracks, which are assumed to be shaped like pennies. The effective compliance is linearly elastic for small-amplitude elastic waves. Anisotropic crack distribution causes elastic anisotropy, with associated acoustic birefringence. Nonhydrostatic stress causes stress-induced anisotropy, owing to anisotropic closure of cracks. Although velocities are uniquely determined from the distribution of cracks, the distribution cannot be determined uniquely from the velocities. The theoretical results compare favorably with measured compressional velocities and crack distribution in Salisbury granite and with measured stress-induced compressional and shear velocity anisotropy in Barr0108 granite.
[15] Le Pichon A.

Analysis of infrasonic waves generated by the rupture of the Sumatra $M_{w} =9.0$ in the Indian ocean

. Geophysical Research Abstracts,2005

[16] Chou HT, Chang YL, Zhang SC.

Acoustic signals and geophone response of rainfall-induced debris flows

. Journal of the Chinese Institute of Engineers, 2013,36(3): 335-347

DOI      URL      [本文引用: 1]      摘要

The infrasound and geophone response of rainfall-induced debris flows are explored based on field studies. Both the stony-type debris flow which occurred in Houyenshan, Miaoli County, Taiwan, on 10 June 2006 and the muddy viscous debris flow which occurred in Jiangjia Gully, Yunnan, China, on 11 August 2007 were examined. Infrasound propagates a long distance in the atmosphere at the speed of sound due to its low adsorption in the air and the high reflectivity of the ground. The infrasonic signals induced by debris flows are related to the magnitude and composition of the debris flows. Our findings show that the peak acoustic frequencies for the Houyenshan stony debris flows are within the range 1509000940 Hz, while the corresponding geophone signals exhibit peak frequencies within 1509000950 Hz. The peak frequencies of the viscous debris flows in Jiangjia Gully fell within the range 509000913 Hz. During the propagation of debris flows, the amplitude of air pressure in Houyenshan was generally greater than 1.0 Pa, and the ground velocity greater than 0.2 mm/s. The Hilbert090009Huang transform approach is adopted to analyze the non-stationary acoustic signals of the debris flows. Stony-type debris flows tend to occur in Houyenshan, Taiwan, once the total rainfall exceeds 67 mm preceded by heavy hourly rainfall.
[17] Ashraf MA, Carl HS, Chandra SR.

Effect of cementation on ultrasonic velocities in sandstones

. Geophysics,2007,72(2) :E53-E58

DOI      URL      [本文引用: 1]      摘要

Abstract We determine the acoustic velocities for samples cored from the Jauf and Unayzah sandstone formations of Saudi Arabia. We use microstructural analysis including thin sections and point counting to quantify cementation. Velocities in these formations are strongly controlled by the combination of porosity and cementation. Consequently, rocks of similar porosity but with different cementation materials display different velocities. The objective of this study is to understand the effect of cementation on the acoustic velocity. Cements in these two formations have variable compositions and properties. Pure quartz overgrowth plays a major role in increasing velocities while clay and clay coatings play a minor role. We found that clay coatings inhibit the quartz overgrowth cement leading to a decrease in velocities. Understanding the influence of various cementation types on velocity, and thus elastic properties in sandstone cores, enables an understanding of the variation of sonic velocities and moduli across these formations. The uniqueness of this study is that we emphasize the quantification of the role of cement and not just mineral volume.
[18] 尤明庆,苏承东,李小双.

损伤岩石试样的力学特性与纵波速度关系研究

. 岩石力学与工程学报,2008,27(3):458-467

DOI      URL      Magsci      [本文引用: 1]      摘要

讨论大理岩试样围压下压缩和砂岩试样经历不同温度烘烤后的力学特性与纵波速度的关系。岩石不是线弹性材料,纵波速度、杨氏模量和强度是岩石试样力学性质的不同宏观表现。大理岩块曾经历地质应力,局部的低强度材料可使其附近材料承受较小荷载,晶粒之间维持相对较好的接触状态,因而试样初始纵波速度和强度呈负相关性。围压下压缩时大理岩试样承载能力随着变形增大可以大致保持恒定,但内部材料产生损伤弱化,损伤特性与围压、轴向变形有关。损伤大理岩试样的纵波速度和单轴强度、杨氏模量之间具有相关性,但例外现象大量存在。粗砂岩主要由矿物颗粒和胶结物构成,试样烘烤后胶结物发生变化而刚度降低,因而纵波速度和初始切线模量随温度增加而降低;但岩石的热变形可以改善颗粒间接触状态,降温之后因摩擦作用等并不会消失,因而在500 ℃之内平均模量随温度增加变化不大,强度却有增大趋势;其后平均模量和强度才开始降低。

(You Mingqing,Su Chengdong,Li Xiaoshuang.

Study on relation between mechanical properties and longitudinal wave velocities for damaged rock samples

. Chinese Journal of Rock Mechanics and Engineering,2008,27(3):458-467(in Chinese))

DOI      URL      Magsci      [本文引用: 1]      摘要

讨论大理岩试样围压下压缩和砂岩试样经历不同温度烘烤后的力学特性与纵波速度的关系。岩石不是线弹性材料,纵波速度、杨氏模量和强度是岩石试样力学性质的不同宏观表现。大理岩块曾经历地质应力,局部的低强度材料可使其附近材料承受较小荷载,晶粒之间维持相对较好的接触状态,因而试样初始纵波速度和强度呈负相关性。围压下压缩时大理岩试样承载能力随着变形增大可以大致保持恒定,但内部材料产生损伤弱化,损伤特性与围压、轴向变形有关。损伤大理岩试样的纵波速度和单轴强度、杨氏模量之间具有相关性,但例外现象大量存在。粗砂岩主要由矿物颗粒和胶结物构成,试样烘烤后胶结物发生变化而刚度降低,因而纵波速度和初始切线模量随温度增加而降低;但岩石的热变形可以改善颗粒间接触状态,降温之后因摩擦作用等并不会消失,因而在500 ℃之内平均模量随温度增加变化不大,强度却有增大趋势;其后平均模量和强度才开始降低。
[19] 刘维国,单钰铭,刘荣和.

砂岩扩容过程中超声波衰减的实验研究

. 成都理工大学学报(自然科学版),2006,33(6):611-616

DOI      URL      [本文引用: 1]      摘要

利用振幅谱比法对砂岩扩容过程中超声波衰减的实验结果进行分析表 明:岩石存在裂纹稳定性传播与裂纹的非稳定性传播和宏观破裂过程;在前期研究三轴实验中横波速度极大值作为岩石应力门槛值的基础上,增添了横波的衰减系数 的最小值,即品质因子的最大值作为新的判据.提出了裂纹稳定性传播阶段与裂纹的非稳定性传播阶段分界的特征是:横波的衰减系数、横波损伤因子、泊松比、体 积应变曲线在该分界处出现拐点.将其归属于裂纹传播过程中具有局部贯通时破裂的特征,该分界点处在岩石的应力门槛值与抗压强度之间.此项研究结果具有广泛 的应用价值.

(Liu Weiguo,Shan Yuming,Liu Ronghe.

Study on ultrasonic attenuation in the process of rock dilatancy by amplitude spectrum ratio

. Journal of Chengdu University of Technology(Science and Technology),2006,33(6):611-616 (in Chinese))

DOI      URL      [本文引用: 1]      摘要

利用振幅谱比法对砂岩扩容过程中超声波衰减的实验结果进行分析表 明:岩石存在裂纹稳定性传播与裂纹的非稳定性传播和宏观破裂过程;在前期研究三轴实验中横波速度极大值作为岩石应力门槛值的基础上,增添了横波的衰减系数 的最小值,即品质因子的最大值作为新的判据.提出了裂纹稳定性传播阶段与裂纹的非稳定性传播阶段分界的特征是:横波的衰减系数、横波损伤因子、泊松比、体 积应变曲线在该分界处出现拐点.将其归属于裂纹传播过程中具有局部贯通时破裂的特征,该分界点处在岩石的应力门槛值与抗压强度之间.此项研究结果具有广泛 的应用价值.
[20] 陈乔,刘向君,刘洪.

层理性页岩地层超声波透射实验

.天然气工业, 2013, 33(8): 140-144

DOI      URL      Magsci      [本文引用: 1]      摘要

<p>层理发育的硬脆性页岩的声波响应特征是页岩气开发过程中测井资料应用的基础,为获得对层理性页岩储层超声波传播特性的认识,选取渝东南地区下志留统龙马溪组野外露头岩块,通过波速初步筛选出横向各向同性的大岩样,在此基础上钻取不同层理方向的小岩柱,进行室内多频率超声波透射实验,以获取不同层理下的声波传播规律。实验结果表明:①实验用岩样以黑色、灰黑色及深灰色页岩、粉砂质泥岩为主,孔隙度变化范围为1.5%~2.5%,大部分岩样的渗透率小于1 mD;②在0&deg;~90&deg;范围内,随层理倾角的增加,波速减小趋势明显,衰减系数增加;③波速与孔隙度呈现较好的负相关性,随孔隙度增加,衰减系数增加且增加程度随层理倾角变大而加剧;④波速与频率呈对数增加的趋势,频散现象明显,衰减系数随频率增加而增大。所得到的页岩层理与声波属性相关性的实验结果,可为页岩气开发过程中建立准确的地层岩石强度剖面及井壁稳定分析提供实验依据。</p>

(Chen Qiao, Liu Xiangjun, Liu Hong,et al.

An experimental study of ultrasonic penetration througu bedding shale reservoir

. Natural Gas Industry, 2013, 33(8): 140-144 (in Chinese))

DOI      URL      Magsci      [本文引用: 1]      摘要

<p>层理发育的硬脆性页岩的声波响应特征是页岩气开发过程中测井资料应用的基础,为获得对层理性页岩储层超声波传播特性的认识,选取渝东南地区下志留统龙马溪组野外露头岩块,通过波速初步筛选出横向各向同性的大岩样,在此基础上钻取不同层理方向的小岩柱,进行室内多频率超声波透射实验,以获取不同层理下的声波传播规律。实验结果表明:①实验用岩样以黑色、灰黑色及深灰色页岩、粉砂质泥岩为主,孔隙度变化范围为1.5%~2.5%,大部分岩样的渗透率小于1 mD;②在0&deg;~90&deg;范围内,随层理倾角的增加,波速减小趋势明显,衰减系数增加;③波速与孔隙度呈现较好的负相关性,随孔隙度增加,衰减系数增加且增加程度随层理倾角变大而加剧;④波速与频率呈对数增加的趋势,频散现象明显,衰减系数随频率增加而增大。所得到的页岩层理与声波属性相关性的实验结果,可为页岩气开发过程中建立准确的地层岩石强度剖面及井壁稳定分析提供实验依据。</p>
[21] 熊健,梁利喜,刘向君.

川南地区龙马溪组页岩岩石声波透射实验研究

.地下空间与工程学报, 2014, 10(5): 1071-1077

URL      Magsci      [本文引用: 1]      摘要

为了获得对龙马溪组页岩储层声波传播特性的规律,选取川南地区下志留统龙马溪组页岩野外露头岩块,钻取不同层理角度的岩心(10个层理角度),采用透射法系统地分析了龙马溪组页岩不同层理角度的岩石纵横波速度,计算页岩岩石动弹性力学参数。研究结果表明川南地区龙马溪组页岩的纵横波速度呈显著的正线性关系,页岩岩石的纵横波速度比均值或纵波速度随层理角度的增加而减小;页岩岩石的动弹性模量、体积模量及剪切模量与岩石的纵横波速度有较好相关性,呈指数关系,而动泊松比与岩石纵波速度有良好线性相关性;声波速度随层理角度的增加或频率减小而减小,与频率呈良好的正对数关系;声波衰减系数随层理角度的增加或频率的增加而增大,与频率呈弱线性关系。

(Xiong Jian, Liang Lixi, Liu Xiangjun, et al.

Experimental study on acoustic penetration through the Longmaxi formation shale rock in south region of Sichuan Basin

. Chinese Journal of Underground Space and Engineering, 2014, 10(5): 1071-1077 (in Chinese))

URL      Magsci      [本文引用: 1]      摘要

为了获得对龙马溪组页岩储层声波传播特性的规律,选取川南地区下志留统龙马溪组页岩野外露头岩块,钻取不同层理角度的岩心(10个层理角度),采用透射法系统地分析了龙马溪组页岩不同层理角度的岩石纵横波速度,计算页岩岩石动弹性力学参数。研究结果表明川南地区龙马溪组页岩的纵横波速度呈显著的正线性关系,页岩岩石的纵横波速度比均值或纵波速度随层理角度的增加而减小;页岩岩石的动弹性模量、体积模量及剪切模量与岩石的纵横波速度有较好相关性,呈指数关系,而动泊松比与岩石纵波速度有良好线性相关性;声波速度随层理角度的增加或频率减小而减小,与频率呈良好的正对数关系;声波衰减系数随层理角度的增加或频率的增加而增大,与频率呈弱线性关系。
[22] King MS.

Elastic wave propagation in and permeability for rocks with multiple parallel fractures

. International Journal of Rock Mechanics and Mining Sciences, 2002, 39(8): 1033-1043

DOI      URL      [本文引用: 1]      摘要

The Serra da Mesa Hydroelectric Power Plant, located in the Tocantins river, 210 km north of Brasilia, Brazil, has been completed and power (1200 MW) has been generated since 1998. This project includes one of the largest underground structures in Brazil, totalling 550,000 in 3 of underground excavations in rock for the hydraulic circuit which was excavated in very high quality granite. Geotechnical investigations, laboratory tests and geological mapping showed that the rock mass could be considered as a continuous, homogeneous, isotropic and linearly elastic (CHILE) material. In situ tests, for obtaining the natural stress tensor, namely hydraulic fracturing and small flat jack tests (SFJ), were executed. The hydraulic fracturing tests were performed in two boreholes, at the planned position of the future underground structures. SFJ were executed in a test gallery especially constructed for the purpose. These latter tests confirmed the in situ rock stress data obtained from the hydraulic fracturing tests. This paper presents a new technique for interpretation of the SFJ results. This is achieved by inputting the SFJ measurements into a 3D program that compiles the influence matrix of the excavated rock mass domain and then, via the least square technique, the determination of the stress tensor. All the equations are fully developed and the methodology is presented in its entirety. The successful application of the methodology is also presented, with comparisons between the results obtained and the in situ stress tensor determined by other methods. (C) 2002 Elsevier Science Ltd. All rights reserved.
[23] Petružálek M, Vilhelm J, Rudajev V, et al.

Determination of the anisotropy of elastic waves monitored by a sparse sensor network

. International Journal of Rock Mechanics and Mining Sciences, 2013, 60: 208-216

DOI      URL      [本文引用: 1]      摘要

A method of velocity anisotropy analysis based on conventional ultrasonic transmission technique is proposed. Multiple transducers are used both to monitor acoustic emission and to measure velocities in different propagation directions. A sparse network of transducers located on the rock core surface allows approximation of elastic waves velocity distribution as an ellipsoidal surface. The shape and orientation of velocity ellipsoid is a measure of velocity anisotropy. A study of changes in velocity anisotropy and its orientation was performed on uniaxially loaded migmatite rock samples with distinct foliation. The velocity measurement was carried out during applying a uniaxial constant strain-rate loading. Orientation of the velocity ellipsoid corresponded to the anisotropy of rock structure up to activation of a failure plane. Prior to brittle failure, the axis of minimum velocity rotated from its initial direction normal to the foliation to a direction normal to the failure surface. The practical importance of the ellipsoid model lies in its simplicity and in its general applicability, which allows the use of measurement in a sparse sensor network. The-use of time-variable ellipsoidal velocity model led to a better localization of acoustic emission events during the sample loading when compared to the use of time-variable isotropic velocity model. The position of the failure plane determined by clustering of acoustic events foci coincided closely with observed sample failure. (C) 2013 Elsevier Ltd. All rights reserved.
[24] Chow TM, Meglis IL, Young RP.

Progressive microcrack development in tests on Lac du Bonnet granite---II. Ultrasonic tomographic imaging

. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1995, 32(8): 751-761

[本文引用: 1]     

[25] Ougier-Simonin A, Fortin J, Guéguen Y, et al.

Cracksin glass under triaxial conditions

. International Journal of Engineering Science, 2011, 49(1): 105-121

DOI      URL      [本文引用: 1]      摘要

This experimental work documents the mechanical evolution of synthetic glass (SON68) under compressive triaxial stresses (hydrostatic and deviatoric conditions). The experimental setup enabled to monitor and vary independently confining pressure (range: [0,0250]02MPa) and axial stress (up to 68002MPa) at room temperature. An optimized set of sensors allowed us to perform measurements during the experiments of: (i) axial and radial deformation, (ii) - and -elastic wave velocities, and (iii) acoustic emissions. In addition, in some samples, initial crack densities up to a value of 0.24 were introduced by thermal cracking. We compare the original synthetic glass data set to results obtained in the same experimental conditions on thermally cracked glass and on a basaltic rock with similar petrophysical properties (porosity, chemistry).Stress–strain data depict original linear elastic glass properties even up to an axial stress of 68002MPa (under 1502MPa confining pressure). A strong strength decrease (37002MPa at 1502MPa confining pressure) is observed for thermally cracked samples. Elastic wave velocity data highlight that cracks are mostly closed at a confining pressure of 653002MPa. The basaltic rock seems to correspond to an intermediate state between an original and a thermally treated glass. In all samples, damage was accompanied by dynamic crack propagation, producing large magnitude acoustic emissions. Thanks to a continuous recorder, we could locate a number of acoustic emissions in order to image the microcracking pattern evolution prior to failure.
[26] 张国凯, 李海波, 夏祥.

岩石波速与损伤演化规律研究

. 岩石力学与工程学报, 2015, 34(11): 2270-2277

DOI      URL      Magsci      [本文引用: 1]      摘要

岩石波速随应力的变化对研究损伤演化具有重要意义。采用颗粒流程序建立9种不同模型,在模型内设置激发源和接收器,通过对激发源施加速度脉冲并记录接收器信号模拟波的传播与衰减,可以得出:配位数与孔隙率呈线性变化关系,波幅衰减与枝矢量分布直接相关,波速主要受孔隙率、配位数张量和刚度张量影响。模拟岩石双轴压缩应力&ndash;应变过程中轴向和侧向波速,微裂纹主要沿轴向分布,相比剪切裂纹,张拉裂纹优势导向与轴向夹角较小,且随着裂纹的增多,波速及枝矢量分布各向异性逐渐增大。波速变化的内在原因是新接触点的形成、黏结断裂和接触点的分开,波速变化依赖于刚度张量相应分量的平方根,二者变化规律基本保持一致。通过刚度张量及枝矢量分布变化确定损伤特性及导向,是一种量化波速与损伤的新方法,可为损伤演化规律研究提供参考。

(Zhang Guokai, Li Haibo, Xia Xiang, et al.

Wave velocity and damage development of rock

. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(11):2270-2277 (in Chinese))

DOI      URL      Magsci      [本文引用: 1]      摘要

岩石波速随应力的变化对研究损伤演化具有重要意义。采用颗粒流程序建立9种不同模型,在模型内设置激发源和接收器,通过对激发源施加速度脉冲并记录接收器信号模拟波的传播与衰减,可以得出:配位数与孔隙率呈线性变化关系,波幅衰减与枝矢量分布直接相关,波速主要受孔隙率、配位数张量和刚度张量影响。模拟岩石双轴压缩应力&ndash;应变过程中轴向和侧向波速,微裂纹主要沿轴向分布,相比剪切裂纹,张拉裂纹优势导向与轴向夹角较小,且随着裂纹的增多,波速及枝矢量分布各向异性逐渐增大。波速变化的内在原因是新接触点的形成、黏结断裂和接触点的分开,波速变化依赖于刚度张量相应分量的平方根,二者变化规律基本保持一致。通过刚度张量及枝矢量分布变化确定损伤特性及导向,是一种量化波速与损伤的新方法,可为损伤演化规律研究提供参考。
[27] 张国凯,李海波,夏祥.

单轴加载条件下花岗岩声发射及波传播特性研究

. 岩石力学与工程学报, 2017, 36(5): 1133-1144

URL      [本文引用: 1]      摘要

采用声波、声发射一体化装置,研究单轴压缩下花岗岩波速与声发射演化规律,通过宏细观方法确定各应力门槛值,研究裂纹扩展不同阶段声发射演化及波传播规律。结果表明:细观裂纹的演化与宏观变形直接对应,由于微裂纹主要沿轴向扩展,导致轴向刚度对裂纹起裂及贯通的敏感度弱于非线性增长的侧向变形,瞬时泊松比曲线斜率变化点与应力门槛值对应,声发射测试确定的起裂应力比宏观应变法偏小,但反映了微裂纹的初始萌生;采用实测波速变化分析声发射震源的时空及幅值演化分布,较好地描绘了裂纹的扩展过程,由于不同阶段声发射信号的幅值及能量存在差异,导致声发射特征参数演化规律差异较大(尤其在损伤应力之后),AE能量在破坏前呈突发性增长,可作为灾害性破坏的前兆;加载初始阶段,由于微裂隙的闭合,波速及波幅均随应力逐渐增大,但增加速率逐渐下降,侧向波速在闭合应力附近基本达到峰值,此后一定阶段基本保持不变,但其他方向波速则继续增大,随着波传播方向与径向夹角的增大,波速增加幅度及波速下降点对应的应力(损伤应力前、后)逐渐增大,峰值应力附近对应波速下降幅度减小;波速受损伤演化的影响要滞后于声发射事件。

(Zhang Guokai, Li Haibo, Xia Xiang, et al.

Experiment study on acoustic emission and wave propagation in granite under uniaxial compression

. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(5): 1133-1144 (in Chinese))

URL      [本文引用: 1]      摘要

采用声波、声发射一体化装置,研究单轴压缩下花岗岩波速与声发射演化规律,通过宏细观方法确定各应力门槛值,研究裂纹扩展不同阶段声发射演化及波传播规律。结果表明:细观裂纹的演化与宏观变形直接对应,由于微裂纹主要沿轴向扩展,导致轴向刚度对裂纹起裂及贯通的敏感度弱于非线性增长的侧向变形,瞬时泊松比曲线斜率变化点与应力门槛值对应,声发射测试确定的起裂应力比宏观应变法偏小,但反映了微裂纹的初始萌生;采用实测波速变化分析声发射震源的时空及幅值演化分布,较好地描绘了裂纹的扩展过程,由于不同阶段声发射信号的幅值及能量存在差异,导致声发射特征参数演化规律差异较大(尤其在损伤应力之后),AE能量在破坏前呈突发性增长,可作为灾害性破坏的前兆;加载初始阶段,由于微裂隙的闭合,波速及波幅均随应力逐渐增大,但增加速率逐渐下降,侧向波速在闭合应力附近基本达到峰值,此后一定阶段基本保持不变,但其他方向波速则继续增大,随着波传播方向与径向夹角的增大,波速增加幅度及波速下降点对应的应力(损伤应力前、后)逐渐增大,峰值应力附近对应波速下降幅度减小;波速受损伤演化的影响要滞后于声发射事件。
[28] 张晓平, 王思敬, 刘泉声.

一种测量岩石压缩裂纹扩展过程声波波速的连续测量方法

. 工程地质学报, 2018, 26(1): 91-96

URL      [本文引用: 1]      摘要

中低围压或单轴压缩荷载条件下,可以将脆性岩石材料的裂纹扩展过程划分为原生裂纹压密、新生裂纹起裂并稳定扩展、不稳定裂纹扩展和交互贯通以及峰后5个主要发展阶段。含预制裂纹试样的直接观测法、应变监测、声发射(AE)监测、声波波速测试、CT(computerized tomography)扫描、微电镜观察等间接监测方法被用来研究裂纹起裂和扩展过程。本文基于在中、低围压以及单轴压缩荷载条件下,脆性岩石材料首先产生张拉裂纹,并优先沿加载方向发育的规律,提出采用声波波速连续测量方法进行岩石加载过程波速的连续观测,有助于分析裂纹扩展过程中声波波速的变化,为研究裂纹扩展过程提供一种间接测量手段。

(Zhang Xiaoping,Wang Sijing,Liu Quansheng.

A continuing measure method for acoustic wave velocity measurement during cracking processes of rock

. Journal of Engineering Geology,2018, 26(1): 91-96 (in Chinese))

URL      [本文引用: 1]      摘要

中低围压或单轴压缩荷载条件下,可以将脆性岩石材料的裂纹扩展过程划分为原生裂纹压密、新生裂纹起裂并稳定扩展、不稳定裂纹扩展和交互贯通以及峰后5个主要发展阶段。含预制裂纹试样的直接观测法、应变监测、声发射(AE)监测、声波波速测试、CT(computerized tomography)扫描、微电镜观察等间接监测方法被用来研究裂纹起裂和扩展过程。本文基于在中、低围压以及单轴压缩荷载条件下,脆性岩石材料首先产生张拉裂纹,并优先沿加载方向发育的规律,提出采用声波波速连续测量方法进行岩石加载过程波速的连续观测,有助于分析裂纹扩展过程中声波波速的变化,为研究裂纹扩展过程提供一种间接测量手段。
[29] Yang SQ, Jing HW.

Strength failure and crack coalescence behavior of brittle sandstone samples containing a single fissure under uniaxial compression

. International Journal of Fracture, 2011, 168(2): 227-250

DOI      URL      [本文引用: 1]      摘要

http://link.springer.com/article/10.1007%2Fs10704-010-9576-4
[30] LokajíČek T, Goel RK, Rudajev V, et al.

Assessment of velocity anisotropy in rocks

. International Journal of Rock Mechanics and Mining Sciences, 2013, 57: 142-152

DOI      URL      摘要

Acoustic emissions generated during the mechanical loading of rocks provide information about the process of their fracturing and therefore have been used in the research of rock fracturing for many years. Laboratory loading experiments are used as a model of seismic processes in the field. Continuous loading is typically used to model natural tectonic processes, whereas stepwise loading can... [Show full abstract]
[31] 尹国庆,张辉,袁芳.

白云岩储层地质力学特征分析及在储层改造优化应用------以塔中东部为例

. 天然气地球科学,2015, 26(7): 1277-1288

DOI      URL      Magsci      摘要

<p>针对塔里木油田塔中东部中下寒武统白云岩储层岩性组分复杂,石膏含量较高,压裂改造效果差等问题,在岩石力学实验、岩石组分精细确定基础上建立白云岩储层弹性模量、泊松比、强度、可压裂性等计算模型,并分析不同岩性组分岩石力学参数的影响规律,同时通过井筒资料分析地应力方位,建立地应力计算模型,分析不同组分含量对地应力影响,确定精细地应力剖面,并分析纵向变化规律|另一方面,开展天然裂缝产状信息处理、提取,分析主应力与裂缝走向关系,利用已压裂井资料确定天然裂缝内聚力、滑动摩擦系数,并定量计算天然裂缝面正应力、剪应力,确定不同注入压力下的开启率,从而确定中深5井超深、致密、含膏白云岩储层以压裂为主的改造方案,在此基础上根据分层应力剖面、水平应力差、地层可压裂性、天然裂缝力学特征优化压裂施工层段、泵注程序、分段射孔簇、施工压力等。</p>

(Yin Guoqing, Zhang Hui, Yuan Fang, et al.

Geomechanical characteristics of dolomite reservoir and its application in stimulation optimization: An example of east of Tazhong

. Natural Gas Geoscience, 2015, 26(7): 1277-1288 (in Chinese))

DOI      URL      Magsci      摘要

<p>针对塔里木油田塔中东部中下寒武统白云岩储层岩性组分复杂,石膏含量较高,压裂改造效果差等问题,在岩石力学实验、岩石组分精细确定基础上建立白云岩储层弹性模量、泊松比、强度、可压裂性等计算模型,并分析不同岩性组分岩石力学参数的影响规律,同时通过井筒资料分析地应力方位,建立地应力计算模型,分析不同组分含量对地应力影响,确定精细地应力剖面,并分析纵向变化规律|另一方面,开展天然裂缝产状信息处理、提取,分析主应力与裂缝走向关系,利用已压裂井资料确定天然裂缝内聚力、滑动摩擦系数,并定量计算天然裂缝面正应力、剪应力,确定不同注入压力下的开启率,从而确定中深5井超深、致密、含膏白云岩储层以压裂为主的改造方案,在此基础上根据分层应力剖面、水平应力差、地层可压裂性、天然裂缝力学特征优化压裂施工层段、泵注程序、分段射孔簇、施工压力等。</p>
[32] 林皋.

地下结构地震响应的计算模型

. 力学学报, 2017, 49(3): 528-542

DOI      URL      摘要

地震时地下结构在围岩的约束作用下发生变形,其动态特性与地面结构有很大不同.自二十世纪七八十年代以来,地下结构抗震设计与研究取得了很大进展.总的看来,工程设计中普遍采用的计算方法与设计导则大都建立在比较简单假定的基础上,实际的岩土介质条件都是十分复杂的.地下结构抗震研究的近期成果则表现在对地下结构动力分析中的波动散射问题提出了波函数展开法以及边界积分方程方法等多种计算方法.但计算相对复杂,在工程设计中的推广应用有一定困难.此文致力于地下结构计算模型的改进,使之具有良好的计算精度与效率,又便于工程应用.为此,提出了一种地下结构抗震响应分析的新的计算模型.模型具有较广泛的适应性,可以进行河谷、孔洞、地下铁道、隧洞等地下结构的散射与绕射分析.对于复杂层状的地质条件,提出了格林函数求解简便而有效的方法.数值算例论证了方法的精度和效率.

(Lin Gao.

A computational model for seismic response analysis of underground stauctures

. Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(3): 528-542 (in Chinese))

DOI      URL      摘要

地震时地下结构在围岩的约束作用下发生变形,其动态特性与地面结构有很大不同.自二十世纪七八十年代以来,地下结构抗震设计与研究取得了很大进展.总的看来,工程设计中普遍采用的计算方法与设计导则大都建立在比较简单假定的基础上,实际的岩土介质条件都是十分复杂的.地下结构抗震研究的近期成果则表现在对地下结构动力分析中的波动散射问题提出了波函数展开法以及边界积分方程方法等多种计算方法.但计算相对复杂,在工程设计中的推广应用有一定困难.此文致力于地下结构计算模型的改进,使之具有良好的计算精度与效率,又便于工程应用.为此,提出了一种地下结构抗震响应分析的新的计算模型.模型具有较广泛的适应性,可以进行河谷、孔洞、地下铁道、隧洞等地下结构的散射与绕射分析.对于复杂层状的地质条件,提出了格林函数求解简便而有效的方法.数值算例论证了方法的精度和效率.
[33] 何川, 齐春, 封坤. 基于

D-P 准则的盾构隧道围岩与衬砌结构相互作用分析

. 力学学报, 2017, 49(1): 31-40

DOI      URL      Magsci      摘要

<p>在进行盾构隧道管片衬砌结构载荷计算时,常采用全土柱或压力拱理论计算围岩松动压力,但当盾构隧道面临深埋条件且需计入形变压力时,该方法难以适用.鉴于此,基于Drucker-Prager屈服准则,推导了考虑渗流效应影响下围岩与衬砌结构相互作用的弹塑性解析解,给出了围岩弹、塑性区应力与位移、塑性区半径等关键参数与支护阻力间关系的解析式.阐述了上述解析结果在确定衬砌结构载荷中的应用,即建立围岩与衬砌结构静力平衡状态并求二者对应曲线的交点.进一步地,考虑接头引起管片衬砌结构整体刚度降低对围岩与衬砌结构相互作用的影响,引入刚度折减系数,并在衬砌结构围岩压力确定中对施工期流固耦合效应的影响和渗流力对衬砌结构支护特性曲线的影响进行了简化处理.最后,通过算例将解析解与水下盾构隧道载荷实测值和数值计算值进行了比较.结果表明:用解析方法得到的施工期和稳定期的管片衬砌结构围岩压力比现场实测值分别大28%和12%,稳定期围岩压力比数值计算值大5%,可为类似工程的设计施工提供一定的参考价值.</p>

(He Chuan, Qi Chun, Feng Kun, et al.

Theoretical analysis of interaction between surrounding rocks and linging strcture of shield tunnel based on Drucker-Prager yield criteria

. Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(1): 31-40 (in Chinese))

DOI      URL      Magsci      摘要

<p>在进行盾构隧道管片衬砌结构载荷计算时,常采用全土柱或压力拱理论计算围岩松动压力,但当盾构隧道面临深埋条件且需计入形变压力时,该方法难以适用.鉴于此,基于Drucker-Prager屈服准则,推导了考虑渗流效应影响下围岩与衬砌结构相互作用的弹塑性解析解,给出了围岩弹、塑性区应力与位移、塑性区半径等关键参数与支护阻力间关系的解析式.阐述了上述解析结果在确定衬砌结构载荷中的应用,即建立围岩与衬砌结构静力平衡状态并求二者对应曲线的交点.进一步地,考虑接头引起管片衬砌结构整体刚度降低对围岩与衬砌结构相互作用的影响,引入刚度折减系数,并在衬砌结构围岩压力确定中对施工期流固耦合效应的影响和渗流力对衬砌结构支护特性曲线的影响进行了简化处理.最后,通过算例将解析解与水下盾构隧道载荷实测值和数值计算值进行了比较.结果表明:用解析方法得到的施工期和稳定期的管片衬砌结构围岩压力比现场实测值分别大28%和12%,稳定期围岩压力比数值计算值大5%,可为类似工程的设计施工提供一定的参考价值.</p>
[34] 文龙飞, 王理想, 田荣.

动载下裂纹应力强度因子计算的改进型扩展有限元法

. 力学学报, 2018, 50(3): 599-610

DOI      URL      摘要

相较于常规扩展有限元法(extended finite element method, XFEM), 改进型扩展有限元法(improved XFEM) 解决了现有方法线性相关与总体刚度矩阵高度病态问题, 在数量级上提升了总体方程的求解效率, 克服了现有方法在动力学问题中的能量正确传递、动态应力强度因子数值震荡、精度低下问题. 本文基于改进型XFEM, 采用Newmark 隐式时间积分算法, 重点研究了动载荷作用下扩展裂纹尖端应力强度因子的求解方法, 与静力学方法相比, 增加了裂纹扩展速度项与惯性项的贡献. 通过数值算例研究了网格单元尺寸、质量矩阵、时间步长、裂尖加强区域、惯性项、扩展速度项及相互作用积分区域J-domain的网格与单元尺寸对动态应力强度因子求解精度的影响, 验证了改进型XFEM计算动态裂纹应力强度因子方法的有效性. 针对文献中具有挑战性的 "I 型半无限长裂纹先稳定后扩展"问题, 改进型XFEM给出目前为止精度最好的动态应力强度因子数值解.

(Wen Longfei, Wang Lixiang, Tian Rong.

Accurate computation on dynamic SIFs using improved XFEM

. Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(3): 599-610 (in Chinese))

DOI      URL      摘要

相较于常规扩展有限元法(extended finite element method, XFEM), 改进型扩展有限元法(improved XFEM) 解决了现有方法线性相关与总体刚度矩阵高度病态问题, 在数量级上提升了总体方程的求解效率, 克服了现有方法在动力学问题中的能量正确传递、动态应力强度因子数值震荡、精度低下问题. 本文基于改进型XFEM, 采用Newmark 隐式时间积分算法, 重点研究了动载荷作用下扩展裂纹尖端应力强度因子的求解方法, 与静力学方法相比, 增加了裂纹扩展速度项与惯性项的贡献. 通过数值算例研究了网格单元尺寸、质量矩阵、时间步长、裂尖加强区域、惯性项、扩展速度项及相互作用积分区域J-domain的网格与单元尺寸对动态应力强度因子求解精度的影响, 验证了改进型XFEM计算动态裂纹应力强度因子方法的有效性. 针对文献中具有挑战性的 "I 型半无限长裂纹先稳定后扩展"问题, 改进型XFEM给出目前为止精度最好的动态应力强度因子数值解.
[35] 万义钊, 刘曰武, 吴能友.

基于离散裂缝的多段压裂水平井数值试井模型及应用

. 力学学报, 2018, 50(1): 147-156

URL      [本文引用: 1]      摘要

水平井压裂技术已经成为开发低渗透油气藏、页岩气藏和致密气场等非常规油气藏的关键技术.基于离散裂缝模型,对裂缝进行简化,建立了二维多段压裂水平井有限导流裂缝数值试井模型,利用有限元方法求解模型,获得多段压裂水平井试井理论曲线和压力场特征.分析表明:多段压裂水平井的试井理论曲线一共分为7个阶段:井筒储存段、裂缝线性流段、裂缝–地层双线性流段、裂缝干扰段、地层线性流段、系统径向流段和边界作用段,其中裂缝–地层双线性流段和裂缝干扰段是其典型特征.分析了裂缝数量、裂缝间距、裂缝不对称、裂缝不等长和裂缝部分缺失等因素对试井理论曲线的影响,结果表明:裂缝数量和裂缝间距对试井理论曲线的影响最大.较多的裂缝、较大裂缝间距、对称的裂缝和等长的裂缝有利于降低压裂水平井井底的流动阻力,提高产能.将建立的数值试井模型应用于四川盆地一口多段压裂水平井的压力恢复测试的数值试井解释,结果表明:本文建立的模型可以较好地拟合压力恢复测试数据,可以获得裂缝的导流能力和裂缝长度,为压裂效果评价和压裂设计提供指导.

(Wan Yizhao, Liu Yuewu, Wu Nengyou, et al.

A numerical well test model for multi-fractured horizontal wells based on discrete-fracture model and its application

. Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(1): 147-156 (in Chinese))

URL      [本文引用: 1]      摘要

水平井压裂技术已经成为开发低渗透油气藏、页岩气藏和致密气场等非常规油气藏的关键技术.基于离散裂缝模型,对裂缝进行简化,建立了二维多段压裂水平井有限导流裂缝数值试井模型,利用有限元方法求解模型,获得多段压裂水平井试井理论曲线和压力场特征.分析表明:多段压裂水平井的试井理论曲线一共分为7个阶段:井筒储存段、裂缝线性流段、裂缝–地层双线性流段、裂缝干扰段、地层线性流段、系统径向流段和边界作用段,其中裂缝–地层双线性流段和裂缝干扰段是其典型特征.分析了裂缝数量、裂缝间距、裂缝不对称、裂缝不等长和裂缝部分缺失等因素对试井理论曲线的影响,结果表明:裂缝数量和裂缝间距对试井理论曲线的影响最大.较多的裂缝、较大裂缝间距、对称的裂缝和等长的裂缝有利于降低压裂水平井井底的流动阻力,提高产能.将建立的数值试井模型应用于四川盆地一口多段压裂水平井的压力恢复测试的数值试井解释,结果表明:本文建立的模型可以较好地拟合压力恢复测试数据,可以获得裂缝的导流能力和裂缝长度,为压裂效果评价和压裂设计提供指导.

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