单轴加载条件下煤岩超声各向异性特征实验

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赵宇, 张玉贵, 周俊义. 单轴加载条件下煤岩超声各向异性特征实验[J]. 物探与化探, 2017,41(2): 306-310.
ZHAO Yu, ZHANG Yu-Gui, ZHOU Jun-Yi. An experimental study of ultrasonic anisotropy of coal under uniaxial loading[J]. Geophysical and Geochemical Exploration, 2017,41(2): 306-310. 复制到剪切板

Doi:10.11720/wtyht.2017.2.17
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单轴加载条件下煤岩超声各向异性特征实验

赵宇¹, 张玉贵², 周俊义²

1.河南理工大学土木工程学院,河南焦作 454000

2. 河南理工大学安全科学与工程学院,河南焦作 454000

作者简介: 赵宇(1981-),男,讲师,博士研究生,从事煤(煤层气)储层渗透性研究工作。Email:zyxgll2000@163.com

收稿日期: 2016-07-25

基金: 国家科技重大专项“全国重点煤矿区瓦斯(煤层气)赋存规律和控制因素”(2011ZX05040-005); 河南省科技攻关计划项目“煤体吸附膨胀变形各向异性特性实验研究”(162102310427)

摘要

在煤岩弹性波响应特征研究中,较少系统地考虑轴压对煤岩纵、横波速度和衰减的影响。基于此,选取平煤八矿3种不同变质程度煤样,制备垂直层理、平行层理垂直面割理和平行层理垂直端割理3类煤样,进行煤岩单轴应力作用下的超声测试。实验结果表明:①在自然状态下,3种变质程度煤样3个方向的纵、横波速度以及品质因子均存在各向异性,一般情况下平行层理的两个方向纵、横波速度以及品质因子均大于垂直层理方向;②煤岩的纵、横波速度随着轴压的增加呈现先快速增加,后缓慢增大,直至煤样破坏后波速迅速降低的阶段性变化规律,横波速度阶段性变化规律不如纵波明显;③3个方向品质因子都随着应力的增加呈现先增加后减小的变化趋势,且 Q_s普遍比 Q_p大;④不同变质程度煤样,纵、横波速度和品质因子差异均比较明显,1/3焦煤纵、横波速度大于焦煤大于肥煤。

关键词: 单轴加载; 各向异性; 弹性波速度; 衰减; 割理

中图分类号:P631.4 文献标志码:A 文章编号:1000-8918(2017)02-0306-05

An experimental study of ultrasonic anisotropy of coal under uniaxial loading

ZHAO Yu¹, ZHANG Yu-Gui², ZHOU Jun-Yi²

1.School of Civil Engineering,Henan Polytechnic University,Jiaozuo 454000,China

2.College of Safety Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China

Abstract

In the study of coal rock elastic wave response characteristics,the influence of axial compression on longitudinal wave,transverse wave velocity and attenuation has not been given enough comprehensive consideration.In view of such a situation,three kinds of coal samples which experienced different grades of metamorphism were chosen from the Pingdingshan No.8 mine.Vertical-bedding samples,parallel-bedding and vertical-face cleat samples,parallel-bedding and vertical-butt cleat samples were prepared to conduct water absorption and ultrasonic experiment.Some experimental results have been obtained:First,in the natural state,longitudinal,transverse wave velocity and quality factor in three directions of the three kinds of coal samples are anisotropic,generally longitudinal,transverse wave velocity and quality factor in two directions parallel to bedding are greater than the corresponding data perpendicular to bedding plane.Second,in the coal rock,the longitudinal and transverse wave velocity increases rapidly with the increase of axial pressure in the early stages.After that,the velocity increases slowly and the wave velocity decreases rapidly until the coal sample is destroyed,the transverse wave velocity is not as obvious as the longitudinal wave.Third,in the three directions,the quality factor increases firstly and then decreases with the increase of stress,and Q_S is generally larger than that of Q_P.Fourth,in coal samples of different metamorphic grades,longitudinal,transverse wave velocity and quality factor differences are more obvious,longitudinal,transverse wave velocity of 1/3 coke is greater than that of coking coal and that of the fat coal.

Keyword: uniaxial loading; anisotropy; elastic wave velocity; attenuation; cleat

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0 引言

煤系地层结构及物性特征对煤炭的井下安全高效开采及煤层气的开发具有重大的现实意义。岩石超声波测试技术是通过研究超声波穿过岩石后的参数变化, 间接了解岩体的物理力学特性及结构特征^{[1, 2, 3, 4]}。目前已广泛用于岩石、岩体和土体动弹性参数测试、岩体结构分类、参数确定以及岩体质量评价等方面。针对岩石的声学响应特征, 国内外学者分别从压力、温度、水分、密度、孔隙流体等因素对超声波速度的影响作了大量的研究工作^{[5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]}, 并获得了众多的研究成果。孟召平等^[5]采集石炭— 二叠系煤系地层的岩芯进行了实验室超声波测试, 研究表明沉积岩石的纵波速度和横波速度随着岩石密度、围压和含水量的增大而增大。赵明阶^[6]从岩石的变形特性出发, 建立了在单轴加载、卸载和重加载过程中岩石声学特性的理论模型, 并对大理岩、灰岩和玄武岩3种岩石进行了单轴循环加载过程中的超声波测试实验, 得出岩石在单轴加载过程中, 微裂隙的闭合是影响岩石轴向声学特性的主要因素。李琼^[7]对沁水盆地煤层样品进行了不同压力条件下的煤样超声波测试, 得出煤岩样的纵波、横波速度随着压力的增加而增大, 煤岩样的纵波、横波速度与压力之间表现出较好的二次项相关关系。周锋^[8]模拟实际煤层埋藏应力状态条件进行煤样超声波速度测试, 得出随着围压的增加, 煤样的纵横波速都呈现增大趋势, 当围压达到10 MPa时, 煤样内部孔隙大部分已经闭合压实, 裂隙的方位会对超声波在煤岩中的传播速度产生一定的影响。

从目前研究的现状来看, 以往对于岩体超声波的研究涉及较多的主要为岩性较为均质的火成岩 $\begin{matrix} ^{[6, 1819]} \end{matrix}$ , 对于非均质程度较高的沉积岩尤其是煤体的物理力学性质的研究较少, 目前对于煤体超声特性的研究大多反应围压对煤岩超声响应特征的影响^[20], 而对轴压对煤岩超声响应特征的影响鲜有报道。基于此, 笔者利用平煤八矿煤样, 按照垂直层理、平行层理垂直面割离和平行层理垂直端割离3个方向制备煤样, 采用自主研发的煤岩三轴物性特征试验系统, 进行煤岩单轴加载条件下超声响应特征测试。

1 实验研究

1.1 实验装置及煤样制备

实验采用河南理工大学煤岩三轴物性特征试验系统, 该系统可以测试不同类型煤样在单轴、三轴应力和不同孔隙压力下的物性特征。此设备超声测试部分由脉冲信号发生器、超声换能器、放大器、示波器等组成。该系统的超声换能器是集成在三轴夹持器中轴向压头上的, 可在同一状态下分别测纵波和横波。采用蜂蜜作为耦合剂同时测试纵波和横波。煤岩超声特征测试系统结构如图1所示。

实验煤样取自平煤八矿, 采集煤样基础参数见表1。考虑到煤样制备过程中, 成功率偏低, 所以井下采集煤样重点挑选边长不小于200 mm的原煤煤块, 按图2中的x、y、z三个方向取芯, x方向是平行层理垂直端割理方向、y方向是平行层理垂直面割理方向、z方向为垂直层理方向, 取芯后用切割机将上下端面打磨光滑、平行, 制备煤样试件Φ 50 mm× 100 mm。

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	图1 三轴状态下煤岩超声特征测试系统结构

表1 采集煤样基本参数表

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	图2 煤体结构示意及取样方向

1.2 实验方法

实验利用超声波脉冲透射法测量, 本次超声波脉冲统一选用100 kHz的稍低频率。

纵、横波速度计算按公式

$\begin{matrix} v_{p} = L / t_{p} - t_{p 0}, v_{s} = L / t_{s} - t_{s 0} \end{matrix}$ (1)

进行。式中:v_p为纵波速度(m/s); v_s 为横波速度(m/s); L为发射接收换能器中心间的距离(m); t_p为纵波在样品中的走时(s); t_s为横波在样品中的走时(s); t_p0、 t_s0为测试系统的延迟时间(s)。

品质因子Q值采用振幅衰减法^[21]进行计算:

$\begin{matrix} Q = - πft / \ln [\frac{A (x)}{A_{0}}] 。 \end{matrix}$ （2）

式中:Q为品质因子; f为主频(Hz); A₀为未通过介质的子波振幅; A(x)为通过介质的透射波振幅; t为透射波初至时间(s)。

因实验需要同时测试煤样在单轴加载条件下的纵波和横波特征, 因此选取蜂蜜作为煤样与换能器之间的耦合剂, 将煤柱装入三轴岩芯夹持器, 保证煤柱与轴向压头充分接触; 开始自动加载轴压泵给煤样提供持续的单轴压力, 每加载0.5 Mpa后进行保压20 min; 然后采集纵波和横波信号, 读出、记录首波振幅, 最后将数字示波器显示的波形数据导出, 这样依次直至煤样破裂。

2 单轴加载条件下超声响应实验分析

通过实验, 获得了平煤八矿3种不同变质程度煤样在不同单轴应力下纵、横波速度和品质因子的测试数据。在加载过程中每级加载0.5 Mpa, 直至煤样破裂。表2和表3分别截取了部分应力下的纵波和横波速度以及品质因子值。

表2 实验煤样v_p、Q_p测试结果

表3 实验煤样v_s、Q_s测试结果

从表2和表3中可以看出在未加载时, 不同变质程度煤样x、y、z三个方向纵、横波速度均存在明显的各向异性, 平行层理的2个方向波速明显大于垂直层理方向, 表明在煤岩成分相近的情况下, 煤样内部结构差异即本身裂隙的发育方位是造成煤岩物性特征各向异性的主要原因。

图3~6可以看出不同变质程度煤样, 纵、横波速度和品质因子差异均比较明显, 1/3焦煤纵、横波速度大于焦煤大于肥煤, 煤的变质程度影响煤体孔、裂隙的发育, 因此影响煤体超声响应特征。

从图3、4可以看出煤岩轴向纵波速度随着单轴应力的增加呈现阶段性变化, 在初始压密阶段纵波速度明显增大, 品质因子Q_p也逐渐增大, 随后声速呈线性缓慢增加, 而品质因子Q_p变化不明显。当应力达到约90 %左右的破坏强度时, 煤岩声速有较明显的下降。这说明了煤岩在单轴加载过程中, 微裂隙的闭合是影响岩石轴向声学特性的主要因素。

从图4可以看出相比于平行层理的x和y方向而言, 垂直层理的z方向上Q_p相对较小, 说明在单轴加载条件下纵波沿z方向要比其他两个方向衰减更严重。这与沿z方向煤样的压实效应最大有关。随着加载时间的持续, 不同变质程度煤样3个方向煤柱纵波波速和衰减变化规律相似, 且各向异性特征比较明显。

从图5、6可以看出随着轴向应力的不断增加, 横波波速也呈现明显的阶段性增加特征, 但是煤样3个方向发生波速阶段性变化的拐点有所不同, 随着加载时间的延长, 波速继续增加, 直至后来煤样破坏, 波速迅速下降。1/3焦煤品质因子Q_s逐渐增大, 焦煤和肥煤品质因子Q_s逐渐减小, 这可能与焦煤和肥煤的裂隙比较发育有关。

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	图3 实验煤样v_p与轴向压力统计结果

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	图4 实验煤样Q_p与轴向压力的统计结果

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	图5 实验煤样v_s与轴向应力的统计结果

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	图6 实验煤样Q_s与轴向应力的统计结果

3 结论

1)煤样的纵、横波速度以及品质因子都存在各向异性, 一般情况下平行层理的两个方向纵、横波速度以及品质因子均大于垂直层理方向。

2)在单轴加载条件下, 煤岩轴向纵、横波速度随着应力的增加呈现阶段性变化规律, 在压密阶段, 波速明显增大, 品质因子显著增加; 随后声速呈线性缓慢增加, 而衰减系数则缓慢减小; 这说明了岩石在单轴加载过程中, 微裂隙的闭合是影响岩石轴向声学特性的主要因素。

3)不同变质程度煤样, 纵、横波速度和品质因子差异均比较明显, 再次印证了煤的变质程度影响煤体孔、裂隙的发育, 因此影响煤体超声响应特征。

4)对于含水(气)煤体超声特征与各向异性机理研究, 目前通过实验研究也初步得出随着煤样吸水率的不断增加, 其纵波速度逐渐增加, 横波速度略有波动, 但变化幅度远小于纵波。由于煤对气体的吸附效应, 在轴压和围压保持不变的条件下, 煤柱从负压状态到注气吸附状态并随着注气时间的延长, 波速是先下降, 然后缓慢升高。这对于进一步研究含水(气)煤体承压条件下的超声响应规律奠定了基础。

The authors have declared that no competing interests exist.

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2000

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... 岩石超声波测试技术是通过研究超声波穿过岩石后的参数变化,间接了解岩体的物理力学特性及结构特征^[1,2,3,4] ...

2010

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李东会, 董守华, 赵小翠, 等. 煤储层各向异性地震波场模拟[J]. 物探与化探, 2010, 34(5): 604-609.

In this paper, systematic classification was conducted for the fissure systems of China's coal seams, and the main causes for the different types of fissures were described. Based on 2D, 2C anisotropic elastic waveequation staggering grid highorder finitedifference numerical simulation, the authors carried out the numerical simulation of elastic wave field for the isotropy model and the water-saturated and dry media 2D layered model with fracturebearing coal seams of high fracturing density. The results show that, in comparison with the fracturesfree coalseam, the fracturesbearing coalseam has the following characteristics: the surge impedance of the boundary plane at the top and the bottom is changed due to the change of wave velocity, causing the change of dynamic characteristics of the wave. The AVO phenomenon is especially obvious. The characteristics of x component and z omponent are opposite in dry fractural media and in watersaturated fractural media, and the velocity of wave is faster in watersaturated fractural media than in dry fractural media. It is thus thought that coalseam fractures are detectable by using anisotropy theory.

1.School of Resources and Geoscience, CUMT, Xuzhou221008, China; 2.Faculty of Safety Engineering, CUMT, Xuzhou221008, China；3.CBM Branch Company of North China Oilfield, Jincheng048000, China；4.School of Economics and Management, Changchun University of Science and Technology, Changchun130022, China

对中国煤层的裂隙系统进行了系统分类;阐述了各类裂隙的主要成因。基于二维二分量各向异性弹性波方程交错网格高阶有限差分法数值模拟,对各向同性介质模型和高裂隙密度(含干裂隙和饱和水裂隙)煤层的二维层状模型进行了弹性波场数值模拟。结果表明:煤层含裂隙后与不含裂隙时相比,反射时差的变化已不足以识别,但由于波速的改变会使煤层顶底、界面的波阻抗发生变化,从而引起波的动力学特征的改变,AVO 现象尤其明显。含气和含水裂隙煤层中在x分量和z分量表现为极性相反，而且含水裂隙煤层中的波速比含气裂隙煤层的波速要快。因此,应用各向异性理论研究煤层裂隙的特征是可能的。

... 岩石超声波测试技术是通过研究超声波穿过岩石后的参数变化,间接了解岩体的物理力学特性及结构特征^[1,2,3,4] ...

1956

0.0

... 岩石超声波测试技术是通过研究超声波穿过岩石后的参数变化,间接了解岩体的物理力学特性及结构特征^[1,2,3,4] ...

1998

0.0

... 岩石超声波测试技术是通过研究超声波穿过岩石后的参数变化,间接了解岩体的物理力学特性及结构特征^[1,2,3,4] ...

2008

0.0

... 针对岩石的声学响应特征,国内外学者分别从压力、温度、水分、密度、孔隙流体等因素对超声波速度的影响作了大量的研究工作^{[5,6,7,8,9,10,11,12,13,14,15,16,17]},并获得了众多的研究成果 ...

... 孟召平等^[5]采集石炭#cod#x02014 ...

1999

0.0

赵明阶, 吴德伦. 单轴受荷条件下岩石的声学特性模型与实验研究[J]. 岩土工程学报, 1999, 21(5): 540-545.

This paper gives a theoretical model for ultrasonic properties of rock with microcrack under uniaxial loading, unloading and reloading, on the basis of analyzing microcrack deformations by fracture mechanical theory and setting microcrack equivalent model. The experiment of ultrasonic measurement of marble, limestone and basalt under uniaxial cycle loading has been performed.In general,the experimental results have a good agreement with the theoretical predictions.

Dept. of River and Ocean Engineering Chongqing Jiaotong Institute of Communication Chongqing 400074 Institute of Architecture and Engineering Chongqing Jianzhu University Chongqing 400045

从岩石的变形特性出发，通过等效裂纹模型的建立，给出了岩石在单轴加载、卸载和重加载过程中岩石声学特性的理论模型；对大理岩、灰岩和玄武岩三种岩石进行了单轴循环加载过程中的超声波测试实验，实验结果与理论计算基本吻合。

... 赵明阶^[6]从岩石的变形特性出发,建立了在单轴加载、卸载和重加载过程中岩石声学特性的理论模型,并对大理岩、灰岩和玄武岩3种岩石进行了单轴循环加载过程中的超声波测试实验,得出岩石在单轴加载过程中,微裂隙的闭合是影响岩石轴向声学特性的主要因素 ...

2013

0.0

... 李琼^[7]对沁水盆地煤层样品进行了不同压力条件下的煤样超声波测试,得出煤岩样的纵波、横波速度随着压力的增加而增大,煤岩样的纵波、横波速度与压力之间表现出较好的二次项相关关系 ...

2012

0.0

... 周锋^[8]模拟实际煤层埋藏应力状态条件进行煤样超声波速度测试,得出随着围压的增加,煤样的纵横波速都呈现增大趋势,当围压达到10 MPa时,煤样内部孔隙大部分已经闭合压实,裂隙的方位会对超声波在煤岩中的传播速度产生一定的影响 ...

1998

0.0

刘斌, Kern

, Popp

不同围压下孔隙度不同的干燥及水饱和岩样中的纵横波速度及衰减[J]. 地球物理学报, 1998, 41(4): 537-546.

Q-values for P-and S-waves along with the respective velocities have been determined for a low-porosity granite （0.7%） from Petras （Portugal）,a mid-porosity graywacke （9%） and a high-porosity sandstone （21%） from Xinjiang under confining pressures up to 600MPa （for dry samples） or 300MPa （for wet samples）.The simultaneous measurements of velocities and Q provide information on the mechanisms of attenuation,especially for an assessment of whether the predominant damping mechanism is in shear or in compression.Through analysis,we may find that,as confining pressure increases the ratio between damping related to compressive strain and which related to shear strain decreases in the low-porosity granite but increases in the mid-porosity gmywacke and the high-porosity sandstone,also this ratio is bigger in wet sample than in dry sample and the difference between them is proportional to the sample's porosity.At high confining pressures the velocities are determined by the mineral composition and the single crystal properties of the major constituents.In contrast,the Q-values are mainly controlled by grain boundary effects.

1. Dept.of Earth and Space Sci.,Uni.of Sci.and Tech.Of China, Advanced Research Centre for Geoseience and Astronomy,Third World Academy of Science,Hefei 230026,China; 2. Mineralogisch-Petrographisches Institut,Kiel University,Olshausenstr.40,24098 Kiel,Germany

选择具有不同孔隙度的三种岩石样品,在最高达600MPa （干燥样品）或300MPa （水饱和样品）的不同围压条件下,同时测量了在其中传播的纵、横波的速度及衰减。对于低孔隙度的花岗岩,干燥和水饱和样品的 Q 值几乎没有差别,但与干燥样品相比,水饱和样品中的纵波速度较高而横波速度稍低。对于中等孔隙度的杂砂岩,干燥样品和水饱和样品的波速和 Q 值及其随围压的变化有明显的不同。在高孔隙度的砂岩中这种不同更加显著。综合分析同时测得的纵、横波速度和 Q 值可以发现,当围压增加时,低孔隙度的花岗岩中同体应变相关的能量损失与同剪切应变相关的能量损失之比减小,但在中等孔隙度的杂砂岩和高孔隙度的砂岩中这一比值增大;同时,水饱和样品中的这一比值要比干燥样品中的大,而且它们之间的差别同样品的孔隙度正相关。

1997

0.0

席道瑛, 邱文亮, 程经毅, 等. 饱和多孔岩石的衰减与孔隙率和饱和度的关系[J]. 石油地球物理勘探, 1997, 32(2): 196-201.

Seismic wave attenuation in rock means wave energy loss in rock.From thelow-frequency resonance vibration experiment of sandstones which are filled with different fluids,we can obtain some relations,namely,the relation between attenuation and temperature,the linear relation between attenuation and porosity,and the relation between attenuation and saturation.These relation curves indicate that the sandstone with higher porosity has lower peak-attenuation temperature but higher peak attenuation,and that the attenuation grows with the increase of porosity or saturation of sandstone(note:the full saturation reduces attenuation).The experiment result favours the improvement of oil recovery ratio.

China University of Science and Technology, No.96 Jinzhai Road, Hefei City, Anhui provenct 230026

地震波在岩石中的衰减实际上是指波的振动能量在岩石内部的损耗。本文通过作低频共振实验,获得了不同饱和流体砂岩的衰减与温度关系曲线、衰减与砂岩孔隙率线性关系曲线、以及衰减与饱和度关系曲线。从中可以看出:衰减峰的峰温随砂岩孔隙率的增大向低温方向移动;峰高随砂岩孔隙率的增大而增高;衰减量随砂岩孔隙率的增大而增加,也随砂岩饱和度的增加而增大。当砂岩达到全饱和时,其衰减反而减小。这项实验结果对提高油气田的采收率是有益的。

2012

0.0

王赟, 许小凯, 张玉贵. 六种不同变质程度煤的纵横波速度特征及其与密度的关系[J]. 地球物理学报, 2012, 55(11): 3754-3761.

A lab ultrasonic measurement of six metamorphic kinds of coals was conducted under 25 degrees C and 0.1 MPa condition. And then some phenomena were concluded as follows: There are better linear correlations between pressure wave (P-wave) velocity and density, shear wave (S-wave) velocity and density; and the correlation coefficients of strike, dip and vertical directions are different and decreasing. Also there are positive linear correlation between P- and S-wave velocity in the same direction. However, there are great difference between velocities of different directions, especially in the strike and the vertical direction. The average anisotropy is about 0.1 and even more. Through comparing and analyzing the measured values with the estimated values, according to Gardner and Castagna formula, a non-tolerated error was found, which means that these two experience formulas cannot be applied to coal, and a suitable coal formula should be used in coal seam seismic exploration.

[Wang Yun] Chinese Acad Sci, Inst Geochem, Guiyang 550002, Peoples R China.;[Xu Xiao-Kai; Zhang Yu-Gui] Henan Polytech Univ, Inst Coalbed Gas Geol, Jiaozuo 454003, Peoples R China.

对采自不同地区和煤矿的六种不同变质程度煤样进行常温常压条件下的超声测量.测量发现:煤的纵波与横波速度均与密度存在良好的线性正相关关系,且沿煤层走向、倾向和垂直煤层层理方向的纵横波速度逐渐降低;走向、倾向和垂向上的纵波速度与同一方向的横波速度也存在良好的线性正相关性;六种煤样三个方向间的速度各向异性一般都大于10%.通过与经典经验公式—Gardner与Castagna公式理论换算值的对比发现:由于煤层的软岩特征,理论换算煤的纵波速度、横波速度与实验室实测值之间存在较大误差.因此,在煤田地震勘探中应使用根据煤的岩石物理测试而形成的关系式.

1995

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2013

0.0

邓华锋, 原先凡, 李建林, 等. 饱水度对砂岩纵波波速及强度影响的试验研究[J]. 岩石力学与工程学报, 2013, 32(8): 1625-1631.

In the correlation research of rock saturation degree，longitudinal wave velocity and strength，the influences of saturation process and air-drying process on strength and longitudinal wave velocity are lack of comprehensive consideration；however，the study of these problems is of great significance for ultrasonic technology in the testing of rock physico-mechanical parameters. Based on these，typical layered sandstones in the Three Gorges reservoir area were selected，vertical-bedding samples and parallel-bedding samples were prepared to conduct saturation and air-drying experiment. The experimental results show that：(1) The relationship between longitudinal wave velocity and saturation degree is obviously nonlinear and nonmonotonic；the longitudinal wave velocity of water-bearing rock is not only related to saturation degree，but also associated with saturation process and air-drying process. (2) The anisotropy of sandstone is obvious；the longitudinal wave velocity change range of vertical-bedding rock is significantly greater than that of the parallel-bedding rock in the process of saturation and air-drying；and the anisotropic characteristics of the sandstone increase slightly under saturated state. (3) In the process of saturation and air-drying，the changing laws of compressive strength and longitudinal wave velocity are inconsistent. The adsorbed water which is on the surface of mineral particles and pore wall has a great influence on elastic modulus and strength；however，the influence of pore saturation degree on longitudinal wave velocity is more apparent. These research results have important reference value for the strength and longitudinal wave velocity tests of water-bearing rock；what?s more，the relevant test methods can provide reference for similar test.

(1. Collaborative Innovation Center for Geo-hazards and Eco-environment in Three Gorges Area，China Three Gorges University，Yichang，Hubei 443002，China；2. Key Laboratory of Geological Hazards on Three Gorges Reservoir Area of Ministry of Education，China Three Gorges University，Yichang，Hubei 443002，China)

在岩石饱水度、纵波波速及强度的相关性研究中，较少综合地考虑饱水、风干过程及各向异性对岩样纵波波速、强度的影响，而这些问题的研究对于超声技术在岩石物理力学参数测试中具有重要的意义。基于此，选取三峡库区典型层状砂岩，制备垂直层理和平行层理两种岩样，进行岩样的饱水和风干试验。试验结果表明：(1) 岩样的纵波波速与饱水度具有明显非线性、非单调的关系，含水岩样的纵波波速不仅与饱水度的大小有关，而且与饱水、风干过程有关。(2) 砂岩各向异性明显，在饱水和风干过程中，垂直层理岩样纵波波速的变化幅度明显大于平行层理岩样，饱水后，砂岩的各向异性特征略有增强。(3) 在饱水、风干过程中，岩样的抗压强度和纵波波速存在变化规律不一致的现象，岩石矿物颗粒表面和孔壁的吸附水对岩样的弹性模量和强度影响较大，而岩石孔隙内的饱水程度对纵波波速的影响更为明显。研究成果对含水岩石的强度、波速测试分析具有较好的参考价值，同时，相关试验方法也可以为类似试验提供参考。

2006

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2009

0.0

刘向君, 刘洪, 徐晓雷, 等. 低孔低渗砂岩加载条件下的声波传播特性实验研究[J]. 岩石力学与工程学报, 2009, 28(3): 560-567.

Based on the rock mechanical experiment on low porosity and low permeability sandstone under different confining pressures and synchronous collecting experiments of transit time intervals of longitudinal and transverse waves and wave patterns of those rocks，the behaviors of acoustic velocity，amplitude and frequency spectrum properties under triaxial and uniaxial loadings are studied. The following conclusions can be drawn. (1) The velocity and frequency spectrum properties of longitudinal and transverse waves change with rock deformation and failure stages. In the stage of fracture and pore compaction inside rock，the velocities of the longitudinal and transverse waves increase rapidly. The ratio of axial stress corresponding to peak velocity of longitudinal and transverse waves to compressive strength of rock decreases as the arithmetic product of porosity and permeability increases. (2) The changes of longitudinal and transverse waves patterns are closely related to rock deformation. As the axial load increases，the fractures in rock generate and develop；when the axial stress reaches 60% of the limit strength，obvious scattered wave signal appears at the end of the transverse wave pattern. (3) As the axial load increases，rock is compacted，and the amplitude of frequency spectrum curve increases as well. When the axial load increases further，the fractures will appear in rock；and low frequency signal is more active than the high frequency one in frequency spectrum curve. (4) In the stage before rock strength reaches peak value，both the first arrival wave amplitude and the principal amplitude tend to increase. In the stage of elastic compression，the two kinds of amplitudes increase rapidly，while in the stage of unsteady fracture expansion，the principal amplitude tends to increase more slowly than the first arrival wave amplitude. It is of theoretical and practical significance to predict rock fracture and its long-term stability.

以低孔低渗砂岩在不同围压条件下的岩石力学测试实验及力学实验过程中岩石纵、横波时差和波形等的采集实验为基础，研究低孔低渗砂岩在三轴和单轴加载过程中声波波速、幅度、频谱特性的变化特征。研究发现：(1) 低孔低渗砂岩的声波纵、横波速及频谱特性随岩石变形和破坏的阶段变化而变化。在岩石中裂隙、孔洞压密阶段，纵、横波波速都快速上升；纵、横波速达到峰值时的轴向应力与岩石抗压强度的比值随孔隙度与渗透率乘积的增大而减小。(2) 声波纵、横波波形的变化与岩石的变形紧密相关。随着轴向载荷增大，岩石内部裂纹的产生和扩展，当岩石轴向应力为极限强度的60%左右时，横波波形末端出现明显的散射波信号。(3) 随着轴向载荷增大，岩石被压实，频谱曲线上的振幅呈增大趋势；随着岩石轴向载荷进一步增加，裂纹产生，频谱曲线上低频端较高频端活跃。(4) 岩石达到峰值强度前阶段，纵波首波振幅和频谱主振幅都表现出上升趋势，且弹性压缩阶段，首波振幅和频谱主振幅上升速率较快，裂纹不稳定扩展阶段，主振幅表现出比首波振幅低的上升趋势。低孔低渗砂岩加载过程中表现出来的声波传播特性的变化特征，对其内部裂缝动态变化的预测和稳定性评价都具有重要的指导意义。

2009

0.0

2014

0.0

吴基文, 沈书豪, 翟晓荣, 等. 煤层底板注浆加固效果波速探查与评价[J]. 物探与化探, 2014, 38(6): 1302-1306.

The grouting reinforcement of the coal seam floor and the construction of aquifers are effective methods in preventing and controlling of karstic water disaster in the coal seam floor above the confined aquifer during safe mining.In order to evaluate the effect of grouting reinforcement in the coal seam floor, the authors set the Ⅱ615 working face of the Hengyuan coal mine in northern Anhui Province as the study object and selected normal regions as well as abnormal regions.In addition,wave velocity detection was conducted for floor rocks before and after grouting in each region respectively by logging with seismic wave in drill holes.The results show that there is a considerable difference in wave velocity between the normal and abnormal regions before grouting,and the wave velocities in the two regions are basically the same after grouting.The wave velocity of floor sandstone strata rises obviously after grouting and it is 1.2 times the wave velocity before grouting.However,the wave velocities of marine mudstone change only insignificantly before and after grouting, which is in accordance with the completeness of rock core and non-guide rise exposed by drill holes.All this fully indicates that grouting could play a good role in the reinforcement of crack rocks.

1. School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China; 2. Wanbei Coal-Electricity Group Co., Ltd., Suzhou 234000, China; 3. Huainan Ming Group Corp. Ltd., Huainan 232001, China

底板注浆加固与含水层改造是承压水体上煤层安全开采底板岩溶水害防治的有效方法之一。为了评价煤层底板注浆加固效果,以皖北恒源煤矿Ⅱ615工作面为研究对象,采用钻孔震波检层法,选择正常区域和异常区域,分别对各区域注浆前后底板岩体进行了波速探测,结果表明:注浆前,正常、异常区域波速存在较大差异,注浆后两者基本一致;注浆后底板砂岩段岩层波速增加明显,约为注浆前的1.20倍,而海相泥岩段注浆前后波速变化不大,这与钻孔揭露岩芯的完整性和底板水无上升现象一致,充分说明注浆对裂隙岩体起到了很好的加固作用。

2008

0.0

尤明庆, 苏承东, 立小双. 损伤岩石试样的力学特性与纵波速度关系研究[J]. 岩石力学与工程学报, 2008, 27(3): 458-467.

The longitudinal wave velocity was used to review the mechanical properties of marble specimens which were compressed under confining pressure and coarse sandstone specimens which were heated to various temperatures. Rock is not a kind of linear elastic material. The longitudinal wave velocity，Young¢s modulus and strength are different macroscopical behaviors of rock mechanical properties. There is a clear inverse correlation between strength and longitudinal wave velocity of specimens. It can be explained as that marble has been compressed by geostresses and the lower strength in a local place would result in the lower stress on the material neighborhood and better contact among crystals. Marble specimen was damaged continuously during compression under confining pressure while the bearing capacity keeps constant. The damage in specimen changes with confining pressure and axial deformation. The longitudinal wave velocity，uniaxial strength and Young¢s modulus of damage specimens only have a positive statistic correlation roughly，but there are some exceptions. Sandstone is made of mineral particles and cement. The cement will be weakened after heated，which results in the decrease of longitudinal wave velocity and initial modulus. But thermal deformation may improve the contact state of mineral particles departed by fissure，so the average modulus is nearly the same and strength becomes higher before temperature increases to 500 ℃，after that the average modulus and strength decrease with temperature.

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。

2006

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王大兴, 辛可锋, 李幼铭, 等. 地层条件下砂岩含水饱和度对波速及衰减影响的实验研究[J]. 地球物理学报, 2006, 49(3): 908-914.

To study the influence of the gas saturata to seismic wave propagation, at the temperature and pressure of stratum, the velocity and attenuation Q of primary and share waves in Changqing sandstone samples are measured under different saturation degrees by ultrasonic. The result shows that under the high frequency condition, fluid contents in sandstone samples have nearly no effect on share wave velocity, but affects obviously primary wave velocity; and the relation between fluid content and wave attenuation is different for Swave and Pwave. The analysis to the experiment result and the corresponding influence mechanism is made, and an application example is presented.

1 School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049， China 2 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029，China 3 Research Institute of E & D, Changqing OilField Company, Xi'an 710021，China

为了研究含气地层对地震波传播的影响，在地层温压条件下，用超声波测试了长庆油田苏里格气田砂岩样品在不同饱和度下的纵、横波速度和衰减Q值.实验表明砂岩样品的物性和流体含量对纵波的速度和衰减的影响均大于横波,含气饱和度大于60％时纵波Q值变化明显；物性越好，含气饱和度越高，纵波Q值越小，吸收越大.分析实验结果和相应的影响机理，给出了利用纵波的吸收衰减预测砂岩含气性的应用实例.

2006

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赵群, 郝守玲. 煤样的超声速度和衰减各向异性测试实例[J]. 地球物理学进展, 2006, 21(2): 531-534.

The technique of impulse transmission can process colleced samples of coal bed into two kinds of models(22 entries 10 side style and 2 entries 20 side style) which can be used in ultrasonic testing of compression wave and shear wave. According to ultrasonic testing results, Velocity anisotropy、shear wave splitting and attenuation anisotropy are caused by the existence of directional arrangement of fractures in the coal samples. At one time, we have found evidently the dynamics characters of compression wave than the kinematics one, and compression wave attenuation with azimuth changes of fractures are evidently high shear wave. Therefore, it offers reliable experiment foundation for detecting and predicting fractures by using compression wave attributes changes.

我们利用脉冲传输技术对某一煤层采集的岩样，加工成两类模型（22个8面体和两个20面柱体样品）做超声P波和S波测试.测试分析结果表明：煤样中定向排列的裂隙存在产生明显的速度各向异性、横波分裂和衰减各向异性.同时还发现纵波的动力学特征变化比运动学特征更明显，纵波衰减随裂隙方位的变化明显大于横波.这为利用纵波属性的变化进行裂隙检测和预测提供可靠实验依据.

... 从目前研究的现状来看,以往对于岩体超声波的研究涉及较多的主要为岩性较为均质的火成岩 6,1819,对于非均质程度较高的沉积岩尤其是煤体的物理力学性质的研究较少,目前对于煤体超声特性的研究大多反应围压对煤岩超声响应特征的影响^[20],而对轴压对煤岩超声响应特征的影响鲜有报道 ...

2009

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... 品质因子Q值采用振幅衰减法^[21]进行计算: ...