• Scopus数据库收录期刊
  • 中国科技核心期刊
  • 全国中文核心期刊
  • 美国工程索引(EI)收录期刊

基于主动超声激励的岩石节理刚度分布测量研究

王鹏宇, 杨天娇, 王述红

王鹏宇, 杨天娇, 王述红. 基于主动超声激励的岩石节理刚度分布测量研究[J]. 岩土工程学报, 2024, 46(3): 662-669. DOI: 10.11779/CJGE20221224
引用本文: 王鹏宇, 杨天娇, 王述红. 基于主动超声激励的岩石节理刚度分布测量研究[J]. 岩土工程学报, 2024, 46(3): 662-669. DOI: 10.11779/CJGE20221224
WANG Pengyu, YANG Tianjiao, WANG Shuhong. Measurement of distribution of rock joint stiffness based on active ultrasonic excitation[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(3): 662-669. DOI: 10.11779/CJGE20221224
Citation: WANG Pengyu, YANG Tianjiao, WANG Shuhong. Measurement of distribution of rock joint stiffness based on active ultrasonic excitation[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(3): 662-669. DOI: 10.11779/CJGE20221224

基于主动超声激励的岩石节理刚度分布测量研究  English Version

基金项目: 

国家自然科学基金项目 U1602232

中央高校基本科研业务专项项目 N2101018

江苏省自然科学基金项目 BK20230335

详细信息
    作者简介:

    王鹏宇(1994—),男,讲师,主要从事岩石力学方面的研究工作。E-mail: Pywang@njtech.edu.cn

    通讯作者:

    杨天娇, E-mail: yangtianjiaols@126.com

  • 中图分类号: TU45

Measurement of distribution of rock joint stiffness based on active ultrasonic excitation

  • 摘要: Goodman提出采用节理刚度表征复杂岩石节理面的拓扑行为并为其提供定量值,而无需对节理面的粗糙度、接触面积等参数进行详细测量分析。然而目前对岩石节理刚度的测量仍存在局限,因此,在试验室环境下采用压电陶瓷换能器对完整平板试件和含节理平板试件进行弹性波激励,同时采用三维扫描激光多普测振仪监测平板内弹性波的传播数据。将采集的波场信号数据进行滤波、插值、积分等一系列处理,并基于Schoenberg线性滑移模型计算节理刚度分布,实现岩石节理接触行为的全局参数表征,同时进一步验证了岩石节理全场超声表征的可行性。全场波形数据清晰地揭示了岩石节理界面接触行为,为后续深入探索岩石节理几何形状、孔径、界面性质及其地震特征之间的相互关系奠定了基础。
    Abstract: Goodman proposed to use the joint stiffness to characterize the topological behaviors of complex rock joint interfaces and provide quantitative values for them, without measuring and analyzing the geometric parameters such as roughness and contact area of joint interfaces in detail. However, it is difficult to measure the stiffness of rock joints at present. Therefore, the piezoelectric ceramic transducer is used to excite the elastic waves of the intact granite plate specimen and the cracked granite plate specimen in the laboratory environment. At the same time, the scanning laser Doppder Vibrometer is used to monitor propagation data of the elastic waves in the plate. On this basis, the collected signal data of wave fields are processed by filtering, interpolation, integration, etc., and the distribution of joint stiffness is calculated based on the Schoenberg linear sliding model. Then, the joint stiffness is used to parameterize the contact behaviors of rock joints, which further proves the feasibility of ultrasonic characterization of whole rock joints. By using the full-field waveform data, the interface contact behaviors of rock joints are clearly revealed, which lays a foundation for further exploring the relationship among rock joint geometry, pore sizes, interface properties and seismic characteristics.
  • 中国是全球最大的煤炭生产国,拥有114×109 t的探明总储量,是少数以煤炭为主要能源的国家之一。煤炭需求将从2002年的1308×106 t增加到2030年的2402×106 t。作为最大工业固体废物单一污染材料之一,粉煤灰具有颗粒细、相对质量密度小、空隙率大、易失水的不良工程特点[1-2],粉煤灰作为贮灰场后期子坝主要填料,其强度特性影响着灰坝边坡的稳定性,对施工和运行安全带来重要影响[3-4]。此外,贮灰场通常粉尘污染较为严重(图 1),利用率仅为30%,在环境保护方面引起越来越多关注。

    图  1  贮灰场中粉煤灰固化不良造成的粉尘污染
    Figure  1.  Dust pollution caused by poor solidification of fly ash in the ash storage yard

    微生物具有快速繁殖和灵活代谢的特点,对土体的力学和工程特性也有重要影响。由于粉煤灰特殊的材料特性,采用微生物固化粉煤灰的研究鲜有报道[5-7],对粉煤灰的固化强度效应与机制也知之甚少。

    基于此,本文应用微生物诱导碳酸盐沉淀(MICP)方法,考虑自然蒸发和湿缸养护两种条件,研究了微生物反应机理、强化特性及影响因素,对MICP固化粉煤灰的强度效应与机制进行了系统分析,为粉煤灰的资源化利用和灰场粉尘污染控制积累研究经验。

    粉煤灰取自北京石景山热电厂的龙口灰场,根据《土工试验方法标准:GBT 50123—2019》对基本物理性质进行试验,粉煤灰粒组中大于0.075 mm、0.075~0.005 mm以及小于0.005 mm的含量分别为8.6%,81.2%,10.2%;含水率为2%,干密度为0.85 g/cm3,相对质量密度2.02。

    实测巴氏芽孢杆菌菌液初始OD600为3.70,脲酶活性1.86 mS/cm/min。

    营养盐为CaCl2·2H2O(分子量147.01)和CH4N2O(分子量60.06),由中国国药集团化学试剂有限公司生产,营养盐浓度分别为0.10,0.25,0.50,0.75,1.00,1.25,1.50 mol/L,见表 1

    表  1  不同组别的试样中营养盐浓度及质量
    Table  1.  Nutrient concentration and mass in samples of different groups
    试验组别 浓度 氯化钙 尿素
    a 0.10 1.32 0.54
    b 0.25 3.31 1.35
    c 0.50 6.62 2.70
    d 0.75 9.92 4.05
    e 1.00 13.23 5.41
    f 1.25 16.54 6.76
    g 1.50 19.85 8.11
    下载: 导出CSV 
    | 显示表格

    试验主要依据《水泥土配合比设计规程:JGJ T233—2011》、《公路工程混合料配合比设计与试验技术手册》及《建筑地基处理技术规范:JGJ79—2012》进行。具体试验设计见表 2

    表  2  试验设计
    Table  2.  Experimental design
    组别 营养液浓度/(mol·L-1) 掺比 养护龄期/d
    1 0.10 粉煤灰∶菌液=2∶1 7
    2 0.25 粉煤灰∶菌液=2∶1 7
    3 0.50 粉煤灰∶菌液=2∶1 7
    4 0.75 粉煤灰∶菌液=2∶1 7
    5 1.00 粉煤灰∶菌液=2∶1 7
    6 1.25 粉煤灰∶菌液=2∶1 7
    7 1.50 粉煤灰∶菌液=2∶1 7
    下载: 导出CSV 
    | 显示表格

    考虑保湿缸内和室内两种养护环境,实测保湿缸中养护温度为24℃,湿度75%;自然养护条件下试样放在试验室通风良好窗台上,气象资料显示北京市2018年5月27到6月2日气温最高35℃,最低16℃。

    养护至7 d后,保湿缸中(图 2(a))试样表面情况随营养液浓度不同有明显差异,0.5,0.75 mol/L试样表面分布有较多霉菌斑点,浓度较低或较高情况下表面无明显霉斑分布。自然条件下各组试样表面更为干燥,霉斑分布均不明显(图 2(b))。

    图  2  粉煤灰试样养护情况
    Figure  2.  Maintenance of fly ash sample

    养护至相应龄期后,按《土工试验方法标准:GBT 50123—2019》规定的试验方法、程序开展了无侧限抗压试验,轴向位移速率为1.0 mm/min。

    保湿缸中养护试样的应力应变曲线见图 3,图中微生物固化粉煤灰试样轴向应力达到峰值后随着应变增加而快速降低,均表现出明显的脆性破坏形式。未添加微生物灰样的轴向应力达到峰值后,轴向应力随着应变增加而缓慢降低,脆性破坏表现并不明显。不同营养盐浓度试样无侧限抗压强度存在明显差异,表 3中浓度0.5 mol/L峰值应力最大,为102.58 kPa,该组平均应力为90.78 kPa;浓度为0.1 mol/L峰值应力最小,为27.23 kPa,平均应力为28.10 kPa。浓度0.1,0.25,0.5,0.75,1.00,1.25,1.5 mol/L的各组试样平均峰值应力依次为28.10,64.36,90.78,85.37,71.68,50.98,42.96 kPa,微生物固化粉煤灰试样的峰值应力随营养盐浓度增加表现为先增加再降低。

    图  3  保湿缸养护试样轴向力与轴向位移关系曲线
    Figure  3.  Relationship curve between axial force and axial displacement of wet cylinder maintenance curing samples
    表  3  保湿缸养护条件下试样强度
    Table  3.  Sample strength under curing conditions of wet cylinder maintenance
    营养盐浓度/(mol·L-1) 试样质量/g 峰值应力/kPa 平均峰值应力/kPa 养护前后含水率减少值/%
    0.1 126.3 27.23 28.10 2.03
    126.0 28.98 2.05
    0.25 134.8 68.17 64.36 4.36
    134.2 60.54 3.13
    0.5 139.7 102.58 90.78 8.10
    137.7 78.97 7.84
    0.75 137.1 89.14 85.37 6.29
    137.1 81.61 6.88
    1 134.5 65.11 71.68 7.17
    133.2 78.24 7.60
    1.25 132.9 54.87 50.98 7.79
    130.6 47.09 9.38
    1.5 137.5 35.23 42.96 7.85
    138.1 50.69 7.64
    对照组 133.33 18.90 17.14 16.25
    131.68 15.37 16.28
    下载: 导出CSV 
    | 显示表格

    同等养护条件下,仅掺加水的粉煤灰试样无侧限抗压强度普遍偏低,最大仅18.90 kPa,最小仅15.37 kPa,平均为17.14 kPa,平均峰值应力仅为营养盐浓度0.1,0.25,0.5,0.75,1.00,1.25,1.5 mol/L的61.00%,26.63%,18.88%,20.08%,23.91%,33.62%,39.90%。

    表 3中未添加微生物灰样从初始含水率的50%分别降低了16.25%,16.28%,而添加微生物的试样含水率从50%最大仅降低9.38%(1.25 mol/L),最小仅降低2.03%(0.1 mol/L),试样含水率降低明显偏少,表明微生物反应诱导生成碳酸钙过程中使粉煤灰颗粒联接加强,降低了孔隙率和渗透性,有效减少了试样水分流失,宏观上在灰样中形成了更好保水作用和更低的渗透系数。

    自然条件养护下,无侧限抗压试验得到的应力应变曲线见图 4,微生物固化的粉煤灰试样表现为达到峰值后随着应变增加而缓慢降低,与保湿缸内养护相比,轴向应变2%就出现轴向应力峰值,试样脆性破坏更为明显。未添加微生物的灰样轴向应力峰值后,随着应变增加也快速降低,同样表现为脆性破坏。

    图  4  自然条件养护试样轴向力与轴向位移关系曲线
    Figure  4.  Relationship curve between axial force and axial displacement of natural evaporation curing specimens

    不同营养盐浓度试样无侧限抗压强度峰值强度也存在明显差异,表 4中可以看出,1.0 mol/L浓度的峰值应力最大,为80.35 kPa,该组平均应力为78.06 kPa;浓度为0.5 mol/L峰值应力最小,为25.95 kPa,该组平均应力为36.41 kPa,营养盐浓度为0.5,0.75,1.00,1.25,1.5 mol/L的试样平均峰值应力依次为36.41,49.34,78.06,48.42,46.25 kPa,峰值应力随着营养盐浓度的增加也表现为先增加再降低。同等养护条件下,对照组测得无侧限抗压强度偏低,最大仅21.07 kPa,最小仅16.66 kPa。

    表  4  自然养护条件下试样强度
    Table  4.  Sample strength under natural evaporation curing conditions
    营养盐浓度/(mol·L-1) 试样质量/g 峰值应力/kPa 平均峰值应力/kPa 养护前后含水率减少值/%
    0.5 134.43 25.95 36.41 25.35
    135.2 46.85 25.13
    0.75 140.61 54.96 49.34 23.62
    138.6 43.73 25.32
    1 130.74 80.35 78.06 24.30
    133.54 75.77 23.56
    1.25 133.69 55.50 48.42 24.05
    139.7 41.33 25.37
    1.5 134.41 47.18 46.25 21.94
    135.66 45.33 22.29
    对照组 133.18 21.07 18.87 45.10
    133.00 16.66 45.64
    下载: 导出CSV 
    | 显示表格

    根据沉积岩中黏土矿物和常见非黏土矿物X射线衍射分析方法(SY/T 5163—2010),测得粉煤灰矿物含量如表 5所示。微生物在粉煤灰中产生的碳酸钙为方解石,图 5比较了不同固化条件下方解石含量增加,未经微生物处理的粉煤灰中的方解石含量为7.0%。MICP处理后,方解石含量达到18.9%和15.3%,分别增加了170%和119%。

    表  5  粉煤灰矿物含量
    Table  5.  Mineral content of fly ash
    材料 矿物含量/%
    石英 钾长石 方解石 莫来石 黏土矿物
    对照组 8.8 5.6 7.0 75.3 3.3
    缸湿 7.0 0.5 18.9 71.2 2.4
    自然蒸发 6.0 0.6 15.3 75.2 2.9
    下载: 导出CSV 
    | 显示表格
    图  5  不同养护条件下粉煤灰非黏土矿物X射线衍射光谱对比
    Figure  5.  Comparison of X-ray diffraction spectra of fly ash non clay minerals under different curing conditions

    采用SEM/EDS分析方解石形态,图 6(a)中微生物诱导的碳酸钙晶体在粉煤灰试样不同位置的颗粒中呈不同的形状,短柱状为主(图 6(b))。此外,微生物诱导的碳酸钙粒径接近粉煤灰颗粒粒径,能形成更有效地连接和填充,提高固化强度,EDS分析证实观察到的矿物为碳酸钙(图 6(c))。

    图  6  微生物固化粉煤灰SEM扫描和能谱分析结果
    Figure  6.  SEM scanning and energy spectrum analysis results of microbial solidified fly ash

    (1)微生物在粉煤灰中产生的碳酸钙为方解石,含量从7%最大增加到15.3%。

    (2)MICP湿缸固化条件下,无侧限抗压强度最大提高6.55倍,达97.63 kPa。

    (3)固化强度随营养物浓度的增加表现为先增大后降低,保湿缸和自然蒸发条件下的最佳营养浓度分别为0.5 mol/L和1.0 mol/L。

    (4)微生物固化粉煤灰可以减少内部水分损失,保水效果明显,还具有良好的抑尘应用前景。

  • 图  1   试件表面扫描点分布

    Figure  1.   Distribution of scanning points on surface of specimens

    图  2   激励信号和传播信号对比

    Figure  2.   Comparison of excitation and propagation signals

    图  3   试件固定装置

    Figure  3.   Fixing devices for specimens

    图  4   10 kHz激励作用于S2时完整试件不同时刻的速度场vxvy

    Figure  4.   Velocity fields vx and vy at different moments of intact granite specimen with excitation acting of 10 kHz on S2

    图  5   30 kHz激励作用于S2时完整试件不同时刻的速度场vxvy

    Figure  5.   Velocity fields vx and vy at different moments of intact granite specimen with excitation acting of 30 kHz on S2

    图  6   10 kHz激励作用于S3时含节理试件不同时刻的速度场vxvy

    Figure  6.   Velocity fields vx and vy at different moments of fractured granite specimen with excitation acting of 10 kHz on S3

    图  7   30 kHz激励作用于S3时含节理试件不同时刻的速度场vxvy

    Figure  7.   Velocity fields vx and vy at different moments of fractured granite specimen with excitation acting of 30 kHz on S3

    图  8   扫描点D记录的原始速度以及经过带通滤波器处理之后的速度

    Figure  8.   Original recorded velocities and velocity fields after bandpass filtering at scanming point D

    图  9   信号处理之后的位移场uxuy

    Figure  9.   Displacement fields ux and uy after signal processing

    图  10   累积跳跃位移(m)

    Figure  10.   Displacements of cumulative jump

    图  11   试件中节理几何形状的重建

    Figure  11.   Reconstruction of joint geometry in specimen

    图  12   节理刚度分布

    Figure  12.   Distribution of joint stiffness

  • [1]

    CRAWFORD B R, TSENN M C, HOMBURG J M, et al. Incorporating scale-dependent fracture stiffness for improved reservoir performance prediction[J]. Rock Mechanics & Rock Engineering, 2017, 50: 3349-3359.

    [2]

    MCLASKEY G C, THOMAS A M, GLASER S D, et al. Fault healing promotes high-frequency earthquakes in laboratory experiments and on natural faults[J]. Nature, 2012, 491(7422): 101-104. doi: 10.1038/nature11512

    [3]

    PYRAK-NOLTE L J, NOLTE D D. Frequency dependence of fracture stiffness[J]. Geophysical Research Letters, 2013, 19(3): 325-328.

    [4]

    GOODMAN R E, TAYLOR R L, BREKKE T L A. A model for the mechanics of jointed rock[J]. ASCE Soil Mechanics and Foundation Division Journal, 1968, 99(5): 637-659.

    [5] 唐志成, 王晓川. 不同接触状态岩石节理的剪切力学性质试验研究[J]. 岩土工程学报, 2017, 39(12): 2312-2319. doi: 10.11779/CJGE201712021

    TANG Zhicheng, WANG Xiaochuan. Experimental studies on mechanical behaviour of rock joints with varying matching degrees[J]. Chinese Journal of Geotechnical Engineering, 2017, 39(12): 2312-2319. (in Chinese) doi: 10.11779/CJGE201712021

    [6]

    LANG P S, PALUSZNY A, ZIMMERMAN R W. Evolution of fracture normal stiffness due to pressure dissolution and precipitation[J]. International Journal of Rock Mechanics and Mining Sciences, 2016, 88: 12-22. doi: 10.1016/j.ijrmms.2016.06.004

    [7]

    PYRAK-NOLTE L J, NOLTE D D. Approaching a universal scaling relationship between fracture stiffness and fluid flow[J]. Nature Communications, 2016, 7: 10663. doi: 10.1038/ncomms10663

    [8]

    PETROVITCH C L, PYRAK-NOLTE L J, NOLTE D D. Combined scaling of fluid flow and seismic stiffness in single fractures[J]. Rock Mechanics & Rock Engineering, 2014, 47(5): 1613-1623.

    [9]

    QIAO Y D, ZHANG C, ZHANG L. Numerical simulation of fluid-solid coupling of fractured rock mass considering changes in fracture stiffness[J]. Energy Science & Engineering, 2019, 10: 519-536.

    [10]

    HEDAYAT A, PYRAK-NOLTE L J, BOBET A. Precursors to the shear failure of rock discontinuities[J]. Geophysical Research Letters, 2015, 41(15): 5467-5475.

    [11] 刘日成, 尹乾, 杨瀚清, 等. 恒定法向刚度边界条件下三维粗糙节理面循环剪切力学特性[J]. 岩石力学与工程学报, 2021, 40(6): 1092-1109. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX202106002.htm

    LIU Richeng, YIN Qian, YANG Hanqing, et al. Cyclic shear mechanical properties of 3D rough joint surface under constant normal stiffness(CNS) boundary conditions[J]. Chinese Journal of Rock mechanics and Engineering, 2021, 40(6): 1092-1109. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX202106002.htm

    [12]

    KULATILAKE P, SHREEDHARAN S, SHERIZADEH T, et al. Laboratory estimation of rock joint stiffness and frictional parameters[J]. Geotechnical & Geological Engineering, 2016, 34(6): 1-13.

    [13]

    JIANG Y, XIAO J, TANABASHI Y, Et al. Development of an automated servo-controlled direct shear apparatus applying a constant normal stiffness condition[J]. International Journal of Rock Mechanics & Mining Sciences, 2004, 41(2): 275-286.

    [14]

    NASSIR M A, WAN SETTARI R, et al. Joint stiffness and deformation behaviour of discontinuous rock[J]. The Journal of Canadian Petroleum Technology, 2010, 49(9): 78-86. doi: 10.2118/140119-PA

    [15]

    LI J, QIU Z, ZHONG H, et al. Parametric study on near-wellbore fracture geometry for wellbore strengthening in anisotropic formation[J]. Journal of Petroleum Science and Engineering, 2019, 184: 106549.

    [16]

    HEDAYAT A, PYRAK-NOLTE L J, BOBET A. Detection and quantification of slip along non-uniform frictional discontinuities using digital image correlation[J]. Geotechnical Testing Journal, 2014, 37(5): 1-14.

    [17]

    LUBBE R, WORTHINGTON M H. A field investigation of fracture compliance[J]. Geophysical Prospecting, 2006, 54(3): 319-331. doi: 10.1111/j.1365-2478.2006.00530.x

    [18]

    ACOSTA-COLON A, PYRAK-NOLTE L J, NOLTE D D. Laboratory-scale study of field of view and the seismic interpretation of fracture specific stiffness[J]. Geophysical Prospecting, 2010, 57(2): 209-224.

    [19]

    Schoenberg, Michael. Elastic wave behavior across linear slip interfaces[J]. Journal of the Acoustical Society of America, 1998, 68(5): 1516-1521.

    [20] 邓华锋, 熊雨, 肖瑶, 等. 基于单试件法的节理岩体抗剪强度参数分析[J]. 岩土工程学报, 2020, 42(8): 1509-1515. doi: 10.11779/CJGE202008016

    DENG Huafeng, XIONG Yu, XIAO Yao, et al. Shear strength parameters of jointed rock mass based on single test sample method[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(8): 1509-1515. (in Chinese) doi: 10.11779/CJGE202008016

    [21]

    POURAHMADIAN F, GUZINA B B. On the elastic-wave imaging and characterization of fractures with specific stiffness[J]. International Journal of Solids & Structures, 2015, 71: 126-140.

    [22]

    WANG P, WANG S, ZHANG Z, et al. Reconstruction of fracture geometry in material medium by elastic wave[J]. Construction and Building Materials, 2021, 287(2): 123001.

    [23]

    WANG P, WANG S, YANG T. Spatial distribution of mechanical parameters along a fracture interface[J]. Soil Dynamics and Earthquake Engineering, 2022, 157(5): 107222.

    [24]

    NGUYEN T P, GUZINA B B. Generalized linear sampling method for the inverse elastic scattering of fractures in finite bodies[J]. Inverse Problems, 2019, 35(10): 516-532.

图(12)
计量
  • 文章访问数:  273
  • HTML全文浏览量:  45
  • PDF下载量:  54
  • 被引次数: 0
出版历程
  • 收稿日期:  2022-10-07
  • 网络出版日期:  2024-03-14
  • 刊出日期:  2024-02-29

目录

/

返回文章
返回