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Min ZHANG, Guojun CAI, Wentang ZHENG. Experimental Research on Dynamic Characteristic Parameters of Soft Rock Foundation in a Nuclear Power Plant[J]. SOUTHERN ENERGY CONSTRUCTION, 2019, 6(2): 99-105. doi: 10.16516/j.gedi.issn2095-8676.2019.02.018
Citation: Min ZHANG, Guojun CAI, Wentang ZHENG. Experimental Research on Dynamic Characteristic Parameters of Soft Rock Foundation in a Nuclear Power Plant[J]. SOUTHERN ENERGY CONSTRUCTION, 2019, 6(2): 99-105. doi: 10.16516/j.gedi.issn2095-8676.2019.02.018
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Experimental Research on Dynamic Characteristic Parameters of Soft Rock Foundation in a Nuclear Power Plant

doi: 10.16516/j.gedi.issn2095-8676.2019.02.018
  • 1.

    China Energy Engineering Group Guangdong Electric Power Design Institute Co., Ltd., Guangzhou 510663, China

  • 2.

    State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu 610059, China

  • 3.

    National Geological Engineering Experimental Teaching Demonstration Center of Chengdu University of Technology, Chengdu 610059, China

  • Received Date: 2018-10-16
  • Rev Recd Date: 2019-02-15
  • Publish Date: 2020-07-11
  •   [Introduction]  Cycle load has effect on the rock strength and mechanical characteristics and China still lack the research on dynamic characteristic parameter of mechanism of medium weathering sandstone.  [Method]  According to test physical parameters of 90 medium weathering sandstones, the deep and velocity of sonic were presented as power founction, then MTS machine was used to conduct cyclic load test in different amplitude obtain the sample′s law of hysteretic cycle, dynamic elastic modulus, axial strain and damping ratio in axial cyclic load.  [Result]  The results show that the velocity is increasing with the increasing of the depth. The density of sample approximate 2.50 g/cm3. The axial strain and plastic displacement are increasing with the increasing of rounds. The increasing area of hysteretic cycle means that rock inner cracks is creating continuously resulting to increasing consumption of energy.The form of hysteretic cycle is same as sharp leaf and what it′s sharp but not around in the time of increasing stress or decreasing stress means that the sample reflection of changing stress is rapid and the plastic displacement in the time of changing stress is little relatively. The dynamic elastic modulus is increasing and damping ratio is decreasing with the increasing of dynamic strain. The math relations between either elastic modulus or damping and dynamic strain is presented as linear. The correlation coefficient R2 is almost above 0.85 showing good relevance.  [Conclusion]  This work provides some guidance for further study on testing and evaluation of dynamic characteristic parameters for soft rock foundation of nuclear power plant.
  • [1] 王旭宏，胡继华，耿学勇，等. 吉阳核电厂古近系软岩现场剪切试验及成果分析 [C]// 中国地质学会工程地质专业委员会.全国工程地质学术年会2015，长春，2015. 长春：中国地质学会工程地质专业委员会，2015.
    [2] 付丽丽，丁鹏飞. 高密度电阻率法在核电勘察中的应用[J]. 华北水利水电大学学报(自然科学版), 2011, 32(3): 99-101.

    FU L L, DING P F. Application of high-density resistivity method in nuclear power investigation [J]. Journal of North China Institute of Water Conservancy and Hydroelectric Power(Natural Sciences), 2011, 32(3): 99-101.
    [3] YUN S J, PALAZOTTO A. Plastic deformation under cyclic loading using two-back stress hardening models [J]. International Journal of Fatigue，2008，30(3): 473-482.
    [4] SHALEV E, LYAKHOVSKY V, OUGIERSIMONIN A，et al. Inelastic compaction dilation and hysteresis of sandstones under hydrostatic conditions [J]. Geophysical Journal International，2014，197(2): 920-925.
    [5] 郭印同，赵克烈，孙冠华，等. 周期荷载下盐岩的疲劳变形及损伤特性研究 [J]．岩土力学，2011，32(5): 1353-1359.

    GUO Y T, ZHAO K L, SUN G H，et al. Experimental study of fatigue deformation and damage characteristic of salt rock under cyclic loading [J]. Rock and Soil Mechanics，2011，32(5): 1353-1359.
    [6] 刘建锋，翟俨伟，裴建良，等. 不同频率循环荷载下大理岩动力学特性试验研究 [J]. 河南理工大学学报(自然科学版)，2014，33(4): 432-436.

    LIU J F, ZHAI Y W, PEI J L，et al. Experimental study on dynamic characteristic of marble specimens under cyclic loading with different frequencies [J]. Journal of Henan Polytechnic University(Natural Science)，2014，33(4): 432-436.
    [7] 肖建清，冯夏庭，丁德馨，等. 常幅循环荷载作用下岩石的滞后及阻尼效应研究 [J]. 岩石力学与工程学报，2010，29(8): 1677-1683.

    XIAO J Q, FENG X T, DING D X，et al. Study of hysteresis and damping effects of rock subjected to constant amplitude cyclic loading [J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(8): 1677-1683.
    [8] 朱明礼，朱珍德，李刚，等. 循环荷载作用下花岗岩动力特性试验研究 [J]. 岩石力学与工程学报，2009，28(12): 2520-2526.

    ZHU M L, ZHU Z D, LI G，et al. Experimental study of dynamic characteristics of granite under cyclic loading [J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(12): 2520-2526.
    [9] 朱珍德，孙林柱，王明洋. 不同频率循环荷载作用下岩石阻尼比试验与变形破坏机制细观分析 [J]. 岩土力学，2010，31(增刊1): 8-12.

    ZHU Z D, SUN L Z, WANG M Y. Damping ratio experiment and mesomechanical analysis of deformation failure mechanism on rock under different frequency cyclic loadings [J]. Rock and Soil Mechanics, 2010，31(Supp.1): 8-12.
    [10] 蒋新兴，朱珍德，石崇，等. 彭泽核电厂砂岩动力学试验研究 [J]. 河海大学学报(自然科学版)，2011，39(1): 78-83.

    JIANG X X, ZHU Z D, SHI C, et al. Experimental study on sandstone dynamics of Pengze Nuclear Power Plant [J]. Jouranl of Hohai University(Natural Sciences), 2011，39(1): 78-83.
    [11] 葛修润，蒋宇，卢允德，等. 周期荷载作用下岩石疲劳变形特性试验研究 [J]. 岩石力学与工程学报，2003，22(10): 1581-1585.

    GE X R, JIANG Y, LU Y D，et al. Testing study on fatigue deformation law of rock under cyclic loading [J]. Chinese Journal of Rock Mechanics and Engineering，2003，22(10): 1581-1585.
    [12] 王者超，赵建纲，李术才，等. 循环荷载作用下花岗岩疲劳力学性质及其本构模型 [J]. 岩石力学与工程学报，2012，31(9): 1888-1900.

    WANG Z C, ZHAO J G, LI S C, et al. Fatigue mechanical behavior of granite subjected to cyclic load and its constitutive model [J]. Chinese Journal of Rock Mechanics and Engineering, 2012, 31(9): 1888-1900.
    [13] 刘恩龙，黄润秋，何思明. 循环加载时围压对岩石动力特性的影响 [J]. 岩土力学，2011，32(10): 3009-3013.

    LIU E L, HUANG R Q, HE S M. Influence of confining pressure on dynamic properties of rock samples subjected to cyclic loading [J]. Rock and Soil Mechanics, 2011，32(10): 3009-3013.
    [14] 杨永杰，宋扬，楚俊. 循环荷载作用下煤岩强度及变形特征试验研究 [J]. 岩石力学与工程学报，2007，27(1): 201-205.

    YANG Y J, SONG Y, CHU J. Experimental study on characteristics of strength and deformation of coal under cyclic loading [J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 27(1): 201-205.
    • 通讯作者: 陈斌, bchen63@163.com
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Experimental Research on Dynamic Characteristic Parameters of Soft Rock Foundation in a Nuclear Power Plant

doi: 10.16516/j.gedi.issn2095-8676.2019.02.018
  • 1. China Energy Engineering Group Guangdong Electric Power Design Institute Co., Ltd., Guangzhou 510663, China
  • 2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu 610059, China
  • 3. National Geological Engineering Experimental Teaching Demonstration Center of Chengdu University of Technology, Chengdu 610059, China
  • Received Date: 2018-10-16
  • Rev Recd Date: 2019-02-15
  • Publish Date: 2020-07-11

Abstract:   [Introduction]  Cycle load has effect on the rock strength and mechanical characteristics and China still lack the research on dynamic characteristic parameter of mechanism of medium weathering sandstone.  [Method]  According to test physical parameters of 90 medium weathering sandstones, the deep and velocity of sonic were presented as power founction, then MTS machine was used to conduct cyclic load test in different amplitude obtain the sample′s law of hysteretic cycle, dynamic elastic modulus, axial strain and damping ratio in axial cyclic load.  [Result]  The results show that the velocity is increasing with the increasing of the depth. The density of sample approximate 2.50 g/cm3. The axial strain and plastic displacement are increasing with the increasing of rounds. The increasing area of hysteretic cycle means that rock inner cracks is creating continuously resulting to increasing consumption of energy.The form of hysteretic cycle is same as sharp leaf and what it′s sharp but not around in the time of increasing stress or decreasing stress means that the sample reflection of changing stress is rapid and the plastic displacement in the time of changing stress is little relatively. The dynamic elastic modulus is increasing and damping ratio is decreasing with the increasing of dynamic strain. The math relations between either elastic modulus or damping and dynamic strain is presented as linear. The correlation coefficient R2 is almost above 0.85 showing good relevance.  [Conclusion]  This work provides some guidance for further study on testing and evaluation of dynamic characteristic parameters for soft rock foundation of nuclear power plant.

Min ZHANG, Guojun CAI, Wentang ZHENG. Experimental Research on Dynamic Characteristic Parameters of Soft Rock Foundation in a Nuclear Power Plant[J]. SOUTHERN ENERGY CONSTRUCTION, 2019, 6(2): 99-105. doi: 10.16516/j.gedi.issn2095-8676.2019.02.018
Citation: Min ZHANG, Guojun CAI, Wentang ZHENG. Experimental Research on Dynamic Characteristic Parameters of Soft Rock Foundation in a Nuclear Power Plant[J]. SOUTHERN ENERGY CONSTRUCTION, 2019, 6(2): 99-105. doi: 10.16516/j.gedi.issn2095-8676.2019.02.018
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  • 我国大部分滨海核电厂的核岛、泵房等重要的核安全相关物项(抗震Ⅰ类)，都选择在中等～微风化的硬质火成岩地基上，其特点为核岛持力层大多为微风化及新鲜火成岩，其特点是强度高、剪切波速值高(>1 100 m/s)、静态承载力大(>1.0 MPa)、动态响应以高频响应为主、地基振动周期短、地震能量传导快、地基与基础为刚性接触等特点，为I类厂址；随着核电事业的不断发展，在厂址其他资源条件都十分理想或很难找到合适的基岩厂址的情况下，可借鉴国外建设非基岩厂址的经验，目前国内也尝试了沉积岩地基(防城港核电)及半成岩地基(如吉阳核电古近系软岩[1]和松滋核电马峪河厂址下第三系软岩[2])，并开始研究非硬质岩地基。

    核电站地基岩体在工程中不仅要承受自然界稳定的荷载，还要承受工程施工过程中的爆破，工程机械的往复运动和地震等的往复荷载。这些往复的荷载会影响岩石的强度和力学性质，使得岩体的稳定性大打折扣，因此需研究循环荷载下的岩石应力应变和力学参数变化规律。以往的研究表明，在循环荷载下，材料在不同因素下表现为不同力学行为[3]。样品内部的原生结构、围压、加载的应力幅值、还有频率等均为影响岩石的动力特征的因素。Eyal Shalev等人[4]根据不同幅值砂岩的循环加载试验，对加卸载过程中的幅值对体应变、体积模量的影响及滞回效应进行了分析；郭印同等人[5]研究发现岩石疲劳破坏的过程在提高平均应力的大小和循环荷载上限应力时会受到显著影响；刘建锋等人[6]根据不同频率和幅值的循环荷载试验，获得了幅值和频率对大理岩动弹模和动泊松比的影响规律；肖建清[7]、朱明理[8]、朱珍德[9,10]等学者通过循环荷载试验得到了岩石的阻尼参数，讨论了阻尼特性。葛修润等[11]根据循环荷载试验，研究了岩石的疲劳门槛值和不可逆变形；王者超等[12]根据花岗岩的三轴循环荷载试验，研究了花岗岩的力学特征并提出了疲劳力学模型；刘恩龙等[13]针对砂岩探讨了在不同围压的作用下循环加载时砂岩的动力力学性质，并研究了围压对砂岩的动力力学性质的影响；杨永杰等[14]对煤岩在循环荷载作用下强度、变形以及疲劳损伤过程进行了研究。目前，对核电工程应用中的风化砂岩的动态参数研究相对较少。

    本文以某核电厂软岩地基中等风化砂岩相关物理参数统计，得出物理参数与深度的规律，随后进行循环荷载试验，得出中等风化砂岩的动力学参数并对参数的特征进行分析，进而确立其动态参数的规律，并在某核电工程中应用示范。

1　试验条件

    1.1　试样准备

  • 本次试验的样品为中等风化砂岩，按照国际岩石力学的制样标准，将岩石制成高100 mm±1 mm直径50 mm±1 mm的圆柱标准样。

    • 1.2　循环荷载实验设备

  • 试验设备为美国进口的MTS三轴试验机，为目前最先进的室内岩石力学试验设备，如图1所示。该试验机进行的振动试验，振动频率达3 Hz以上，振动波形可为三角波、正弦波、斜波、方波及随机波，振动相位差可在0～2 π任意设定，具有多种控制模式，并可在试验过程中进行多种控制模式间的任意转换。

    Figure 1.  MTS rock triaxial test machine

2　物理参数统计

  • 本次测试了90个中等风化砂岩试样取样深度、波速以及密度，并将取样深度与波速以及密度的关系绘制如图2和图3所示。

    Figure 2.  Graphic of relation of deeps and sonic velocity of sandstone

    Figure 3.  Graphic of relation of deeps and density of sandstone

    根据图2，以上90个砂岩波速数据汇总得拟合曲线y＝1 199.05x0.308，砂岩的波速和深度满足幂函数关系，随着深度的增加，砂岩的波速也随之增加，并且在深度较低时(40 m内)，砂岩的波速的离散性较大，浮动范围为1 500～4 000 m/s，但随着深度的增加，波速的离散性与低深度相比较为减少，基本在拟合曲线附近波动。根据图3，以上90个中等风化砂岩密度数据汇总可知，该砂岩的密度基本在2.50 g/cm3附近波动，低深度砂岩的密度离散性较大，在2.34～2.60 g/cm3波动，而随着深度的逐渐增加，密度的离散性在逐渐减少，基本稳定在2.50 g/cm3左右。

3　动三轴试验设计及分析

    3.1　试验方案

  • 挑选三组中等风化砂岩进行单轴循环荷载试验，通过单轴试验得到该中等风化砂岩的单轴抗压强度范围在6.55 MPa～12.64 MPa之间，单轴循环荷载时，每一个试样分8次进行振动频率为1 HZ的动应力加载循环，每级动应力的下限为1 MPa，动应力上限分别为每一组测得的单轴抗压强度的10%、20%、30%、40%、50%、60%、70%、80%。每次加载幅值循环30次，加载方式为先加到第一级应力，然后循环30次，待循环完成后将力回到应力下限继续加下一级应力。

    • 3.2　试验原理

  • 岩石为非理想弹性体，动应力与动应变波形线在时间上并不完全对应，有时间差，在动应力-动应变曲线上表现为卸载段曲线不沿原加载段曲线返回，卸载段低于加载段，于是，会出现滞回环现象，如图4所示。

    Figure 4.  The hysteretic cycle in cyclic loading process

    岩石在振动加、卸载过程中能量损失的大小根据滞回环ABC的面积的大小得出，动弹性模量Ed的大小根据滞回环的平均斜率得出，4倍的三角形AOD的面积反映了一个循环中所储存的弹性应变能。文中动弹性模量和阻尼比的公式为：

    ((1))
    ((2))
    ((3))

    式中：σdmax为一次循环荷载中岩样所受到的最大的应力；σdmin为一次循环荷载中岩样所受到的最小的应力；εd1是每次循环荷载开始时试样的轴向应变量；εd2是每次循环荷载结束时试样的轴向应变量；εdm为εd1和εd2的中间应变；εdmax是每次循环荷载加到最大值时试样的轴向最大应变量。

    • 3.3　滞回环形态分析

  • 三组试样施加8级应力荷载时，动应力与动应变关系图如图5,图6图7所示。

    Figure 5.  ZFS-1 curves of relation of dynamic stress and strain

    Figure 6.  ZFS-2 curves of relation of dynamic stress and strain

    Figure 7.  ZFS-3 curves of relation of dynamic stress and strain

    施加每一级应力荷载时，开始相邻滞回环的间距相对较大，说明一开始试样内部裂隙较多，较为松散，随着应力荷载级数增加随着循环的次数增加，试样轴向应变在不断增加，试样的塑性变形不断增大，反映试样在受到循环荷载作用，从松散到压密到开始破坏的过程。随着应力幅值的增大，滞回环的面积逐渐增加，试样循环所消耗的能量逐渐增大，试样内部裂隙不断扩展发育，引起能量损耗增加。

    每级应力循环20次的动应力与动应变示意图如图8,图9,图10图10所示，由图，滞回环的形态皆为尖叶状，在应力减少或者增加的转折点处滞回曲线呈尖状而非圆状，说明试样对应力的变化反应迅速，并且在应力转折时试样的塑性应变较小。

    Figure 8.  ZFS-1 curves of relation of dynamic stress and strain at 20 rounds

    Figure 9.  ZFS-2 curves of relation of dynamic stress and strain at 20 rounds

    Figure 10.  ZFS-3 curves of relation of dynamic stress and strain at 20 rounds

    • 3.4　动弹性模量和阻尼比分析

  • 如图11,图12,图13,图14,图15图16所示，取每级动应力加载阶段25次的滞回环进行动弹性模量计算和阻尼比计算制作动弹性模量与应变以及阻尼比与应变关系图。

    Figure 11.  ZFS-1 relation of dynamic elastic modulus and strain

    Figure 12.  ZFS-2 relation of dynamic elastic modulus and strain

    Figure 13.  ZFS-3 relation of dynamic elastic modulus and strain

    Figure 14.  ZFS-1 relation of damping ratio and strain

    Figure 15.  ZFS-2 relation of damping ratio and strain

    Figure 16.  ZFS-3 relation of damping ratio and strain

    动应变增加，则动弹模减少，阻尼比增加。通过上图求出动弹性模量以及阻尼比拟合关系曲线如表1所示，动弹性模量与动应变呈线性递减关系，阻尼比与动应变呈线性递增关系。拟合曲线相关系数R基本在0.92以上，具有良好相关性。

    编　号 拟合曲线 相关系数
    ZFS-1 E d＝39.05-7.5εd 0.96
    λ＝0.001 2-0.001 1εd 0.96
    ZFS-2 E d＝16.83-1.44εd 0.92
    λ＝0.012-0.004 6εd 0.98
    ZFS-3 E d＝17.51-0.72εd 0.92
    λ＝0.009 8-0.003 9εd 0.86

    Table 1.  Relation of dynamic elastic modulus, damping ratio and strain

    试样在受到循环应力荷载作用时，内部的微裂纹会随着循环应力的变化而变化，具体表现为每次加荷载时内部裂纹会被压密，而卸荷载时裂纹会扩张，从而使得一次循环试样所消耗的能量增加，表现为滞回环面积增加，并且在应力不断循环过程中，其微裂隙会继续扩展，导致不可逆的变形逐渐增加，表现为轴向塑性变形逐渐增加，试样强度降低，从而其动弹性模量降低、阻尼比增加。

4　结论

  • 本次试验根据90个中等风化砂岩的相关试验分析统计，以及典型的三组砂岩试样的单轴循环荷载试验得到了如下结论：

    1)中等风化砂岩的波速和深度满足幂函数关系，随着深度的增加，砂岩的波速也随之增加，并且在深度较低时，砂岩的波速的离散性较大，但随着深度的增加，波速的离散性与低深度相比较为减少，基本在拟合曲线附近波动。

    2)中等风化砂岩的密度基本在2.50 g/cm3附近波动，并且低深度砂岩的密度离散性较大，随着深度的逐渐增加，密度的离散性在逐渐减少，基本稳定。

    3)动应变增加，则动弹模减少，阻尼比增加。动弹性模量与动应变呈幂函数关系，阻尼比与动应变呈线性关系。拟合曲线相关系数R基本在0.92以上，具有良好相关性。

    4)试样在受到循环应力荷载作用时，内部裂纹伴随着压密以及扩张过程，使得循环过程试样所消耗的能量增加，反映为滞回环面积增加。循环过程中，微裂隙持续扩展，导致不可逆的变形逐渐增加，反映为轴向塑性变形逐渐增加，导致其动弹性模量降低、阻尼比增加。

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