冻融循环作用下饱水砂岩的强度劣化模型
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摘要
为研究冻融循环作用下饱水砂岩的强度劣化规律,开展了饱水条件下两组具有不同初始孔隙率砂岩的室内冻融循环试验。在测量砂岩孔隙率变化量、静态峰值强度和动态峰值强度的基础上,分析了整个冻融循环次数内两组砂岩孔隙率变化量和峰值强度损失率的演化规律。采用孔隙率变化量来衡量岩石的冻融损伤,比较了两组砂岩的冻融损伤程度大小。基于孔隙率变化量建立了饱水砂岩在冻融循环作用下的相对剩余峰值强度劣化模型,并选取与饱水砂岩强度劣化模型相同的函数对试验数据进行了拟合验证。结果表明:在整个冻融循环次数内,两组砂岩的孔隙率变化量和峰值强度损失率均随着冻融循环次数的增加而增大。B组砂岩的冻融损伤程度大于A组砂岩,但其峰值强度损失率却低于A组砂岩,说明饱水砂岩的峰值强度受冻融循环次数与应变率共同影响,且二者影响机制相反。冻融循环作用下饱水砂岩相对剩余峰值强度与孔隙率变化量的拟合关系较好,表明冻融前后的孔隙率变化量适用于评估饱水砂岩冻融作用后的相对剩余峰值强度。
To study the strength deterioration rules of saturated sandstone under freeze-thaw cycles, laboratory freeze-thaw tests were carried out on two groups of sandstone with different initial porosities under water saturation. On the basis of measuring the porosity variation, static peak strength and dynamic peak strength, the evolution law of porosity variation and loss rate of peak strength were analyzed within the whole freeze-thaw cycles. The extent of freeze-thaw damage was compared between the two groups sandstone by using the porosity variation to measure freeze-thaw damage. A relative residual peak strength deterioration model of saturated sandstone under freeze-thaw cycles was established based on the porosity variation. The same function as the strength deterioration model of saturated sandstone was selected to fit the test data,showing a good correlation. Within the whole freeze-thaw cycles, the porosity variation and loss rate of peak strength increased with the freeze-thaw cycles for two groups of sandstone. Freeze-thaw damage of group B was higher than that of group A, but its loss rate of peak strength was lower than group A, which indicates that the peak strength of saturated sandstone is affected by freeze-thaw cycles and strain rate and this two factors have completely opposite effect mechanism. There exists a good fitting relationship between the relative residual peak strength and the porosity variation of saturated sandstone under freeze-thaw cycles, which shows that the porosity variation before and after freezing-thawing is suitable for evaluating the relative residual peak strength of saturated sandstone after freeze-thaw cycles.
To study the strength deterioration rules of saturated sandstone under freeze-thaw cycles, laboratory freeze-thaw tests were carried out on two groups of sandstone with different initial porosities under water saturation. On the basis of measuring the porosity variation, static peak strength and dynamic peak strength, the evolution law of porosity variation and loss rate of peak strength were analyzed within the whole freeze-thaw cycles. The extent of freeze-thaw damage was compared between the two groups sandstone by using the porosity variation to measure freeze-thaw damage. A relative residual peak strength deterioration model of saturated sandstone under freeze-thaw cycles was established based on the porosity variation. The same function as the strength deterioration model of saturated sandstone was selected to fit the test data,showing a good correlation. Within the whole freeze-thaw cycles, the porosity variation and loss rate of peak strength increased with the freeze-thaw cycles for two groups of sandstone. Freeze-thaw damage of group B was higher than that of group A, but its loss rate of peak strength was lower than group A, which indicates that the peak strength of saturated sandstone is affected by freeze-thaw cycles and strain rate and this two factors have completely opposite effect mechanism. There exists a good fitting relationship between the relative residual peak strength and the porosity variation of saturated sandstone under freeze-thaw cycles, which shows that the porosity variation before and after freezing-thawing is suitable for evaluating the relative residual peak strength of saturated sandstone after freeze-thaw cycles.
引文
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[16]中华人民共和国行业标准编写组.SL264-2001水利水电工程岩石试验规程[S].北京:中国水利水电出版社,2001.The Professional Standards Compilation Group of People’s Republic of China.SL264-2001 Specifications for rock tests in water conservancy and hydroelectric engineering[S].Beijing:China Water&Power Press,2001.
[17]贾海梁,项伟,申艳军,等.冻融循环作用下岩石疲劳损伤计算中关键问题的讨论[J].岩石力学与工程学报,2017,36(2):335-346.JIA Hai-Liang,XIANG Wei,SHEN Yan-jun,et al.Discussion of the key issues within calculation of the fatigue damage of rocks subjected to freeze-thaw cycles[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(2):335-346.
[18]宫凤强,陆道辉,李夕兵,等.不同应变率下砂岩动态强度准则的试验研究[J].岩土力学,2013,34(9):2433-2441.GONG Feng-qiang,LU Dao-hui,LI Xi-bing,et al.Experimental research of sandstone dynamic strength criterion under different strain rates[J].Rock and Soil Mechanics,2013,34(9):2433-2441.
[2]陈国庆,郭帆,王剑超,等.冻融后石英砂岩三轴蠕变特性试验研究[J].岩土力学,2017,38(增刊1):203-210.CHEN Guo-qing,GUO Fan,WANG Jian-chao,et al.Experimental study of creep properties of quartz sandstone after freezing-thawing cycles[J].Rock and Soil Mechanics,2017,38(Suppl.1):203-210.
[3]刘泉声,康永水,黄兴,等.裂隙岩体冻融损伤关键问题及研究状况[J].岩土力学,2012,33(4):971-978.LIU Quan-sheng,KANG Yong-shui,HUANG Xin,et al.Critical problems of freeze-thaw damages in fractured rock and their research status[J].Rock and Soil Mechanics,2012,33(4):971-978.
[4]阎锡东,刘红岩,邢闯锋,等.冻融循环条件下岩石弹性模量变化规律研究[J].岩土力学,2015,36(8):2315-2322.YAN Xi-dong,LIU Hong-yan,XING Chuang-feng,et al.Variability of elastic modulus in rock under freezing-thawing cycles[J].Rock and Soil Mechanics,2015,36(8):2315-2322.
[5]KRAUTBLATTER M,FUNK D,G NZEL F K.Why permafrost rocks become unstable:a rock-ice-mechanical model in time and space[J].Earth Surface Processes&Landforms,2013,38(8):876-887.
[6]RUEDRICH J,KIRCHNER D,SIEGESMUND S.Physical weathering of building stones induced by freeze-thaw action:a laboratory long-term study[J].Environmental Earth Sciences,2011,63(7):1573-1586.
[7]AL-OMARI A,BECK K,BRUNETAUD X,et al.Critical degree of saturation:a control factor of freeze-thaw damage of porous limestones at Castle of Chambord,France[J].Engineering Geology,2015,185(3):71-80.
[8]李杰林.基于核磁共振技术的寒区岩石冻融损伤机理试验研究[D].长沙:中南大学,2012.LI Jie-Lin.Experiment study on deterioration mechanism of rock under the conditions of freezing-thawing cycles in cold regions based on NMR technology[D].Changsha:Central South University,2012.
[9]MOMENI A,ABDILOR Y,KHANLARI G R,et al.The effect of freeze-thaw cycles on physical and mechanical properties of granitoid hard rocks[J].Bulletin of Engineering Geology&the Environment,2016,75(4):1-8.
[10]KHANLARI G,SAHAMIEH R Z,ABDILOR Y.The effect of freeze-thaw cycles on physical and mechanical properties of upper red formation sandstones,central part of Iran[J].Arabian Journal of Geosciences,2015,8(8):5991-6001.
[11]闻磊,李夕兵,吴秋红,等.冻融循环作用下花岗斑岩动载强度研究[J].岩石力学与工程学报,2015,34(7):1297-1306.WEN Lei,LI Xi-bing,WU Qiu-hong,et al.Dynamic strength of granite porphyry under freezing-thawing cycles[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1297-1306.
[12]ZHOU K P,LI B,LI J L,et al.Microscopic damage and dynamic mechanical properties of rock under freeze-thaw environment[J].Transactions of Nonferrous Metals Society of China,2015,25(4):1254-1261.
[13]WANG Peng,XU Jin-yu,LIU Shi,et al.A prediction model for the dynamic mechanical degradation of sedimentary rock after a long-term freeze-thaw weathering:considering the strain-rate effect[J].Cold Region Science Technology,2016,131:16-23
[14]徐光苗,刘泉声.岩石冻融破坏机理分析及冻融力学试验研究[J].岩石力学与工程学报,2005,24(17):3076-3082.XU Guang-miao,LIU Quan-sheng.Analysis of mechanism of rock failure due to freeze-thaw cycling and mechanical testing study of frozen-thawed rocks[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(17):3076-3082.
[15]张继周,缪林昌,杨振峰.冻融条件下岩石损伤劣化机制和力学特性研究[J].岩石力学与工程学报,2008,27(8):1688-1694.ZHANG Ji-zhou,MIAO Lin-chang,YANG Zhen-feng,Research on rock degradation and deterioration mechanisms and mechanical characteristics under cyclic freezing-thawing[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(8):1688-1694.
[16]中华人民共和国行业标准编写组.SL264-2001水利水电工程岩石试验规程[S].北京:中国水利水电出版社,2001.The Professional Standards Compilation Group of People’s Republic of China.SL264-2001 Specifications for rock tests in water conservancy and hydroelectric engineering[S].Beijing:China Water&Power Press,2001.
[17]贾海梁,项伟,申艳军,等.冻融循环作用下岩石疲劳损伤计算中关键问题的讨论[J].岩石力学与工程学报,2017,36(2):335-346.JIA Hai-Liang,XIANG Wei,SHEN Yan-jun,et al.Discussion of the key issues within calculation of the fatigue damage of rocks subjected to freeze-thaw cycles[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(2):335-346.
[18]宫凤强,陆道辉,李夕兵,等.不同应变率下砂岩动态强度准则的试验研究[J].岩土力学,2013,34(9):2433-2441.GONG Feng-qiang,LU Dao-hui,LI Xi-bing,et al.Experimental research of sandstone dynamic strength criterion under different strain rates[J].Rock and Soil Mechanics,2013,34(9):2433-2441.