圆饼状高压实膨润土膨胀力各向异性特征研究
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摘要
针对作为我国缓冲/回填材料的高压实高庙子膨润土,采用自主研制的膨胀力-渗透性一体化测试仪器开展膨胀力试验,分别测定圆饼状试样的轴向膨胀力和径向膨胀力发展规律,研究试样初始干密度、初始吸力和尺寸效应对其膨胀力各向异性特征的影响。试验结果显示,轴向膨胀力和径向膨胀力均随着试样初始干密度的增加呈指数增大,膨胀力各向异性特征愈加显著。轴向膨胀力和径向膨胀力均随着试样初始吸力的增加而呈减小趋势;相同初始吸力条件下,径向膨胀力均大于轴向膨胀力,但是膨胀力各向异性系数随着初始吸力增大而不断减小。试样尺寸对膨胀力有显著影响,增加试样高度,轴向膨胀力不断增加,径向膨胀力增加到某一数值后不再随高度增加,膨胀力各向异性系数随着试样高度的增加逐渐减小。最后,基于膨润土膨胀机理、压实效应和尺寸效应,分析了膨胀力各向异性特征的形成机理。
In China, Gaomiaozi(GMZ) bentonite has been selected as the first choice of buffer/backfill materials for high-level radioactive waste repository. In order to investigate the anisotropic characteristics of swelling pressure for compacted GMZ bentonite, a series of swelling pressure tests were conducted by a self-developed apparatus on the pie-shaped block specimens to measure the axial and radial swelling pressure, and then the effects of initial dry density, initial suction and dimension on the anisotropy were analyzed. The results show that with the increase of the initial dry density, the axial swelling pressure and radial swelling pressure exponentially increase, and the anisotropy of swelling pressure tends to be more obvious. Both the axial and radial swelling pressures decrease with the increase of the initial suction of the specimen; for the same initial suction, the radial swelling pressure is greater than the axial swelling pressure; moreover, the anisotropy coefficient decreases as the initial suction increases. Meanwhile, swelling pressure is remarkably affected by specimen dimension, because with the increase of specimen height, the axial swelling pressure increases gradually, while the radial swelling pressure increases and remains constant until a certain value is reached; therefore, the anisotropy coefficient gradually reduces as the height increases. Furthermore, the anisotropy mechanism of the swelling pressure was analyzed based on the swelling process, compaction effect and size effect.
In China, Gaomiaozi(GMZ) bentonite has been selected as the first choice of buffer/backfill materials for high-level radioactive waste repository. In order to investigate the anisotropic characteristics of swelling pressure for compacted GMZ bentonite, a series of swelling pressure tests were conducted by a self-developed apparatus on the pie-shaped block specimens to measure the axial and radial swelling pressure, and then the effects of initial dry density, initial suction and dimension on the anisotropy were analyzed. The results show that with the increase of the initial dry density, the axial swelling pressure and radial swelling pressure exponentially increase, and the anisotropy of swelling pressure tends to be more obvious. Both the axial and radial swelling pressures decrease with the increase of the initial suction of the specimen; for the same initial suction, the radial swelling pressure is greater than the axial swelling pressure; moreover, the anisotropy coefficient decreases as the initial suction increases. Meanwhile, swelling pressure is remarkably affected by specimen dimension, because with the increase of specimen height, the axial swelling pressure increases gradually, while the radial swelling pressure increases and remains constant until a certain value is reached; therefore, the anisotropy coefficient gradually reduces as the height increases. Furthermore, the anisotropy mechanism of the swelling pressure was analyzed based on the swelling process, compaction effect and size effect.
引文
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[15]刘泉声,王志俭.砂-膨润土混合物膨胀力影响因素的研究[J].岩石力学与工程学报,2002,21(7):1054-1058(Liu Quansheng,Wang Zhijian.Influence factors of sand-bentonite mixtureson the swelling pressure[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(7):1054-1058(in Chinese))
[16]刘月妙,徐国庆,刘淑芬,等.我国高放废物处置库缓冲/回填材料压实膨胀特性研究[J].铀矿地质,2001,17(1):44-47(Liu Yuemiao,Xu Guoqing,Liu Shufen,et al.Study on compactibility and swelling property of buffer/backfill material for HLW repository[J].Uranium Geology,2001,17(1):44-47(in Chinese))
[17]Schanz T,Al-Badran Y.Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01[J].Soils and Foundations,2014,54(4):748-759
[18]Villar M V,Lloret A.Influence of dry density and water content on the swelling of a compacted bentonite[J].Applied Clay Science,2008,39(1-2):38-49
[19]Sun D,Sun W,Fang L.Swelling characteristics of Gaomiaozi bentonite and its prediction[J].Journal of Rock Mechanics and Geotechnical Engineering,2014,6(2):113-118
[20]Saba S,Cui Y J,Tang A M,et al.Investigation of the swelling behaviour of compacted bentonite-sand mixture by mock-up tests[J].Canadian Geotechnical Journal,2014,51(12):1399-1412
[21]Wang Q,Tang A M,Cui Y J,et al.Experimental study on the swelling behaviour of bentonite/claystone mixture[J].Engineering Geology,2012,124:59-66
[22]Saiyouri N,Tessier D,Hicher P Y.Experimental study of swelling in unsaturated compacted clays[J].Clay Minerals,2004,39(4):469-479
[23]Massat L,Cuisinier O,Bihannic I,et al.Swelling pressure development and inter-aggregate porosity evolution upon hydration of a compacted swelling clay[J].Applied Clay Science,2016:124-125,197-210
[24]Lee J O,Lim J G,Kang I M,et al.Swelling pressures of compacted Ca-bentonite[J].Engineering Geology,2012,129:20-26
[25]Yang T,Knutsson S,Liu X D.Swelling properties and permeability of expandable clays of potential use for nuclear waste disposal[J].Journal of Earth Sciences and Geotechnical Engineering,2016,6(2):49-61
[26]Mitchell J K,Soga K.Fundamentals of soil behavior[M].3rd Edition.New Jersey:John Wiley&Sons,2005
[27]Bouchelaghem F,Jozja N.Multi-scale study of permeability evolution of a bentonite clay owing to pollutant transport part I:model derivation[J].Engineering Geology,2009,108(1-2):119-132
[2]Cui Y J.On the hydro-mechanical behaviour of MX80bentonite-based materials[J].Journal of Rock Mechanics and Geotechnical Engineering,2017(9):565-574
[3]Chen Y G,Cui Y J,Tang A M,et al.A preliminary study on hydraulic resistance of bentonite/host-rock seal interface[J].Geotechnique,2014,64(12):997-1002
[4]陈宝,陈建琴,曹永超.接缝对高压实膨润土工程屏障自封闭性能的影响[J].岩石力学与工程学报,2012,31(3):618-624(Chen Bao,Chen Jianqin,Cao Yongchao Influence of joint on self-sealing behaviour of highly compacted bentonite in engineering barrier[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(3):618-624(in Chinese))
[5]Sun D A,Zhang J Y,Zhang J R,et al.Swelling characteristics of GMZ bentonite and its mixtures with sand[J].Applied Clay Science,2013(83-84):224-230
[6]谢云,陈正汉,孙树国,等.重塑膨胀土的三向膨胀力试验研究[J].岩土力学,2007,28(8):1636-1642(Xie Yun,Chen Zhenghan,Sun Shuguo,et al.Test research on three-dimensional swelling pressure of bentonite clay[J].Rock and Soil Mechanics,2007,28(8):1636-1642(in Chinese))
[7]谢云,陈正汉,李刚,等.南阳膨胀土三向膨胀力规律研究[J].后勤工程学报,2006(1):11-14(Xie Yun,Chen Zhenghan,Li Gang,et al.Test research on three-dimensional swelling pressure of Nanyang expansive soil[J].Journal of Logistical Engineering University,2006(1):11-14(in Chinese))
[8]秦冰,陈正汉,刘月妙,等.高庙子膨润土GMZ001三向膨胀力特性研究[J].岩土工程学报,2009,31(5):756-763(Qin Bing,Chen Zhenghan,Liu Yuemiao,et al.Characteristics of 3D swelling pressure of GMZ001bentonite[J].Chinese Journal of Geotechnical Engineering,2009,31(5):756-763(in Chinese))
[9]汪龙,方祥位,申春妮,等.膨润土-砂混合材料三向膨胀力试验研究[J].地下空间与工程学报,2015,11(4):940-945(Wang Long,Fang Xiangwei,Shen Chunni,et al.Three-dimensional swelling pressure characteristic of bentonite-sand mixtures[J].Chinese Journal of Underground Space and Engineering,2015,11(4):940-945(in Chinese))
[10]孙发鑫,陈正汉,秦冰,等.高庙子膨润土-砂混合料的三向膨胀力特性[J].岩石力学与工程学报,2013,32(1):200-207(Sun Faxin,Chen Zhenghan,Qin Bing,et al.Characteristics of three-dimensional swelling pressure of GMZ bentonite-sand mixture[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(1):200-207(in Chinese))
[11]胡畔,杨庆.膨润土加砂混合物膨胀特征试验研究[J].岩土力学,2012,33(2):453-458(Hu Pan,Yang Qing.Experimental study of swelling characteristics of bentonite-sand mixture[J].Rock and Soil Mechanics,2012,33(2):453-458(in Chinese))
[12]Saba S,Barnichon J,Cui Y,et al.Microstructure and anisotropic swelling behaviour of compacted bentonite/sand mixture[J].Journal of Rock Mechanics and Geotechnical Engineering,2014,6(2):126-132
[13]马利科,刘月妙.高庙子膨润土膨胀力影响因素研究[C]//第三届废物地下处置学术研讨会论文集,2010(Ma Like,Liu Yuemiao.Research on influence factors of swelling pressure of GMZ bentonite[C]//Symposium of the 3rd waste underground disposal seminar,2010(in Chinese))
[14]叶为民,Schanz T,钱丽鑫,等.高压实高庙子膨润土GMZ01的膨胀力特征[J].岩石力学与工程学报,2007,26(S2):3861-3865(Ye Weimin,Schanz T,Qian Lixin,et al.Characteristics of swelling pressure of densely compacted GaoMiaoZi bentonite[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(S2):3861-3865(in Chinese))
[15]刘泉声,王志俭.砂-膨润土混合物膨胀力影响因素的研究[J].岩石力学与工程学报,2002,21(7):1054-1058(Liu Quansheng,Wang Zhijian.Influence factors of sand-bentonite mixtureson the swelling pressure[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(7):1054-1058(in Chinese))
[16]刘月妙,徐国庆,刘淑芬,等.我国高放废物处置库缓冲/回填材料压实膨胀特性研究[J].铀矿地质,2001,17(1):44-47(Liu Yuemiao,Xu Guoqing,Liu Shufen,et al.Study on compactibility and swelling property of buffer/backfill material for HLW repository[J].Uranium Geology,2001,17(1):44-47(in Chinese))
[17]Schanz T,Al-Badran Y.Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01[J].Soils and Foundations,2014,54(4):748-759
[18]Villar M V,Lloret A.Influence of dry density and water content on the swelling of a compacted bentonite[J].Applied Clay Science,2008,39(1-2):38-49
[19]Sun D,Sun W,Fang L.Swelling characteristics of Gaomiaozi bentonite and its prediction[J].Journal of Rock Mechanics and Geotechnical Engineering,2014,6(2):113-118
[20]Saba S,Cui Y J,Tang A M,et al.Investigation of the swelling behaviour of compacted bentonite-sand mixture by mock-up tests[J].Canadian Geotechnical Journal,2014,51(12):1399-1412
[21]Wang Q,Tang A M,Cui Y J,et al.Experimental study on the swelling behaviour of bentonite/claystone mixture[J].Engineering Geology,2012,124:59-66
[22]Saiyouri N,Tessier D,Hicher P Y.Experimental study of swelling in unsaturated compacted clays[J].Clay Minerals,2004,39(4):469-479
[23]Massat L,Cuisinier O,Bihannic I,et al.Swelling pressure development and inter-aggregate porosity evolution upon hydration of a compacted swelling clay[J].Applied Clay Science,2016:124-125,197-210
[24]Lee J O,Lim J G,Kang I M,et al.Swelling pressures of compacted Ca-bentonite[J].Engineering Geology,2012,129:20-26
[25]Yang T,Knutsson S,Liu X D.Swelling properties and permeability of expandable clays of potential use for nuclear waste disposal[J].Journal of Earth Sciences and Geotechnical Engineering,2016,6(2):49-61
[26]Mitchell J K,Soga K.Fundamentals of soil behavior[M].3rd Edition.New Jersey:John Wiley&Sons,2005
[27]Bouchelaghem F,Jozja N.Multi-scale study of permeability evolution of a bentonite clay owing to pollutant transport part I:model derivation[J].Engineering Geology,2009,108(1-2):119-132