冻融循环下堆石料变形特性与抗剪强度试验研究
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摘要
反复的冻融循环是在严寒地区影响高土石坝安全的重要问题。本文依托西藏澜沧江如美高心墙堆石坝工程,利用清华大学研制的堆石料风化试验仪,对如美筑坝堆石料进行了不同法向应力条件下的冻融循环试验和直剪试验,研究了冻融循环过程中堆石料的变形与强度特性。试验结果表明,在一个冻融循环周期内,堆石料试样会依次经历"融缩"—"冻缩"—"冻胀"3个典型状态。冻融循环后会使堆石料试样产生较大的回胀变形,可使试样的密实度和抗剪强度有所降低。20次冻融循环后可使试样的就机抗剪强度降低约11.5%到15.4%。
Freeze-thaw cycling is an important factor affecting the safety of high earth-rock dams in severe cold regions. This paper presents the results of freeze-thaw cycling tests on the rockfill materials of the Rumei project, a high core wall rockfill dam on the Lancang River, Tibet. We conducted the tests using rockfill weathering test apparatus developed by Tsinghua University, together with direct shear tests under the conditions of different normal stress. Deformation and strength characteristics of the rockfill materials under freeze-thaw cycling were then examined. Test results show that during a given freezethaw cycle, a rockfill sample undergoes three typical stages: thaw shrinking, frost shrinking, and frost heaving. On completion of the freeze-thaw cycles, the sample starts a large back expansion deformation,reducing its compactness and shear strength. The reduction in shear strength is about 11.5% to 15.4% in the case of 20 freeze-thaw cycles.
Freeze-thaw cycling is an important factor affecting the safety of high earth-rock dams in severe cold regions. This paper presents the results of freeze-thaw cycling tests on the rockfill materials of the Rumei project, a high core wall rockfill dam on the Lancang River, Tibet. We conducted the tests using rockfill weathering test apparatus developed by Tsinghua University, together with direct shear tests under the conditions of different normal stress. Deformation and strength characteristics of the rockfill materials under freeze-thaw cycling were then examined. Test results show that during a given freezethaw cycle, a rockfill sample undergoes three typical stages: thaw shrinking, frost shrinking, and frost heaving. On completion of the freeze-thaw cycles, the sample starts a large back expansion deformation,reducing its compactness and shear strength. The reduction in shear strength is about 11.5% to 15.4% in the case of 20 freeze-thaw cycles.
引文
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[14]胡田飞,刘建坤,常丹,等.冻融循环对粉质黏土力学性质的影响及邓肯-张模型[J].中国公路学报,2018,31(2):298-307.HU Tianfei,LIU Jiankun,CHANG Dan,et al.Influence of freeze-thaw cycling on mechanical properties of silty clay and duncan-chang constitutive model[J].China Journal of Highway and Transport,2018,31(2):298-307.(in Chinese)
[15]KONRAD J-M,SAMSON M.Hydraulic conductivity of kaolinite-silt mixtures subjected to closed-system freezing and thaw consolidation[J].Canadian Geotechnical Journal,2000,37(4):857-869.
[16]SIMONSEN E,ISACSSON U.Soil behavior during freezing and thawing using variable and constant confining pressure triaxial tests[J].Canadian Geotechnical Journal,2001,38(4):863-875.
[17]LI G,MA W,ZHAO S,et al.Effect of freeze-thaw cycles on mechanical behavior of compacted fine-grained soil[J].Cold Regions Engineering,2012:72-81.
[18]TANG L,TIAN S,LING X,et al.Effect of freeze-thaw cycles on the strength of base course materials used under China’S high-speed railway line[J].Journal of Cold Regions Engineering,2017,31(4):06017003.
[19]VIKLANDER P.Permeability and volume changes in till due to cyclic freeze/thaw[J].Canadian Geotechnical Journal,1998,35(3):471-477.
[20]LEE J,LEE D,PARK D,et al.Effect of freezing and thawing on K0 geostatic stress state for granular materials[J].Granul Matter,2016,18(3):68-80.
[2]王海俊,殷宗泽.堆石料长期变形的室内试验研究[J].水利学报,2007,38(8):914-919.WANG Haijun,YIN Zongze.Experimental study on deformation of rockfill material due to long term cyclic wetting-drying[J].Journal of Hydraulic Engineering,2007,38(8):914-919.(in Chinese)
[3]WANG H J,YIN Z Z.Experimental Study on long-time deformation of rockfill under wetting-drying cycle effect[J].Journal of Disaster Prevention and Mitigation Engineering,2012,32(4):488-493.
[4]孙国亮,孙逊,张丙印.堆石料风化试验仪的研制及应用[J].岩土工程学报,2009,31(9):1462-1466.SUN Guoliang,SUN Xun,ZHANG Bingyin.Development and application of weathering test apparatus for rockfill[J].Chinese Journal of Geotechnical Engineering,2009,31(9):1462-1466.(in Chinese)
[5]张其光,张丙印,孙国亮,等.堆石料风化过程中的抗剪强度特性[J].水力发电学报,2016,35(11):112-119.ZHANG Qiguang,ZHANG Bingyin,SUN Guoliang,et al.Shear strength characteristic of weathering rockfill[J].Journal of Hydroelectric Engineering,2016,35(11):112-119.(in Chinese)
[6]孙国亮,张丙印,张其光,等.不同环境条件下堆石料变形特性的试验研究[J].岩土力学,2010,31(5):1413-1419.SUN Guoliang,ZHANG Bingyin,ZHANG Qiguang,et al.Experimental study of deformation characteristics of rockfill under different environmental conditions[J].Rock and Soil Mechanics,2010,31(5):1413-1419.(in Chinese)
[7]石北啸,蔡正银,陈生水.温度变化对堆石料变形影响的试验研究[J].岩土工程学报,2016,38(S2):299-305.SHI Beixiao,CAI Zhengyin,CHEN Shengshui.Experiments on influence of temperature on deformation of rockfills[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):299-305.(in Chinese)
[8]齐吉琳,马巍.冻土的力学性质及研究现状[J].岩土力学,2010,31(1):133-143.QI Jilin,MA Wei.State-of-art of research on mechanical properties of frozen soils[J].Rock and Soil Mechanics,2010,31(1):133-143.(in Chinese)
[9]CHAMBERLAIN E J,GOW A J.Effect of freezing and thawing on the permeability and structure of soils[J].Geotechnical Engineering,1979,13(1):73-92.
[10]QI J,VERMEER P A,CHENG G.A review of the influence of freeze-thaw cycles on soil geotechnical properties[J].Permafrost and Periglacial Processes,2006,17(3):245-252.
[11]张英,邴慧,杨成松.基于SEM和MIP的冻融循环对粉质黏土强度影响机制研究[J].岩石力学与工程学报,2015,34(S1):3597-3603.ZHANG Ying,BING Hui,YANG Chengsong.Influences of freeze-thaw cycles on mechanical porperties of silty clay based on sem and mip test[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(S1):3597-3603.(in Chinese)
[12]王大雁,马巍,常小晓,等.冻融循环作用对青藏粘土物理力学性质的影响[J].岩石力学与工程学报,2005,24(23):4313-4319.WANG Dayan,MA Wei,CHANG Xiaoxiao,et al.Physicomechanical properties changes of Qinghai-Tibet clay due to cyclic freezing and thawing[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(23):4313-4319.(in Chinese)
[13]常丹,刘建坤,李旭,等.冻融循环对青藏粉砂土力学性质影响的试验研究[J].岩石力学与工程学报,2014,33(7):1496-1502.CHANG Dan,LIU Jiankun,LI Xu,et al.Experiment study of effects of freezing-thawing cycles on mechanical properties of qinghat-tibet silty sand[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(7):1496-1502.(in Chinese)
[14]胡田飞,刘建坤,常丹,等.冻融循环对粉质黏土力学性质的影响及邓肯-张模型[J].中国公路学报,2018,31(2):298-307.HU Tianfei,LIU Jiankun,CHANG Dan,et al.Influence of freeze-thaw cycling on mechanical properties of silty clay and duncan-chang constitutive model[J].China Journal of Highway and Transport,2018,31(2):298-307.(in Chinese)
[15]KONRAD J-M,SAMSON M.Hydraulic conductivity of kaolinite-silt mixtures subjected to closed-system freezing and thaw consolidation[J].Canadian Geotechnical Journal,2000,37(4):857-869.
[16]SIMONSEN E,ISACSSON U.Soil behavior during freezing and thawing using variable and constant confining pressure triaxial tests[J].Canadian Geotechnical Journal,2001,38(4):863-875.
[17]LI G,MA W,ZHAO S,et al.Effect of freeze-thaw cycles on mechanical behavior of compacted fine-grained soil[J].Cold Regions Engineering,2012:72-81.
[18]TANG L,TIAN S,LING X,et al.Effect of freeze-thaw cycles on the strength of base course materials used under China’S high-speed railway line[J].Journal of Cold Regions Engineering,2017,31(4):06017003.
[19]VIKLANDER P.Permeability and volume changes in till due to cyclic freeze/thaw[J].Canadian Geotechnical Journal,1998,35(3):471-477.
[20]LEE J,LEE D,PARK D,et al.Effect of freezing and thawing on K0 geostatic stress state for granular materials[J].Granul Matter,2016,18(3):68-80.