冻结饱水砂卵石三轴压缩强度试验研究
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摘要
为研究北京富水砂卵石地层冻结后的强度特性,以北京某地铁暗挖车站砂卵石为研究对象,进行不同温度(-5、-10、-15、-20℃),不同围压(0.0、0.3、0.8、1.3、2.0、3.0、4.0、8.0 MPa)条件下三轴压缩试验。试验结果表明:冻结砂卵石的应力-应变曲线以应变软化形态为主,高负温、高围压条件下,呈现理想塑性破坏形态;砂卵石强度、黏聚力和摩擦角均随温度降低而增大,其中强度呈指数分布,黏聚力和摩擦角呈线性分布;强度和弹性模量随围压增加而增大,但增大趋势逐渐减小,低围压压缩区强度满足线性Morh-Coulomb(简称M-C)准则;冻结砂卵石的破坏形态以破裂面始/终于试样侧面的剪切破坏为代表,张拉型破坏受冰影响显著,仅存在于低围压条件下,高围压、高负温时易出现体胀型破坏。
This paper investigates the strength characteristics of water-rich sandy gravel subjected to freezing, as this soil is often encountered in Beijing. A series of triaxial compression tests has been performed on sandy gravel samples obtained at mining station of Beijing Metro at different temperatures(-5℃,-10℃,-15℃,-20℃) and confining pressures(0.0、0.3、0.8、1.3、2.0、3.0、4.0 MPa and 8.0 MPa).The results show that: the behavior of frozen sandy gravel is dominated by strain softening, and the ideal plastic failure mode occurs only when the soil experiences high negative temperature and confining pressure; the strength, cohesion and friction angle of the soil all increase with the decrease of temperature. The variation of strength with temperature satisfies an exponential distribution, while the changes in cohesion and friction angle follow a linear relationship; the strength and elastic modulus of frozen sandy gravel increase as the confining pressure increases, but the increasing rate descends gradually. The Mohr-Coulomb criterion can still be used effectively to characterize the soil's compressive response at low confining pressure. The failure mode of frozen sandy gravel is represented by shear failure with diagonal fractures on the lateral sides of the specimen. Tensile failure occurs when the specimen is subjected to a low confining pressure, and it is influenced by the formation of ice significantly. The mechanism of volumetric inflation has been found when a high level of temperature and confining pressure is applied to the specimen.
This paper investigates the strength characteristics of water-rich sandy gravel subjected to freezing, as this soil is often encountered in Beijing. A series of triaxial compression tests has been performed on sandy gravel samples obtained at mining station of Beijing Metro at different temperatures(-5℃,-10℃,-15℃,-20℃) and confining pressures(0.0、0.3、0.8、1.3、2.0、3.0、4.0 MPa and 8.0 MPa).The results show that: the behavior of frozen sandy gravel is dominated by strain softening, and the ideal plastic failure mode occurs only when the soil experiences high negative temperature and confining pressure; the strength, cohesion and friction angle of the soil all increase with the decrease of temperature. The variation of strength with temperature satisfies an exponential distribution, while the changes in cohesion and friction angle follow a linear relationship; the strength and elastic modulus of frozen sandy gravel increase as the confining pressure increases, but the increasing rate descends gradually. The Mohr-Coulomb criterion can still be used effectively to characterize the soil's compressive response at low confining pressure. The failure mode of frozen sandy gravel is represented by shear failure with diagonal fractures on the lateral sides of the specimen. Tensile failure occurs when the specimen is subjected to a low confining pressure, and it is influenced by the formation of ice significantly. The mechanism of volumetric inflation has been found when a high level of temperature and confining pressure is applied to the specimen.
引文
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[18]尹珍珍,陈有亮,王鹏.上海人工冻结黏土单轴无侧限抗压强度试验研究[J].岩土力学,2012,33(3):788-792.YIN Zhen-zhen,CHEN You-liang,WANG Peng.Uniaxial unconfined compressive strength test on artificially frozen clay in Shanghai[J].Rock and Soil Mechanics,2012,33(3):788-792.
[19]单仁亮,白瑶,随顺猛,等.淡水冰三轴压缩力学特性试验研究[J].应用基础与工程科学学报,2018,26(4):901-917.SHAN Ren-liang,BAI Yao,SUI Shun-meng,et al.Experimental research on mechanical characteristics of freshwater ice under triaxial compression[J].Journal of Basic Science and Engineering,2018,26(4):901-917.
[20]单仁亮,白瑶,黄鹏程,等.三向受力条件下淡水冰破坏准则研究[J].力学学报,2017,49(2):467-477.SHAN Ren-liang,BAI Yao,HUANG Peng-cheng,et al.Experimental research on failure criteria of freshwater ice under triaxial compressive stress[J].Chinese Journal of Theoretical and Applied Mechanics,2017,49(2):467-477.
[2]杜海民,马巍,张淑娟,等.应变率与含水率对冻土单轴压缩特性影响研究[J].岩土力学,2016,37(5):1373-1379.DU Hai-min,MA Wei,ZHANG Shu-juan,et al.Effects of strain rate and water content on uniaxial compressive characteristics of frozen soil[J].Rock and Soil Mechanics,2016,37(5):1373-1379.
[3]赵晓东,周国庆,陈国舟.温度梯度冻结黏土破坏形态及抗压强度分析[J].岩土工程学报,2010,32(12):1854-1860.ZHAO Xiao-dong,ZHOU Guo-qing,CHEN Guo-zhou.Failure modes and compression strength of frozen clay under thermal gradient[J].Chinese Journal of Geotechnical Engineering,2010,32(12):1854-1860.
[4]牛亚强,王旭,廖孟柯,等.冻结改良黄土三轴强度和变形特性试验研究[J].岩土工程学报,2016,38(增刊2):198-203.NIU Ya-qiang,WANG Xu,LIAO Meng-ke,et al.Experimental study on triaxial strength and deformation characteristics of frozen-improved loess[J].Chinese Journal of Geotechnical Engineering,2016,38(Supp.2):198-203.
[5]EVIRGEN BURAK,TUNCAN MUSTAFA,TUNCANAHMET.Stress-strain characteristics of frozen silty and clayey soils[C]//Proceedings of the 25th International Ocean and Polar Engineering Conference.[S.l.]:[s.n.],2015:1798-1802.
[6]马巍,吴紫汪,盛煜.围压对冻土强度特性的影响[J].岩土工程学报,1995,17(5):7-11.MA Wei,WU Zi-wang,SHENG Yu.Effect of confining pressure on strength behaviour of frozen soil[J].Chinese Journal of Geotechnical Engineering,1995,17(5):7-11.
[7]YAMAMOTO YUKO,SPRINGMAN SARAH M.Axial compression stress path tests on artificial frozen soil samples in a triaxial device at temperatures just below0℃[J].Canadian Geotechnical Journal,2014,51(10):1178-1195.
[8]GE Xiao-xuan,YANG Zhao-hui,STILL Benjamin.Mechanical properties of naturally frozen ice-rich silty soils[J].New Astronomy,2013,36:19-25.
[9]YANG Yu-gui,LAI Yuan-ming,CHANG Xiao-xiao,et al.Laboratory and theoretical investigations on the deformation and strength behaviors of artificail frozen soil[J].Cold Regions Science and Technology,2010,64(1):39-45.
[10]马巍,吴紫汪,张长庆.冻土的强度与屈服准则[J].冰川冻土,1993,15(1):129-133.MA Wei,WU Zi-wang,ZHANG Chang-qing.Strength and yield criteria of frozen soil[J].Journal of Glaciology and Geocryology,2001,15(1):129-133.
[11]胡凯,赖远明.含盐冻结粉质砂土的强度参数和强度准则试验研究[J].冰川冻土,2014,36(5):1199-1204.HU Kai,LAI Yuan-ming.Experimental study on the strength parameters and strength criteria of saline frozen silty sand[J].Journal of Glaciology and Geocryology,2014,36(5):1199-1204.
[12]马玲,齐吉琳,余帆,等.冻结砂土三轴试验中颗粒破碎研究[J].岩土工程学报,2015,37(3):544-550.MA Ling,QI Jin-lin,YU Fan,et al.Particle crushing of frozen sand under triaxial compression[J].Chinese Journal of Geotechnical Engineering,2015,37(3):544-550.
[13]赵晓东,周国庆,李生生.不同温度梯度冻结中砂加卸荷变形特性研究[J].中国矿业大学学报,2010,39(2):158-162.ZHAO Xiao-dong,ZHOU Guo-qing,LI Sheng-sheng.Deformation properties of frozen sand during loading and unloading in the presence of a thermal gradient[J].Journal of China University of Mining&Technology,2010,39(2):158-162.
[14]中华人民共和国水利部.GB/T 50123-1999土工试验方法标准[S].北京:中国计划出版社,1999.The Ministry of Water Resources of the People’s Republic of China.GB/T 50123-1999 Standard for soil test method[S].Beijing:China Planning Press,999.
[15]国家安全生产监督管理总局.MT/T 593.1-2011人工冻土物理力学性能试验[S].北京:煤炭工业出版社,2011.State Administration of Work Safety.MT/T 593.1-2011Artificial frozen soil physics mechanics performance test[S].Beijing:China Coal Industry Publishing House,2011.
[16]单仁亮,杨昊,郭志明,等.负温饱水红砂岩三轴压缩强度特性试验研究[J].岩石力学与工程学报,2014,33(增刊2):3657-3664.SHAN Ren-liang,YANG Hao,GUO Zhi-ming,et al.Experimental study of strength characters of saturated red sandstone on negative temperature under triaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Supp.2):3657-3664.
[17]单仁亮,郭志明,刘校东,等.低温冻结岩土三轴试验机的改进研究[J].煤炭工程,2015,47(4):96-98.SHAN Ren-liang,GUO Zhi-ming,LIU Xiao-dong,et al.Improvement of low-temperature permafrost triaxial testing machine[J].Coal Engineering,2015,47(4):96-98.
[18]尹珍珍,陈有亮,王鹏.上海人工冻结黏土单轴无侧限抗压强度试验研究[J].岩土力学,2012,33(3):788-792.YIN Zhen-zhen,CHEN You-liang,WANG Peng.Uniaxial unconfined compressive strength test on artificially frozen clay in Shanghai[J].Rock and Soil Mechanics,2012,33(3):788-792.
[19]单仁亮,白瑶,随顺猛,等.淡水冰三轴压缩力学特性试验研究[J].应用基础与工程科学学报,2018,26(4):901-917.SHAN Ren-liang,BAI Yao,SUI Shun-meng,et al.Experimental research on mechanical characteristics of freshwater ice under triaxial compression[J].Journal of Basic Science and Engineering,2018,26(4):901-917.
[20]单仁亮,白瑶,黄鹏程,等.三向受力条件下淡水冰破坏准则研究[J].力学学报,2017,49(2):467-477.SHAN Ren-liang,BAI Yao,HUANG Peng-cheng,et al.Experimental research on failure criteria of freshwater ice under triaxial compressive stress[J].Chinese Journal of Theoretical and Applied Mechanics,2017,49(2):467-477.