定向剪切应力路径下冻结黏土强度特性试验
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摘要
为探索考虑主应力轴方向变化等复杂应力路径下的冻结黏土强度特性,采用冻土空心圆柱仪,在温度为-10℃条件下,对重塑冻结黏土开展一系列主应力轴方向固定不变的定向剪切试验,探讨大主应力轴方向角a、中主应力系数b和平均主应力p值变化对冻结黏土强度特性的影响.通过对广义剪应力-广义剪应变曲线的分析,发现a角和p值变化对冻土的强度及破坏应变都有较大影响,随着a角的增加,破坏时的广义剪应力qJ值先增加后减小,最小值出现在a=75°处,随着p值增加,qJ值先增加后减小;b值变化对强度的影响较小,而对破坏应变有较大影响;广义剪应力-广义剪应变曲线均为弹性塑性应变硬化曲线,且初始线性段的极限应变值在0.5%左右,不受应力路径变化的影响.分析应力与应变之间的关系,建立了定向剪切应力路径下冻结黏土的强度模型方程,进而求得广义剪切模量随应变发展的关系表达式,并发现初始广义剪切模量对冻结黏土应变的发展及破坏应变值有较大影响,且存在一临界值,对于冻结黏土,该临界值为6×105k Pa.a角、b值和p值的变化都会对冻结黏土的强度及变形产生较大影响.
To fully study the strength characteristics of frozen clay under complex stress paths such as the variation of principal stress axis direction,a series of different principle stress direction shear experiments were carried out using the frozen soil hollow cylinder apparatus at a temperature of-10 ℃ to investigate the influence of the major principal stress orientation angle a( defined in the vertical plane),the intermediate principal stress ratio b and the mean principal stress p on the strength characteristics of frozen clay. Analyzing the generalized shear stressgeneralized shear strain curves,the results showed that the strength of frozen clay was great influenced by the changes in a angle and p-value,and it was not affected by the changes in b-value. The failure strain was affected by the changes in these three parameters. The styles of stress-strain curves were all elastic-plastic strain harden curves and the range of elastic strain of the curves was about 0.5%,which was not affected by different stress paths. The strength model of frozen clay under different principle stress direction shear experiments was built through analyzing the relationship between stress and strain. Moreover,the relationship about generalized shear modulus EJtand strain was obtained,and the influence of initial shear modulus EJt 0 on EJt-strain curves was also discussed. The threshold value of EJt0 was found and was about 6×105 k Pa for frozen clay. The changes in a angle,b-value and p-value had great influence on the strength characteristics of frozen clay.
To fully study the strength characteristics of frozen clay under complex stress paths such as the variation of principal stress axis direction,a series of different principle stress direction shear experiments were carried out using the frozen soil hollow cylinder apparatus at a temperature of-10 ℃ to investigate the influence of the major principal stress orientation angle a( defined in the vertical plane),the intermediate principal stress ratio b and the mean principal stress p on the strength characteristics of frozen clay. Analyzing the generalized shear stressgeneralized shear strain curves,the results showed that the strength of frozen clay was great influenced by the changes in a angle and p-value,and it was not affected by the changes in b-value. The failure strain was affected by the changes in these three parameters. The styles of stress-strain curves were all elastic-plastic strain harden curves and the range of elastic strain of the curves was about 0.5%,which was not affected by different stress paths. The strength model of frozen clay under different principle stress direction shear experiments was built through analyzing the relationship between stress and strain. Moreover,the relationship about generalized shear modulus EJtand strain was obtained,and the influence of initial shear modulus EJt 0 on EJt-strain curves was also discussed. The threshold value of EJt0 was found and was about 6×105 k Pa for frozen clay. The changes in a angle,b-value and p-value had great influence on the strength characteristics of frozen clay.
引文
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[13]HIGHT D W,GENS A,SYMES M J.The development of a new hollow cylinder apparatus for investigating the effects of principal stress rotation in soils[J].Geotechnique,1983,33(4):355-383.DOI:10.1680/geot.1983.33.4.355.
[14]姚兆明,姜自华,王春萌,等.恒定主应力偏转角下黏土不排水剪切特性分析[J].力学与实践,2016,38(1):56-62.DOI:10.6052/1000-0879-15-104.YAO Zhaoming,JIANG Zihua,WANG Chunmeng,et al.Characteristics of clay subjected to undrained shear with consideration of influence of deflection angle of principal stress axis[J].Mechanics in Engineering,2016,38(1):56-62.DOI:10.6052/1000-0879-15-104.
[15]柳艳华,谢永利.主应力轴旋转下中主应力系数对软黏土性状的影响[J].交通运输工程学报,2015,15(3):27-33,61.DOI:10.3969/j.issn.1671-1637.2015.03.005.LIU Yanhua,XIE Yongli.Influence of intermediate principal stress coefficient on character of soft clay under rotation of principal stress axes[J].Journal of Traffic and Transportation Engineering,2015,15(3):27-33,61.DOI:10.3969/j.issn.1671-1637.2015.03.005.
[16]钱建固,杜子博.纯主应力轴旋转下饱和软黏土的循环弱化及非共轴性[J].岩土工程学报,2016,38(8):1381-1390.DOI:10.11779/CJGE201608004.QIAN Jiangu,DU Zibo.Cyclic degradation and non-coaxiality of saturated soft clay subjected to pure rotation of principal stress axis[J].Chinese Journal of Geotechnical Engineering,2016,38(8):1381-1390.DOI:10.11779/CJGE201608004.
[17]PRADEL D,ISHIHARA K,GUTIERREZ M.Yielding and flow of sand under principal stress axes rotation[J].Soils&Foundations,1990,30(1):87-99.DOI:10.3208/sandf1972.30.87.
[18]郭妍,王大雁,马巍,等.冻土空心圆柱仪的研发与应用[J].哈尔滨工业大学学报,2016,48(12):114-120.DOI:10.11918/j.issn.0367-6234.2016.12.016.GUO Yan,WANG Dayan,MA Wei,et al.Development and application of frozen hollow cylinder apparatus[J].Journal of Harbin Institute of Technology,2016,48(12):114-120.DOI:10.11918/j.issn.0367-6234.2016.12.016.
[19]沈瑞福,王洪瑾,周景星.动主应力轴连续旋转下砂土的动强度[J].水利学报,1996(1):27-33.DOI:10.13243/j.cnki.slxb.1996.01.005.SHEN Ruifu,WANG Hongjin,ZHOU Jingxing.Dynamic of sand under cyclic rotation of principal stress directions[J].Journal of Hydraulic Engineering,1996(1):27-33.DOI:10.13243/j.cnki.slxb.1996.01.005.
[20]李广信.高等土力学[M].北京:清华大学出版社,2005.LI Guangxin.Advanced soil mechanics[M].Beijing:Tsinghua University Press,2005.
[2]王大雁,马巍,常小晓,等.深部人工冻土抗变形特性研究[J].岩土工程学报,2005,27(4):418-421.DOI:10.3321/j.issn:1000-4548.2005.04.011.WANG Dayan,MA Wei,CHANG Xiaoxiao,et al.Study on resistance to deformation of artificially frozen soil in deep alluvium[J].Chinese Journal of Geotechnical Engineering,2005,27(4):418-421.DOI:10.3321/j.issn:1000-4548.2005.04.011.
[3]ALKIRE B D,ANDERSLAND O B.The effect of confining pressure on the mechanical properties of sand-ice materials[J].Journal of Glaciology,1973,12(66):469-481.DOI:10.1017/S0022143000031889.
[4]张锋,林波,冯德成,等.季节冻土区长期交通荷载下公路路基永久变形特性[J].哈尔滨工业大学学报,2017,49(3):120-126.DOI:10.11918/j.issn.0367-6234.2017.03.019.ZHANG Feng,LIN Bo,FENG Decheng,et al.Permanent deformation of subgrade induced by long-term truck traffic loading in seasonally frozen regions[J].Journal of Harbin Institute of Technology,2017,49(3):120-126.DOI:10.11918/j.issn.0367-6234.2017.03.019.
[5]MA Wei,WU Ziwang,ZHANG Lixin,et al.Analyses of process on the strength decrease in frozen soils under high confining pressures[J].Cold Regions Science and Technology,1999,29(1):1-7.DOI:10.1016/S0165-232X(98)00020-2.
[6]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):319-322.MA Wei,WU Ziwang,ZHANG Changqing.Strength and yield criterion of frozen soil[J].Journal of Glaciology and Geocryology,1993,15(1):319-322.
[7]吴紫汪,马巍.冻结砂土的强度特性[J].冰川冻土,1994,16(1):15-20.WU Ziwang,MA Wei.Strength characteristics of frozen sandy soil[J].Journal of Glaciology and Geocryology,1994,16(1):15-20.
[8]ZHU Yuanlin,ZHANG Jiayi.Constitutive relations of frozen soil in uniaxial compression[C]//Proceeding of 6th Internet Conference on Permafrost.Beijing:[s.n.],1991:1092-1095.
[9]陈湘生.人工冻土瞬时三轴剪切强度特征的试验研究[J].建井技术,1992(6):38-40.DOI:10.19458/j.cnki.cn11-2456/td.1992.06.017.CHEN Xiangsheng.Experimental study on strength of artificially frozen soil under transient triaxial compression[J].Mine Construction Technology,1992(6):38-40.DOI:10.19458/j.cnki.cn11-2456/td.1992.06.017.
[10]FISH A M.Strength of frozen soil under a combined stress state[C]//Proceedings of the 6thInternational Symposium on Ground Freezing.Beijing:[s.n.],1991:135-145.
[11]王大雁,马巍,常小晓.K0固结后卸载状态下冻土应力-应变特性研究[J].岩石力学与工程学报,2004,23(8):1252-1256.DOI:10.3321/j.issn:1000-6915.2004.08.004.WANG Dayan,MA Wei,CHANG Xiaoxiao.Study on behavior of stress-stain for frozen soils subjected to K0consolidation by unloading triaxial shear tests[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(8):1252-1256.DOI:10.3321/j.issn:1000-6915.2004.08.004.
[12]赖远明,程红彬,高志华,等.冻结砂土的应力-应变关系及非线性莫尔强度准则[J].岩石力学与工程学报,2007,26(8):1612-1617.DOI:10.3321/j.issn:1000-6915.2007.08.011.LAI Yuanming,CHENG Hongbin,GAO Zhihua,et al.Stress-strain relationships and nonlinear Mohr strength criterion of frozen sand clay[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(8):1612-1617.DOI:10.3321/j.issn:1000-6915.2007.08.011.
[13]HIGHT D W,GENS A,SYMES M J.The development of a new hollow cylinder apparatus for investigating the effects of principal stress rotation in soils[J].Geotechnique,1983,33(4):355-383.DOI:10.1680/geot.1983.33.4.355.
[14]姚兆明,姜自华,王春萌,等.恒定主应力偏转角下黏土不排水剪切特性分析[J].力学与实践,2016,38(1):56-62.DOI:10.6052/1000-0879-15-104.YAO Zhaoming,JIANG Zihua,WANG Chunmeng,et al.Characteristics of clay subjected to undrained shear with consideration of influence of deflection angle of principal stress axis[J].Mechanics in Engineering,2016,38(1):56-62.DOI:10.6052/1000-0879-15-104.
[15]柳艳华,谢永利.主应力轴旋转下中主应力系数对软黏土性状的影响[J].交通运输工程学报,2015,15(3):27-33,61.DOI:10.3969/j.issn.1671-1637.2015.03.005.LIU Yanhua,XIE Yongli.Influence of intermediate principal stress coefficient on character of soft clay under rotation of principal stress axes[J].Journal of Traffic and Transportation Engineering,2015,15(3):27-33,61.DOI:10.3969/j.issn.1671-1637.2015.03.005.
[16]钱建固,杜子博.纯主应力轴旋转下饱和软黏土的循环弱化及非共轴性[J].岩土工程学报,2016,38(8):1381-1390.DOI:10.11779/CJGE201608004.QIAN Jiangu,DU Zibo.Cyclic degradation and non-coaxiality of saturated soft clay subjected to pure rotation of principal stress axis[J].Chinese Journal of Geotechnical Engineering,2016,38(8):1381-1390.DOI:10.11779/CJGE201608004.
[17]PRADEL D,ISHIHARA K,GUTIERREZ M.Yielding and flow of sand under principal stress axes rotation[J].Soils&Foundations,1990,30(1):87-99.DOI:10.3208/sandf1972.30.87.
[18]郭妍,王大雁,马巍,等.冻土空心圆柱仪的研发与应用[J].哈尔滨工业大学学报,2016,48(12):114-120.DOI:10.11918/j.issn.0367-6234.2016.12.016.GUO Yan,WANG Dayan,MA Wei,et al.Development and application of frozen hollow cylinder apparatus[J].Journal of Harbin Institute of Technology,2016,48(12):114-120.DOI:10.11918/j.issn.0367-6234.2016.12.016.
[19]沈瑞福,王洪瑾,周景星.动主应力轴连续旋转下砂土的动强度[J].水利学报,1996(1):27-33.DOI:10.13243/j.cnki.slxb.1996.01.005.SHEN Ruifu,WANG Hongjin,ZHOU Jingxing.Dynamic of sand under cyclic rotation of principal stress directions[J].Journal of Hydraulic Engineering,1996(1):27-33.DOI:10.13243/j.cnki.slxb.1996.01.005.
[20]李广信.高等土力学[M].北京:清华大学出版社,2005.LI Guangxin.Advanced soil mechanics[M].Beijing:Tsinghua University Press,2005.