中国青藏铁路北麓河路基冻土动应变速率试验研究
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摘要
基于低温动三轴试验,研究中国青藏铁路北麓河路基冻结粉质黏土在轴向分级循环荷载作用下的变形特征。在不同负温、频率、围压、含水率条件下,考察冻土试件轴向残余应变时程曲线,获得轴向动应变速率受动应力幅值影响大,并随应力比增大而增大,随负温降低、频率升高、含水率增大而减小,随围压增加而线性增大的结论;据此,提出采用幂函数拟合应力比、负温、含水率、频率与轴向动应变速率之间关系,并合理解释冻土特有的振融沉陷的成因机理。有利于合理预测青藏铁路等实际工程在交通荷载作用下由冻土动力残余变形而产生的沉降量,并对于进一步研究冻土路基列车行驶振陷问题具有重要意义,且为建立冻土疲劳模型积累基础试验成果。
Based on dynamic tri-axial tests at low temperature,the deformation behavior of frozen silty clay from railway embankment of Qinghai-Tibet railway was studied under stepped axial cyclic loading.Time history curves of residual strain of frozen soil were investigated under different negative temperatures,frequencies,confining pressures and water contents.Conclusions were drawn as follows: the dynamic load greatly affected axial strain rate;the axial strain rate linearly increased with the increasing of stress ratio and confining pressure,while decreased with decreasing of temperature,increasing of frequency and water content.According to the test data,an exponential function was brought forward to fit the relation between stress ratio,negative temperature,water content,frequency and axial strain rate.Then,the mechanism of settlement for frozen soil,caused by vibration exciting defreeze was explained.The study was helpful for the settlement prediction of projects like Qinghai-Tibet railway induced by residual deformation of frozen soil under traffic load.It was important to further study the railway embankment settlement caused by train steering,and the experimental data for fatigue model of frozen soil were also provided.
Based on dynamic tri-axial tests at low temperature,the deformation behavior of frozen silty clay from railway embankment of Qinghai-Tibet railway was studied under stepped axial cyclic loading.Time history curves of residual strain of frozen soil were investigated under different negative temperatures,frequencies,confining pressures and water contents.Conclusions were drawn as follows: the dynamic load greatly affected axial strain rate;the axial strain rate linearly increased with the increasing of stress ratio and confining pressure,while decreased with decreasing of temperature,increasing of frequency and water content.According to the test data,an exponential function was brought forward to fit the relation between stress ratio,negative temperature,water content,frequency and axial strain rate.Then,the mechanism of settlement for frozen soil,caused by vibration exciting defreeze was explained.The study was helpful for the settlement prediction of projects like Qinghai-Tibet railway induced by residual deformation of frozen soil under traffic load.It was important to further study the railway embankment settlement caused by train steering,and the experimental data for fatigue model of frozen soil were also provided.
引文
[1]程国栋,杨成松.青藏铁路建设中的冻土力学问题[J].力学与实践,2006,28(3):1–8.(CHENG Guo-dong,YANG Cheng-song.Mechanics related with frozen ground in construction of Qinghai-Tibet Railway[J].Mechanics and Engineering,2006,28(3):1–8.(in Chinese))
[2]维亚洛夫C C.冻土流变学[M].刘建坤,刘尧军,徐艳,译.北京:中国铁道出版社,2005.(VYALOV S S.Rheologic theory of frozen soil[M].LIU Jian-qun,LIU Yao-jun,XU Yan,translators.Beijing:China Railway Publishing House,2005.(in Chinese))
[3]王丽霞,凌贤长.冻土路基地震破坏判别方法研究[J].岩石力学与工程学报,2005,24(4):638–642.(WANG Li-xia,LING Xian-zhang.Study on differentiate criteria of earthquake breakage of frozen roadbed[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(4):638–642.(in Chinese))
[4]FISH A M.Creep strength of Ottawa frozen sand under varying mean stress[C]//Proceedings of the 7th International Symposium on Ground Freezing,Nancy,France,1994:103–108.
[5]VAZIRI Hans,HAN Ying-cai.Ful-scale filed studies of the dynamic response of piles embedded in partially frozen soil[J].Canadian Geotechnical Journal,1991,28:708–718.
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[8]何平.饱和冻结粉土的动力特性[D].兰州:中国科学院兰州冰川冻土研究所,1992.(HE Ping.Dynamic behavior of saturated freezing silt[D].Lanzhou:State Key Laboratory of Frozen Soil Engineering,CAREERI,CAS,China,1992.(in Chinese))
[9]朱元林,何平,张家懿,等.冻土在振动荷载下的三轴蠕变模型[J].自然科学进展,1998,8(1):60–62.(ZHU Yuan-lin,HE Ping,ZHANG Jia-yi,et al.Triaxial creep model of frozen soil under vibratory load[J].Progress in Natural Science,1998,8(1):60–62.(in Chinese))
[10]尚守平,刘方成,杜运兴,等.应变累积对黏土动剪切模量和阻尼比影响的试验研究[J].岩土力学,2006,27(5):683–688.(SHANG Shou-ping,LIU Fang-cheng,DU Yun-xing,et al.Experimental study on effect of shear strain accumulation on dynamic shear modulus and damping ratio of clay soil[J].Rock and Soil Mechanics,2006,27(5):683–688.(in Chinese))
[11]徐春华,徐学燕,沈晓东.不等幅值循环荷载下冻土残余应变研究及其CT分析[J].岩土力学,2005,26(4):572–576.(XU Chun-hua,XU Xue-yan,SHEN Xiao-dong.Study on residual strain of frozen soil and CT analysis under cyclic loading of variable amplitudes[J].Rock and Soil Mechanics,2005,26(4):572–576.(in Chinese))
[12]赵淑萍,朱元林,何平,等.冻土动力学参数测试研究[J].岩石力学与工程学报,2003,22(增2):2677–2681.(ZHAO Shu-ping,ZHU Yuan-lin,He Ping,et al.Test study on dynamic mechanics parameters of frozen soil[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(S2):2677–2681.(in Chinese))
[2]维亚洛夫C C.冻土流变学[M].刘建坤,刘尧军,徐艳,译.北京:中国铁道出版社,2005.(VYALOV S S.Rheologic theory of frozen soil[M].LIU Jian-qun,LIU Yao-jun,XU Yan,translators.Beijing:China Railway Publishing House,2005.(in Chinese))
[3]王丽霞,凌贤长.冻土路基地震破坏判别方法研究[J].岩石力学与工程学报,2005,24(4):638–642.(WANG Li-xia,LING Xian-zhang.Study on differentiate criteria of earthquake breakage of frozen roadbed[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(4):638–642.(in Chinese))
[4]FISH A M.Creep strength of Ottawa frozen sand under varying mean stress[C]//Proceedings of the 7th International Symposium on Ground Freezing,Nancy,France,1994:103–108.
[5]VAZIRI Hans,HAN Ying-cai.Ful-scale filed studies of the dynamic response of piles embedded in partially frozen soil[J].Canadian Geotechnical Journal,1991,28:708–718.
[6]VYALOV S S.GMOSHINSKII S E,et al.The strength and creep of frozen soils and calculations for ice-soil retaining structures[R].US CRREL Translation,1963:76.
[7]LADANYI B.An engineering theory of creep of frozen soils[J].Canadian Geotechnical Journal,1972,9(1):63–88.
[8]何平.饱和冻结粉土的动力特性[D].兰州:中国科学院兰州冰川冻土研究所,1992.(HE Ping.Dynamic behavior of saturated freezing silt[D].Lanzhou:State Key Laboratory of Frozen Soil Engineering,CAREERI,CAS,China,1992.(in Chinese))
[9]朱元林,何平,张家懿,等.冻土在振动荷载下的三轴蠕变模型[J].自然科学进展,1998,8(1):60–62.(ZHU Yuan-lin,HE Ping,ZHANG Jia-yi,et al.Triaxial creep model of frozen soil under vibratory load[J].Progress in Natural Science,1998,8(1):60–62.(in Chinese))
[10]尚守平,刘方成,杜运兴,等.应变累积对黏土动剪切模量和阻尼比影响的试验研究[J].岩土力学,2006,27(5):683–688.(SHANG Shou-ping,LIU Fang-cheng,DU Yun-xing,et al.Experimental study on effect of shear strain accumulation on dynamic shear modulus and damping ratio of clay soil[J].Rock and Soil Mechanics,2006,27(5):683–688.(in Chinese))
[11]徐春华,徐学燕,沈晓东.不等幅值循环荷载下冻土残余应变研究及其CT分析[J].岩土力学,2005,26(4):572–576.(XU Chun-hua,XU Xue-yan,SHEN Xiao-dong.Study on residual strain of frozen soil and CT analysis under cyclic loading of variable amplitudes[J].Rock and Soil Mechanics,2005,26(4):572–576.(in Chinese))
[12]赵淑萍,朱元林,何平,等.冻土动力学参数测试研究[J].岩石力学与工程学报,2003,22(增2):2677–2681.(ZHAO Shu-ping,ZHU Yuan-lin,He Ping,et al.Test study on dynamic mechanics parameters of frozen soil[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(S2):2677–2681.(in Chinese))
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