主应力轴循环旋转下原状软黏土临界性状研究
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摘要
针对在交通、波浪等动荷载下土体所受应力状态具有主应力轴循环旋转的特征,对杭州地区典型原状软黏土开展不排水模拟试验.主应力轴双幅循环旋转的试验结果表明,试样扭剪、轴向应变发展受主应力轴旋转角度的影响,当转角大于一定值时,破坏应变以扭剪应变占主导,反之则要考虑扭剪和轴向等应变的共同影响.在同一旋转频率下,随着剪应力提高,试样破坏应变同步提高,且与破坏振次对数值成线性关系;若剪应力幅值不变,随旋转频率提高,临界破坏应变同步减少,破坏振次大幅提升,两者在对数曲线上亦可用线性关系表示.与等剪应力幅值的主应力轴双幅循环旋转试验结果相比,当单幅循环旋转破坏时扭剪应变很大,且受频率或剪应力幅值影响小,同时最小破坏剪应力也有显著提高.
A series of undrained tests on typical Hangzhou intact soft clay were conducted to investigate the influence of cyclic principal stress rotation induced by traffic or wave loads on soil's properties.Test results of two-amplitude cyclic principal stress rotation show that the induced torsional shear strain and axial strain are greatly influenced by the angle of principal stress rotation.If the angle is larger than a certain value,the torsional shear strain is dominating;if smaller than that value,the torsional shear strain and axial strain are at the same magnitude and should be considered together.At the same frequency,the critical failure strain increases with the shear stress level,and has a linear relationship with the logarithmic cycles.At the same shear stress level,the critical strain decreases with increasing frequency,while the critical rotation cycles increase greatly.The logarithmic strain and logarithmic cycles have linear relationship.Compared with the results of two-amplitude cyclic principal stress rotation tests at the same shear stress level,the critical torsional shear strain in one-amplitude cyclic rotation tests is much larger and influenced neither by frequency nor shear stress level,moreover the minimum failure shear stress level.
A series of undrained tests on typical Hangzhou intact soft clay were conducted to investigate the influence of cyclic principal stress rotation induced by traffic or wave loads on soil's properties.Test results of two-amplitude cyclic principal stress rotation show that the induced torsional shear strain and axial strain are greatly influenced by the angle of principal stress rotation.If the angle is larger than a certain value,the torsional shear strain is dominating;if smaller than that value,the torsional shear strain and axial strain are at the same magnitude and should be considered together.At the same frequency,the critical failure strain increases with the shear stress level,and has a linear relationship with the logarithmic cycles.At the same shear stress level,the critical strain decreases with increasing frequency,while the critical rotation cycles increase greatly.The logarithmic strain and logarithmic cycles have linear relationship.Compared with the results of two-amplitude cyclic principal stress rotation tests at the same shear stress level,the critical torsional shear strain in one-amplitude cyclic rotation tests is much larger and influenced neither by frequency nor shear stress level,moreover the minimum failure shear stress level.
引文
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[9]GRA¨BE P J.Resilient and permanent deformation ofrailway foundations under principal stress rotation[D].Southampton:University of Southampton,2002.
[10]郭莹,栾茂田,许成顺,等.主应力方向变化对松砂不排水动强度特性影响[J].岩土工程学报,2003,25(6):666-670.GUO Ying,LUAN Mao-tian,XU Cheng-shun,et al.Effect of variation of principal stress orientation on un-drained dynamic strength behavior of loose sand[J].Chinese Journal of Geotechnical Engineering,2003,25(6):666-670.
[11]SHIBUYA S,HIGHT D W.Predictions of pore pres-sure under undrained cyclic principal stress rotation[C]∥Proceedings of the 12th International Conference onSoil Mechanics and Foundation Engineering.Rio de Ja-neiro:[s.n.],1989:123-126.
[12]沈扬,周建,龚晓南.空心圆柱仪(HCA)模拟恒定围压下主应力轴循环旋转应力路径能力分析[J].岩土工程学报,2006,28(3):281-287.SHEN Yang,ZHOU Jian,GONG Xiao-nan.Analysis onthe ability of HCA to imitate cyclic principal stress rotationunder constant confining pressure[J].Chinese Journal ofGeotechnical Engineering,2006,28(3):281-287.
[13]沈扬,周建,张金良,等.考虑主应力方向变化的原状黏土强度及超静孔压特性研究[J].岩土工程学报,2007,29(6):843-847.SHEN Yang,ZHOU Jian,ZHANG Jin-liang,et al.Research on characteristics of intact clay’s strength andpore pressure considering variable principal stress di-rection[J].Chinese Journal of Geotechnical Engineer-ing,2007,29(6):843-847.
[14]ANDERSEN K H,KLEVEN A,HEIEN D.Cyclic soildata for design of gravity structure[J].Journal ofGeotechnical Engineering,1988,114(5):517-539.
[2]TOWHATA I,ISHIHARA K.Undrained strength ofsand undergoing cyclic rotation of principal stress axes[J].Soils and Foundations,1985,25(2):135-147.
[3]刘元雪,郑颖人.含主应力轴旋转的土体本构关系研究进展[J].力学进展,2000,30(4):597-604.LIU Yuan-xue,ZHENG Ying-ren.Research develop-ment of soils constitutive relation involving principalstress axes rotation[J].Advances in Mechanics,2000,30(4):597-604.
[4]付磊,王洪瑾,周景星.主应力偏转角对砂砾料动力特性影响的试验研究[J].岩土工程学报,2000,22(4):435-440.FU Lei,WANG Hong-jin,ZHOU Jing-xing.Effect ofthe initial rotation angle of principal stress on the dynam-ic properties of soil[J].Chinese Journal of GeotechnicalEngineering,2000,22(4):435-440.
[5]郭莹,栾茂田,何杨,等.复杂应力条件下饱和松砂孔隙水压力增长特性的试验研究[J].地震工程与工程振动,2004,24(3):139-144.GUO Ying,LUAN Mao-tian,HE Yang,et al.Experi-mental study on development pattern of shaking-inducedpore water pressure of saturated loose sand under com-plex loading[J].Earthquake Engineering and Engineer-ing Vibration,2004,24(3):139-144.
[6]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,1996,27(1):27-33.SHEN Rui-fu,WANG Hong-jin,ZHOU Jing-xing.Dy-namic strength of sand under cyclic rotation of principalstress directions[J].Journal of Hydraulic Engineering,1996,27(1):27-33.
[7]ARTHUR J R F,CHUA K S,DUNSTAN T,et al.Princi-pal stress rotation:a missing parameter[J].Journal of theGeotechnical Engineering Division,Proceedings of the Ameri-can Society of Civil Engineers,1980,106(4):419-433.
[8]WONG R K S,ARTHUR J R F.Sand sheared by stres-ses with cyclic variations in direction[J].Geotechnique,1986,36(2):215-226.
[9]GRA¨BE P J.Resilient and permanent deformation ofrailway foundations under principal stress rotation[D].Southampton:University of Southampton,2002.
[10]郭莹,栾茂田,许成顺,等.主应力方向变化对松砂不排水动强度特性影响[J].岩土工程学报,2003,25(6):666-670.GUO Ying,LUAN Mao-tian,XU Cheng-shun,et al.Effect of variation of principal stress orientation on un-drained dynamic strength behavior of loose sand[J].Chinese Journal of Geotechnical Engineering,2003,25(6):666-670.
[11]SHIBUYA S,HIGHT D W.Predictions of pore pres-sure under undrained cyclic principal stress rotation[C]∥Proceedings of the 12th International Conference onSoil Mechanics and Foundation Engineering.Rio de Ja-neiro:[s.n.],1989:123-126.
[12]沈扬,周建,龚晓南.空心圆柱仪(HCA)模拟恒定围压下主应力轴循环旋转应力路径能力分析[J].岩土工程学报,2006,28(3):281-287.SHEN Yang,ZHOU Jian,GONG Xiao-nan.Analysis onthe ability of HCA to imitate cyclic principal stress rotationunder constant confining pressure[J].Chinese Journal ofGeotechnical Engineering,2006,28(3):281-287.
[13]沈扬,周建,张金良,等.考虑主应力方向变化的原状黏土强度及超静孔压特性研究[J].岩土工程学报,2007,29(6):843-847.SHEN Yang,ZHOU Jian,ZHANG Jin-liang,et al.Research on characteristics of intact clay’s strength andpore pressure considering variable principal stress di-rection[J].Chinese Journal of Geotechnical Engineer-ing,2007,29(6):843-847.
[14]ANDERSEN K H,KLEVEN A,HEIEN D.Cyclic soildata for design of gravity structure[J].Journal ofGeotechnical Engineering,1988,114(5):517-539.
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