循环荷载下饱和南京细砂的孔压增量模型
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摘要
等幅循环荷载的不排水三轴试验的结果表明,饱和南京细砂孔压比曲线的形状随循环周数比增大而发生规律性的变化。引入孔压增量比的概念,并定义有效动剪应力比和有效应力对数衰减率,发现孔压增量比的发展过程可分为下降段、平稳段和上升段;在平稳段和上升段,孔压增量比的累积量与有效动剪应力比的自然对数具有很好的线性关系,并推导出第N周的孔压增量比与第N-1周的有效应力比对数衰减率成正比,而与动应力幅值无关。据此建立的饱和南京细砂孔压增量模型,能够较好地描述等幅循环荷载作用引起的孔压比随循环周数的增大而增长的发展趋势。
Undrained triaxial tests are carried out for saturated Nanjing fine sand subjected to uniform cyclic loading.The curve shapes of the excess pore water pressure(EPWP) ratio regularly change with the increase of the ratio of number of cycles.The concept of EPWP increment ratio is introduced.Two new concepts of the effective dynamic shear stress ratio and the log decrement of effective stress are defined.It is found that the development of the EPWP increment ratio can be divided into three stages: descending stage,stable stage and ascending stage.At the stable and ascending stages,a satisfactory linear relationship is obtained between the accumulative EPWP increment ratio and the natural logarithm of the effective dynamic shear stress ratio.Accordingly it is deduced that the EPWP increment ratio at the number of cycle N is in direct proportion to the log decrement of the effective stress at the number of cycle N-1,but is independent of the cyclic stress amplitude.Based on the above analysis,a new EPWP increment model is developed,and it fits the test results for better prediction of the curves of EPWP generation.
Undrained triaxial tests are carried out for saturated Nanjing fine sand subjected to uniform cyclic loading.The curve shapes of the excess pore water pressure(EPWP) ratio regularly change with the increase of the ratio of number of cycles.The concept of EPWP increment ratio is introduced.Two new concepts of the effective dynamic shear stress ratio and the log decrement of effective stress are defined.It is found that the development of the EPWP increment ratio can be divided into three stages: descending stage,stable stage and ascending stage.At the stable and ascending stages,a satisfactory linear relationship is obtained between the accumulative EPWP increment ratio and the natural logarithm of the effective dynamic shear stress ratio.Accordingly it is deduced that the EPWP increment ratio at the number of cycle N is in direct proportion to the log decrement of the effective stress at the number of cycle N-1,but is independent of the cyclic stress amplitude.Based on the above analysis,a new EPWP increment model is developed,and it fits the test results for better prediction of the curves of EPWP generation.
引文
[1]SEED H B,MARTIN P P,LYSMER J.Pore-water pressure changes during soil liquefaction[J].American Society of Civil Engineers,Journal of the Geotechnical Engineering Division.1976,102(4):323-346.
[2]张建民,谢定义.饱和砂土振动孔隙水压力增长的实用算法[J].水利学报,1991(8):45-51.(ZHANG Jian-min,XIE Ding-yi.A practical method for calculation of seismic excess pore water pressure in saturated sand[J].Journal of Hydraulic Engineering,1991(8):45-51.(in Chinese))
[3]袁晓铭,孙锐,孟上九.土体地震大变形分析中Seed有效循环次数方法的局限性[J].岩土工程学报,2004(2):207-211.(YUAN Xiao-ming,SUN Rui,MENG Shang-jiu.Limitation of the seed's method of significant cyclic number in analyzing large deformation of soils during earthquake[J].Chinese Journal of Geotechnical Engineering,2004(2):207-211.(in Chinese))
[4]FINN W D L,BHATIA S K.Predictions of seismic pore water pressure[C].Stockholm,1982.
[5]郑颖人,徐干成,谢定义.一个新的内时参量动孔压模型及其适用性研究[J].水利学报,1995(12):39-53.(ZHENG Ying-ren,XU Gan-cheng,XIE Ding-yi.A pore-water pressure model with a new endochronic parameter and it's applicability[J].Journal of Hydraulic Engineering,1995(12):39-53.(in Chinese))
[6]IVSIC T.A model for presentation of seismic pore water pressures[J].Soil Dynamics and Earthquake Engineering,2006,26(2-4):191-199.
[7]TOWHATA I,ISHIHARA K.Shear work and pore water pressure in undrained shear[J].Soils and Foundations,1985,25(3):73-84.
[8]POLITO C P,GREEN R A,LEE J.Pore pressure generation models for sands and silty soils subjected to cyclic loading[J].Journal of Geotechnical and Geoenvironmental Engineering,2008,134(10):1490-1500.
[9]丰万玲,石兆吉.判别水平土层液化势的孔隙水压力分析方法[J].工程抗震与加固改造,1988(4):30-33.(FENG Wan-ling,SHI Zhao-ji.An analytical method using pore-water pressure for evaluation of liquefaction potential in level soil layer[J].Earthquake Resistant Engineering and Retrofitting,1988(4):30-33.(in Chinese))
[10]孙锐,袁晓铭.非均等固结下饱和砂土孔压增量简化计算公式[J].岩土工程学报,2005,27(9):1021-1025.(SUN Rui,YUAN Xiao-ming.Simplified incremental formula for estimating pore water pressure of saturated sands under anisotropic consolidation[J].Chinese Journal of Geotechnical Engineering,2005,27(9):1021-1025.(in Chinese))
[11]孙锐,袁晓铭.地震荷载下饱和砂土孔压增长时程计算方法[J].地震工程与工程振动,2006(3):261-263.(SUN Rui,YUAN Xiao-ming.A method for calculating time-dependent pore water pressure rise of saturated sands under earthquake loading[J].Earthquake Engineering and Engineering Vibration,2006(3):261-263.(in Chinese))
[12]ISHIBASHI I,SHERIF M A,TSUCHIYA C.Pore-pressure rise mechanism and soil liquefaction[J].Soils and Foundation,1977,17(2):17-27.
[13]ISHIBASHI I,SHERIF M A,CHENG Wenlon.The effects of soil parameters on pore-pressure-rise and liquefaction prediction[J].Soils and Foundations,1982,22(1):39-48.
[14]SHERIF M A,ISHIBASHI I,TSUCHIYA C.Pore-pressure prediction during earthquake loadings[J].Soils and Foundations.1978,18(4):19-30.
[15]陈国兴,朱定华,何启智.DSZ-1型动三轴试验机研制与性能试验[J].地震工程与工程振动.2002,22(6):71-74.(CHEN Guo-xing,ZHU Ding-hua,HE Qi-zhi.Development and test of DSZ-1 cyclic triaxial testing system[J].Earthquake Engineering and Engineering Vibaration.2002,22(6):71-74.(in Chinese))
[16]张克绪,谢君斐.土动力学[M].北京:地震出版社,1989.(ZHANG Ke-xu,XIE Jun-fei.Soil dynamics[M].Beijing:Seismological Press,1989.(in Chinese))
[2]张建民,谢定义.饱和砂土振动孔隙水压力增长的实用算法[J].水利学报,1991(8):45-51.(ZHANG Jian-min,XIE Ding-yi.A practical method for calculation of seismic excess pore water pressure in saturated sand[J].Journal of Hydraulic Engineering,1991(8):45-51.(in Chinese))
[3]袁晓铭,孙锐,孟上九.土体地震大变形分析中Seed有效循环次数方法的局限性[J].岩土工程学报,2004(2):207-211.(YUAN Xiao-ming,SUN Rui,MENG Shang-jiu.Limitation of the seed's method of significant cyclic number in analyzing large deformation of soils during earthquake[J].Chinese Journal of Geotechnical Engineering,2004(2):207-211.(in Chinese))
[4]FINN W D L,BHATIA S K.Predictions of seismic pore water pressure[C].Stockholm,1982.
[5]郑颖人,徐干成,谢定义.一个新的内时参量动孔压模型及其适用性研究[J].水利学报,1995(12):39-53.(ZHENG Ying-ren,XU Gan-cheng,XIE Ding-yi.A pore-water pressure model with a new endochronic parameter and it's applicability[J].Journal of Hydraulic Engineering,1995(12):39-53.(in Chinese))
[6]IVSIC T.A model for presentation of seismic pore water pressures[J].Soil Dynamics and Earthquake Engineering,2006,26(2-4):191-199.
[7]TOWHATA I,ISHIHARA K.Shear work and pore water pressure in undrained shear[J].Soils and Foundations,1985,25(3):73-84.
[8]POLITO C P,GREEN R A,LEE J.Pore pressure generation models for sands and silty soils subjected to cyclic loading[J].Journal of Geotechnical and Geoenvironmental Engineering,2008,134(10):1490-1500.
[9]丰万玲,石兆吉.判别水平土层液化势的孔隙水压力分析方法[J].工程抗震与加固改造,1988(4):30-33.(FENG Wan-ling,SHI Zhao-ji.An analytical method using pore-water pressure for evaluation of liquefaction potential in level soil layer[J].Earthquake Resistant Engineering and Retrofitting,1988(4):30-33.(in Chinese))
[10]孙锐,袁晓铭.非均等固结下饱和砂土孔压增量简化计算公式[J].岩土工程学报,2005,27(9):1021-1025.(SUN Rui,YUAN Xiao-ming.Simplified incremental formula for estimating pore water pressure of saturated sands under anisotropic consolidation[J].Chinese Journal of Geotechnical Engineering,2005,27(9):1021-1025.(in Chinese))
[11]孙锐,袁晓铭.地震荷载下饱和砂土孔压增长时程计算方法[J].地震工程与工程振动,2006(3):261-263.(SUN Rui,YUAN Xiao-ming.A method for calculating time-dependent pore water pressure rise of saturated sands under earthquake loading[J].Earthquake Engineering and Engineering Vibration,2006(3):261-263.(in Chinese))
[12]ISHIBASHI I,SHERIF M A,TSUCHIYA C.Pore-pressure rise mechanism and soil liquefaction[J].Soils and Foundation,1977,17(2):17-27.
[13]ISHIBASHI I,SHERIF M A,CHENG Wenlon.The effects of soil parameters on pore-pressure-rise and liquefaction prediction[J].Soils and Foundations,1982,22(1):39-48.
[14]SHERIF M A,ISHIBASHI I,TSUCHIYA C.Pore-pressure prediction during earthquake loadings[J].Soils and Foundations.1978,18(4):19-30.
[15]陈国兴,朱定华,何启智.DSZ-1型动三轴试验机研制与性能试验[J].地震工程与工程振动.2002,22(6):71-74.(CHEN Guo-xing,ZHU Ding-hua,HE Qi-zhi.Development and test of DSZ-1 cyclic triaxial testing system[J].Earthquake Engineering and Engineering Vibaration.2002,22(6):71-74.(in Chinese))
[16]张克绪,谢君斐.土动力学[M].北京:地震出版社,1989.(ZHANG Ke-xu,XIE Jun-fei.Soil dynamics[M].Beijing:Seismological Press,1989.(in Chinese))
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