土体液化动力分析数值模型
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摘要
基于有效应力原理,采用满足Masing准则的修正双曲线模型描述土的本构关系,建立了一种土体液化动力分析的数值模型,该模型反映出地震引起孔压增长及伴随的土体软化效应且特别考虑了围压对场地液化的影响.孔压增长模型选用Ishibashi和Sherif等提出的等效循环孔压模式.为了验证模型在模拟地震触发场地液化分析的可靠性,直接针对自由液化场地振动台试验,建立了自由液化场地地震反应的二维分析模型和计算方法;土箱-地基边界采用并联弹簧-阻尼器模拟,体系的动力方程采用Wilson-θ逐步积分法求解.通过试验值与计算值的对比分析,评估了数值建模途径和计算方法的可靠性;总体来看,试验结果与计算结果吻合较好,一定程度上验证了模型良好的模拟能力和正确性,可有效地用于场地液化动力分析.
This paper presents an effective stress-based numerical model for dynamic analysis of soil liquefaction considering the effect of confining pressure on of dynamic properties soil,which can be used to describe the pore pressure increment and the consequent loss of soil strength due to earthquake-induced shaking.The emendatory hyperbolic model which meets Masing rule is adopted for nonlinear analysis of soils in numerical model.The pore pressure generation is calculated using the equivalent cycle pore pressure model developed by Ishibashi and Sherif et al.To demonstrate the relability of the new method for dynamic soil liquefaction analysis,a two-dimensional numerical model is directly established to simulate shaking table test for seismic response of liquefiable ground,the parallel spring-damper connection is used to simulate the artificial boundary of computational domain and the Wilson-θ integral method is selected to solve dynamic equations of seismic response.The results obtained from the new analysis agree well with recorded accelerations and pore pressure ratio in the shaking table test,which shows the reliability and validity of the numerical model.
This paper presents an effective stress-based numerical model for dynamic analysis of soil liquefaction considering the effect of confining pressure on of dynamic properties soil,which can be used to describe the pore pressure increment and the consequent loss of soil strength due to earthquake-induced shaking.The emendatory hyperbolic model which meets Masing rule is adopted for nonlinear analysis of soils in numerical model.The pore pressure generation is calculated using the equivalent cycle pore pressure model developed by Ishibashi and Sherif et al.To demonstrate the relability of the new method for dynamic soil liquefaction analysis,a two-dimensional numerical model is directly established to simulate shaking table test for seismic response of liquefiable ground,the parallel spring-damper connection is used to simulate the artificial boundary of computational domain and the Wilson-θ integral method is selected to solve dynamic equations of seismic response.The results obtained from the new analysis agree well with recorded accelerations and pore pressure ratio in the shaking table test,which shows the reliability and validity of the numerical model.
引文
[1]DAVIS R O,BERRILL J B.Energy dissipation and seismic liquefaction in sands[J].Earthquake Engi-neering and Structural Dynamics,1982,10(1):117-129.
[2]TOKIDA K.Simplified procedure to estimate flow by soil liquefaction[J].Soil Dynamics and Earthquake Engineering,1993(6):381-396.
[3]PYKE R.Nonlinear soil models for irregular cyclic loadings[J].ASCE,Journal of Geotechnical Engi-neering Division,1979,105(6):715-726.
[4]VUCETIC M,DOBRY R.Effect of Soil Plasticity on cyclic respones[J].Journal of Geotechnical Engineer-ing,ASCE,1991(1):89-107.
[5]HARDIN B,IWASAKI T,Tatsuoka,F.,Takagi Y.Shear moduli of sands under cyclic torisional shear loading[J].Soil and Foundations,1978,18(1):39-56.
[6]HARDIN B,DRNEVISH O.Shear modulus and damp-ing in soils:design equation and curve[J].Journal of the Soil Mechanics and Foundations Division,ASCE,1972,98(7):667-692.
[7]ISHIBASHI I,ZHANG X.Unified dynamic shear moduli and damping ratios of sand and clay[J].Soils and Foundations,1993,33(1):182-191.
[8]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):67-73.
[9]石兆吉,王兰民.土壤动力特性——液化势及危害性评价[M].北京:地震出版社,1999.
[10]伍小平,孙利民,胡世德,等.振动台试验用层状剪切变形土箱的研制[J].同济大学学报,2002,30(7):781-785.
[11]凌贤长,王臣,王志强,等.自由场地液化大型振动台模型试验研究[J].地震工程与工程振动,2003,23(6):138-143.
[2]TOKIDA K.Simplified procedure to estimate flow by soil liquefaction[J].Soil Dynamics and Earthquake Engineering,1993(6):381-396.
[3]PYKE R.Nonlinear soil models for irregular cyclic loadings[J].ASCE,Journal of Geotechnical Engi-neering Division,1979,105(6):715-726.
[4]VUCETIC M,DOBRY R.Effect of Soil Plasticity on cyclic respones[J].Journal of Geotechnical Engineer-ing,ASCE,1991(1):89-107.
[5]HARDIN B,IWASAKI T,Tatsuoka,F.,Takagi Y.Shear moduli of sands under cyclic torisional shear loading[J].Soil and Foundations,1978,18(1):39-56.
[6]HARDIN B,DRNEVISH O.Shear modulus and damp-ing in soils:design equation and curve[J].Journal of the Soil Mechanics and Foundations Division,ASCE,1972,98(7):667-692.
[7]ISHIBASHI I,ZHANG X.Unified dynamic shear moduli and damping ratios of sand and clay[J].Soils and Foundations,1993,33(1):182-191.
[8]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):67-73.
[9]石兆吉,王兰民.土壤动力特性——液化势及危害性评价[M].北京:地震出版社,1999.
[10]伍小平,孙利民,胡世德,等.振动台试验用层状剪切变形土箱的研制[J].同济大学学报,2002,30(7):781-785.
[11]凌贤长,王臣,王志强,等.自由场地液化大型振动台模型试验研究[J].地震工程与工程振动,2003,23(6):138-143.
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