土体地震大变形分析中Seed有效循环次数方法的局限性
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摘要
采用地震波输入动三轴实验并结合实际震害现象,研究常用的Seed有效循环次数方法在分析地震下土体大变形和地基差降中的合理性和局限性。结果表明有效循环次数方法的主要局限有:不适于大脉冲强地震动下土体残余变形的分析,不能反映地震动本身不规则性和不对称性、土的各向异性特性以及土层横向分布不均匀带来的土体永久变形和地基震陷的差异,不适应土体变形时程分析的要求,用于软弱地基上建筑物不均匀震陷的计算容易导致不合理的结果。
The reasonableness and limitation of the Seed's method of the significant cyclic number for analyzing the large deformation of soils and differential settlements of subsoil during earthquakes are discussed on the basis of dynamic biaxial tests and the post - earthquake investigation. The results indicate that the significant cyclic number method is not suitable for analyzing the residual strain of soils under the seismic loads with the large pulse. Also, the effects of the asymmetry and irregularity of seismic ground motion, the anisotropic property of soil and transverse non-uniform distribution of soil layer on the permanent deformation of soils and earthquake-induced differential settlements of subsoil can not be considered by this method. Some unreasonable results will be obtained when this method is used to calculate the time history of the deformation of soils under earthquake loading and the earthquake-induced differential settlements of buildings.
The reasonableness and limitation of the Seed's method of the significant cyclic number for analyzing the large deformation of soils and differential settlements of subsoil during earthquakes are discussed on the basis of dynamic biaxial tests and the post - earthquake investigation. The results indicate that the significant cyclic number method is not suitable for analyzing the residual strain of soils under the seismic loads with the large pulse. Also, the effects of the asymmetry and irregularity of seismic ground motion, the anisotropic property of soil and transverse non-uniform distribution of soil layer on the permanent deformation of soils and earthquake-induced differential settlements of subsoil can not be considered by this method. Some unreasonable results will be obtained when this method is used to calculate the time history of the deformation of soils under earthquake loading and the earthquake-induced differential settlements of buildings.
引文
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[2] Ishihara K, Yasuda S. Sand liquefaction under random earthquake loading condition[A].5th WCEE[C]. 1973． 329-328．
[3] Nagase H,Ishihara K. Effects of Load Irregularity on the Cyclic Behavior of Sand Dynamics and Earthquake Engineering[J]. Soil Dynamics and Earthquake Engineering, 1987, 6(4) :239-248．
[4] 沈智刚,Harder L F,等.随机荷载下砂土的动力反应[J].国外地震工程,1981,(1) :52-58．
[5] 谢定义.土动力学[M].西安:西安交通大学出版社,1988． 84-85．
[6] 刘惠珊.液化震陷予估的经验公式(初探)[A].第四届全国土动力学学术会议论文集[C].1994． 298-292．
[7] Takada S,Tanabe K. Estimation of earthquake induced settlement for lifeline engineering[A] .9th WCEE[C]. 1988． 109-114．
[8] 杨石红,刘静蓉,刘金珠,等.软弱地基土层震陷简化计算方法研究[J].世界地震工程,1997,(6) :53-61．
[9] 石兆吉,郁寿松,翁鹿年.塘沽新港地区震陷计算分析[J].土木工程学报,1988,(4) :24-33．
[10] 孙 锐,袁晓铭,韩俊伟,等.全自动地震波输入动三轴装置指标和功能测试[J].地震工程与工程振动,2002,(3) :100-105．
[11] 郁寿松,石兆吉.土壤震陷试验研究[J].岩土工程学报,1989,11(4) :35-44．
[12] 孟上九,袁晓铭,孙 锐.建筑物不均匀震陷机理的振动台实验研究[J].岩土工程学报,2002,24(6) :747-751．
[2] Ishihara K, Yasuda S. Sand liquefaction under random earthquake loading condition[A].5th WCEE[C]. 1973． 329-328．
[3] Nagase H,Ishihara K. Effects of Load Irregularity on the Cyclic Behavior of Sand Dynamics and Earthquake Engineering[J]. Soil Dynamics and Earthquake Engineering, 1987, 6(4) :239-248．
[4] 沈智刚,Harder L F,等.随机荷载下砂土的动力反应[J].国外地震工程,1981,(1) :52-58．
[5] 谢定义.土动力学[M].西安:西安交通大学出版社,1988． 84-85．
[6] 刘惠珊.液化震陷予估的经验公式(初探)[A].第四届全国土动力学学术会议论文集[C].1994． 298-292．
[7] Takada S,Tanabe K. Estimation of earthquake induced settlement for lifeline engineering[A] .9th WCEE[C]. 1988． 109-114．
[8] 杨石红,刘静蓉,刘金珠,等.软弱地基土层震陷简化计算方法研究[J].世界地震工程,1997,(6) :53-61．
[9] 石兆吉,郁寿松,翁鹿年.塘沽新港地区震陷计算分析[J].土木工程学报,1988,(4) :24-33．
[10] 孙 锐,袁晓铭,韩俊伟,等.全自动地震波输入动三轴装置指标和功能测试[J].地震工程与工程振动,2002,(3) :100-105．
[11] 郁寿松,石兆吉.土壤震陷试验研究[J].岩土工程学报,1989,11(4) :35-44．
[12] 孟上九,袁晓铭,孙 锐.建筑物不均匀震陷机理的振动台实验研究[J].岩土工程学报,2002,24(6) :747-751．
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