黄河三角洲粉土液化的试验研究
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摘要
在野外自然地理和地质调查的基础上,以黄河地区可液化场地粉土为研究对象,利用室内动三轴和振动柱试验进行测定,分析了动荷载作用下粉土的动应力应变关系并模拟了地震荷载作用下粉土的孔压响应及抗液化强度,得出了液化破坏标准,提出了原状粉土的振动孔压上升模型。对试验结果进行分析发现,随着粘粒含量的增加,粉砂、粉土、粉质粘土、粘土达到相同剪应变所需的动剪应力也依次增加;粉土孔压比0.68、粉砂土孔压比0.87作为液化破坏开始的标志;粉土发生液化所需的循环应力比大于砂土。这些研究为以后建立适合本地区的饱和地基土地震破坏判别方法提供了参数和依据。
The silt of Huanghe is chosen as research object in this paper on the basis of physical geography and geological survey.The stress-strain relationship of the silt under dynamic loading is established by using the results of dynamic triaxial and resonance vibration tests.Meantime pore pressure response and liquefaction strength of the silt under the simulated earthquake action are analyzed.Then the standardization of failure and the model of pore pressure for the undisturbed silt are proposed.Through the analysis of the tested results,the following conclusions are drawn.First,the dynamic stress of the same strain for the silty sand,silt,silty clay,and clay are larger with the increasing clay content.Second,pore water pressure ratio for the silt is 0.68,and is 0.87 for the silty sand when liquefaction failure is occurred.Third,as to silty sand,the cyclic stress ratio must be increased if silt liquefaction is occurred.The tested results can provide the parameters and basis for the evaluating method of the silt failure under earthquakes,which suit to the saturated foundation land of the native area.
The silt of Huanghe is chosen as research object in this paper on the basis of physical geography and geological survey.The stress-strain relationship of the silt under dynamic loading is established by using the results of dynamic triaxial and resonance vibration tests.Meantime pore pressure response and liquefaction strength of the silt under the simulated earthquake action are analyzed.Then the standardization of failure and the model of pore pressure for the undisturbed silt are proposed.Through the analysis of the tested results,the following conclusions are drawn.First,the dynamic stress of the same strain for the silty sand,silt,silty clay,and clay are larger with the increasing clay content.Second,pore water pressure ratio for the silt is 0.68,and is 0.87 for the silty sand when liquefaction failure is occurred.Third,as to silty sand,the cyclic stress ratio must be increased if silt liquefaction is occurred.The tested results can provide the parameters and basis for the evaluating method of the silt failure under earthquakes,which suit to the saturated foundation land of the native area.
引文
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[2]曹宇春,王天龙.上海粉土液化特性及孔压模型的试验研究[J].上海地质,1998,(3):60-64.
[3]王建华,要明伦.循环应变下饱和砂(粉)土衰化动力特性研究[J].水利学报,1997,(7):24-30.
[4]景立平,崔杰,李立云,郑志华.徐州市棠张镇饱和粉土液化性能试验研究[J].地震工程与工程振动,2004,24(5):160-164.
[5]Hardin B.O.Dmevich V P.Shear modulus and damping in soil:design equation and curves[J].Journal of Soil Mechanics and Foundation Divi-sion ASCE,1972,98(SM7):667-692.
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