饱和黄土孔压增长模式与液化机理试验研究
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摘要
通过室内饱和原状黄土液化试验研究,探讨了孔压增长规律,并从微观结构角度研究了黄土液化机理。研究结果表明:未湿陷饱和黄土结构是一种介稳结构,在地震作用下,介稳结构遭到破坏,塌陷和剪缩共同作用造成黄土较大的收缩体积应变并引起孔隙水压力迅速上升。提出的修正A型曲线方程可以用来拟合孔压曲线,拟合参数β隐含了动应力的大小对孔压增长的贡献,而体应变υ则反映了湿陷分量对孔压的影响,两者不同组合决定曲线形态丰满程度。液化机理较为合理地解释了塔吉克和海原黄土在近乎平坦的缓坡上形成的泥流。
The increasing rhythm of pore water pressure was discussed by tests on saturated original loess,and the liquefaction mechanism of saturated original loess was analyzed from the viewpoint of microstructure.The results of tests indicate the structure of saturated loess,which doesn't slump,is meta-stable and the force of earthquake can cause loess structure to failure.Larger volume strain may be caused by collapse and shear shrinkage.The increasing curves of pore-water pressure can be fitted in modified A-curves presented by the authors.The parameterβimplies the influence of magnitude of dynamic stress on the development of porewater pressure,volume strainυreflects the influence of moisture slump on the development of pore water pressure,and the model of curves is controlled by the combination of different βandυvalues.By means of the liquefcation mechanism presented in the paper,we can solve the reasons why loess in Tajik and Haiyuan earthquakes can flow like a fluid in the gentle slope.
The increasing rhythm of pore water pressure was discussed by tests on saturated original loess,and the liquefaction mechanism of saturated original loess was analyzed from the viewpoint of microstructure.The results of tests indicate the structure of saturated loess,which doesn't slump,is meta-stable and the force of earthquake can cause loess structure to failure.Larger volume strain may be caused by collapse and shear shrinkage.The increasing curves of pore-water pressure can be fitted in modified A-curves presented by the authors.The parameterβimplies the influence of magnitude of dynamic stress on the development of porewater pressure,volume strainυreflects the influence of moisture slump on the development of pore water pressure,and the model of curves is controlled by the combination of different βandυvalues.By means of the liquefcation mechanism presented in the paper,we can solve the reasons why loess in Tajik and Haiyuan earthquakes can flow like a fluid in the gentle slope.
引文
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9犦段汝文,王峻,李兰.饱和黄土振动液化问题探讨犤A犦.第五届全国土动力学学术会议论文集犤C犦.大连:大连理工大学出版社,1998.144-148.
10犦白铭学,张苏明.高烈度地震时黄土地层的液化移动犤J犦.工程勘察,1990,22(6):1-5.
2犦谢定义.黄土力学特性与应用研究的过去、现在与未来犤J犦.地下空间,1999,19(4):273-284.
3犦王兰民,刘红炎,李兰等.饱和黄土液化机理与特性试验研究犤J犦.岩土工程学报,2000,22(1):89-94.
4犦IshiharaK,OkusaS,OyagiN,etal.Liquefaction-inducedflowslideinthecollapsibleloessdepositinSovietTajik犤J犦.Soilsandfoundations,1990,30(4):73-89.
5犦石兆吉,王兰民.土壤动力特性-液化势及危害性评价犤M犦.北京:地震出版社,1997.
6犦张振中.黄土地震灾害预测犤M犦.北京:地震出版社,1997.112-130.
7犦张建民,刘公社.动荷载下饱和砂土和无粘性土孔压计算模型的分析研究犤A犦.第三届全国土动力学学术会议论文集犤C犦.上海:同济大学出版社,1990.231-235.
8犦李兰.饱和黄土动力特性的几何探讨犤A犦.第五届全国土动力学学术会议论文集犤C犦.大连:大连理工大学出版社,1998.133-138.
9犦段汝文,王峻,李兰.饱和黄土振动液化问题探讨犤A犦.第五届全国土动力学学术会议论文集犤C犦.大连:大连理工大学出版社,1998.144-148.
10犦白铭学,张苏明.高烈度地震时黄土地层的液化移动犤J犦.工程勘察,1990,22(6):1-5.
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