超深厚覆盖层中深埋细粒土动力变形和强度特性三轴试验研究
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摘要
土石坝(超)深厚覆盖层中的深埋细粒土难以完全挖除(换填),其在地震作用下的动力变形特性和强度特性是科研设计人员关注的问题。本文进行某大型土石坝工程超深厚覆盖层地基中的深埋粉砂层土动力特性三轴试验,研究其在地震荷载作用下的动力变形与强度特性,并为大坝—地基系统动力分析和抗震设计提供基础资料。研究表明:试验土料最大动剪模量和平均有效应力在双对数坐标中呈良好的线性关系,不同围压力条件下的模量衰减(阻尼比增长)曲线可以采用参考剪应变的方式进行归一,可用试验确定特定围压力条件下的模量衰减(阻尼比增长)曲线外延推求任意围压力条件下的相应曲线;试验土料在地震荷载作用下的动强度特性主要受土体密度、固结条件和围压力条件等控制,当土体处在不等向固结状态时,不同动力破坏标准下确定的土体动强度特性参数差异较大。
The dynamic deformation and strength characteristics of fine-grained soil in the superdeep overburden layer is the focus of engineers because soil buried deeply underground cannot be bulldozed easily.In this study,a series of dynamic triaxial tests is performed in silty sands buried deeply in the super-deep overburden layer foundation of an earth-rock fill dam,and the dynamic deformation and strength characteristics of soil in an earthquake zone are analyzed.The results show a strong linear relationship between the maximum dynamic shear modulus of testing soils and the mean effective stress of soils in the dual-logarithm coordinates system.The decay(increasing)curves of soil dynamic shear modulus(damping ratio)in various confined pressure conditions can be unified by the model of soil reference shear strain,and the decay(increasing)curves of soil in an arbitrary stress condition can be obtained through the extension of decay(increasing)curves of soil in testing stress conditions.The dynamic strength characteristics of testing soils is influenced by the density of soil and the testing stress condition;significant differences in the characteristic parameters of soil dynamic strength testing with various failure criteria are shown when the soil is the condition of unequal stress consolidation.
The dynamic deformation and strength characteristics of fine-grained soil in the superdeep overburden layer is the focus of engineers because soil buried deeply underground cannot be bulldozed easily.In this study,a series of dynamic triaxial tests is performed in silty sands buried deeply in the super-deep overburden layer foundation of an earth-rock fill dam,and the dynamic deformation and strength characteristics of soil in an earthquake zone are analyzed.The results show a strong linear relationship between the maximum dynamic shear modulus of testing soils and the mean effective stress of soils in the dual-logarithm coordinates system.The decay(increasing)curves of soil dynamic shear modulus(damping ratio)in various confined pressure conditions can be unified by the model of soil reference shear strain,and the decay(increasing)curves of soil in an arbitrary stress condition can be obtained through the extension of decay(increasing)curves of soil in testing stress conditions.The dynamic strength characteristics of testing soils is influenced by the density of soil and the testing stress condition;significant differences in the characteristic parameters of soil dynamic strength testing with various failure criteria are shown when the soil is the condition of unequal stress consolidation.
引文
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[2]中华人民共和国水利部.SL237-1999土工试验规程[S].北京:中国水利水电出版社,1999.Ministry of Water Resources of PRC.Code of Soil Test(SL237-1999)[S].Beijing:China Water Resource and Hydro-powder Publishing House,1999.(in Chinese)
[3]钱家欢,殷宗泽.土工原理与计算[M].北京:中国水利水电出版社,1996.QIAN Jia-hua,YIN Zong-ze.Geotechnical Theory and Calculation[M].Beijing:China Water Resource and Hydro-powder Publishing House,1996.(in Chinese)
[4]Hardin,Drnevich.Shear Modulus and Damping in Soils[J].Journal of the Soil Mechanics and Foundation,Asce,1972,98,(SM.7).
[5]刘小生,汪闻韶,赵冬.饱和原状砂土的静、动力强度特性试验研究[J].水利学报,1991,22(11):41-46.LIU Xiao-sheng,WANG Wen-shao,ZHAO Dong.Experimental Study on Static and Dynamic Strength Characteristics of Undisturbed Sand[J].Journal of Hydraulic Engineering,1991,22(11):41-46.(in Chinese)
[6]汪闻韶.土的动力强度和液化特性[M].北京:中国水利水电出版社,1997.WANG Wen-shao.Dynamic Strength and Liquefaction Characteristics of Soil[M].Beijing:China Water Resource and Hydro-powder Publishing House,1997.(in Chinese)
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