超深厚覆盖层中深埋细粒土地震残余变形特性振动三轴试验研究

Dynamic Triaxial Tests on Seismic Residual Deformation Characteristicsof the Fine-Grained Soil in Super-deep Overburden Layer

摘要:

土石坝(超)深厚覆盖层地基中的深埋细粒土抗地震残余变形能力较差,尤其是在土层厚度较大时,覆盖层地基连同坝体在强震作用下可能会产生较大的地震沉陷。针对我国西部某大型土石坝工程,对超深厚覆盖层地基中深埋粉砂层土的地震残余变形特性进行三轴试验研究。研究表明:试验土料级配曲线与相应土层各钻孔平均级配曲线很接近,试验土料的颗粒级配对实际土层的颗粒组成特性具有代表性;试验土料的地震残余变形特性主要受土体密度、固结条件和围压力条件等控制,尤其是固结比对土体地震残余变形特性影响较大;各因素对土体残余体积变形特性和轴向变形特性的影响规律有所差异。

Abstract:

The seismic capacity of residual deformation of the fine-grained soils which are buried deeply in super-deep overburden layer is poor, and a great seismic settlement of dam-foundation system may be produced by the earthquake when the thickness of soil layer is large.So it is significant for the anti-seismic design of dam to study the seismic residual deformation characteristics of soil and determine the corresponding characteristic parameters.In the paper, a series of dynamic triaxial tests on silty sands buried deeply in the super-deep overburden layer foundation of an earth-rock fill dam in China are carried out, and the seismic residual deformation characteristics of soils in earthquake are analyzed.The results show that:(1)the grading curve of testing soil is consistent with the mean grading curve of corresponding drill on field soils, and the grain composition properties of field soils can be represented by the testing soil;(2) the seismic residual deformation characteristics of testing soil is influenced by the density of soil and the stress condition, and the consolidation ratio is a significant influencing factor;(3) the influencing laws of factors on axial deformation characteristics and those on residual volumetric deformation of soils are different.