固结压力相关的黏土动力特性模型研究及应用  

Research on consolidation pressure correlated dynamic properties model of clay and its application

作　　者：刘方成[1] 尚守平[2] 王海东[2] 

机构地区：[1]湖南工业大学土木工程学院,湖南株洲412008 [2]湖南大学土木工程学院,长沙410082

出　　处：《岩土力学》2010年第5期1437-1444,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.50808078);湖南省自然科学基金(No.08jj4016);教育部博士点基金(No.20070532090)

摘　　要：对一种粉质黏土进行了不同固结压力下的循环单剪试验,得到了相应各固结压力下的动剪模量和阻尼比随动剪应变幅值非线性变化的Gd-γd曲线和D-γd曲线,并对其进行了归一化。试验结果表明,即使是归一化以后的动力特性曲线,仍然因固结压力不同而出现差异;固结压力越大,Gd/Gdmax-γd曲线衰减越慢,而D/Dmax-γd曲线增加也越缓。通过建立最大动剪模量、最大阻尼比和参考剪应变与固结压力之间的试验关系式,建议了一种实用的固结压力相关的黏土动力特性模型。最后,通过算例表明,场地土体动力特性随固结压力而变化的特征不但会影响场地地震反应的幅值,而且将影响其频谱特性,且场地覆盖层厚度越大,影响越强烈。Cyclic simple shear tests are conducted on a silty clay with different axial consolidation pressures;and nonlinear dynamic property curves,Gd vs.γ d curve and D vs.γ d curve,of soil under different test consolidation pressures,where Gd,γ d and D are dynamic shear modulus,dynamic shear strain radio and damping ratio respectively,are obtained.Results indicate that even normalized dynamic property curves of soil under different consolidation pressures exhibit differences.Along with the build up of consolidation pressure,the degradation of Gd/ Gdmax-γ d curve slows down;and the increase of D/ Dmax-γ d curve delays.Based on the experimental relationship between maximum dynamic shear modulus,maximum damping ratio,reference shear strain and the consolidation pressure separately,a novel consolidation pressure correlated dynamic property curve model of clay is proposed.Application of the consolidation pressure correlated model for site response is carried out.Results indicate that the property of soil dynamics varid with the consolidation pressure will affect not only the magnitude but also the frequency spectrum properties of the site response,and the thicker of overlay,the more obvious of the affects.

关 键 词：固结压力 土动力特性 非线性 粉质黏土 循环单剪试验 

分 类 号：TU411.8[建筑科学—岩土工程]