基于二元介质模型的砂类土剪切波速试验研究

Experimental study on shear wave velocity of sandy soil based on binary medium model

为探究细粒质量分数Fc、相对密度D_(r)、初始有效围压σ′_(3c)对饱和砂类土剪切波速V_(s)的影响,基于二元介质模型,对具有不同Fc、D_(r)和σ′_(3c)的饱和砂类土进行了一系列均等固结弯曲元试验。结果显示:其他试验条件相同时,V_(s)随Fc的增大而减小;当D_(r)相同时,V_(s)与σ′_(3c)的相关性不随Fc的增大而改变;而当Fc相同时,砂类土的V_(s)随固结后孔隙比e_(c)的增大而减小的趋势与σ′_(3c)的大小无关。研究表明,V_(s)与单一指标Fc、D_(r)、σ′_(3c)或e_(c)没有单一的相关性,总体上砂类土的V_(s)随等效骨架孔隙比e^(*)_(c)的增大而减小,且两者呈较好的线函数关系,与Fc、D_(r)、σ′_(3c)或e^(*)_(c)值的大小无关,表明能综合反映砂类土颗粒组成、密实状态和粗细粒接触状态的e^(*)_(sk)是表征饱和砂类土V_(s)的一个有效物理特性指标。

In order to investigate fine content(Fc),relative density(D_(r))and initial effe_(c)tive confining pressure(σ′_(3c))on the shear wave velocity(V_(s))of saturated sandy soils,based on binary medium model,a series of isotropically consolidated bending element tests were performed on saturated sandy soils with different Fc,D_(r) andσ′_(3c).The test results show that an increase in Fc causes a de_(c)rease in V_(s) of saturated sandy soils with the same test conditions.At a fixed D_(r),the correlation between V_(s) andσ′_(3c) does not change with the increase of Fc.In addition,the difference ofσ′_(3c) does not contribute to the trend of the de_(c)rease of V_(s) with the increase of consolidated void ratio e_(c) of saturated sandy soils with a constant Fc.The analysis reveal that V_(s) has no single correlation with the single index Fc,D_(r),σ′_(3c) or e^(*)_(c).However,V_(s) de_(c)reases monotonically with the increase of the equivalent skeleton void ratio(e_(c)),and a line function relationship between V_(s) and e^(*)_(sk) is then obtained,which means,e^(*)_(sk),synthesizing the grain-size content of sandy soil,density state,and inter-grain contact,is an appropriate index of physical properties for evaluating V_(s) of sandy soils.