大连滨海粉质黏土剪切力学特性环剪试验

Shear Strength of Silty Clay in Dalian by Ring Shear Tests

以大连滨海地区典型粉质黏土为研究对象,利用大型高速环剪仪,针对不同法向应力和剪切速率条件下该粉质黏土大剪切力学性质的变化情况进行了试验。环剪试验结果显示:1)该滨海粉质黏土在正常固结状态下出现明显的应变软化现象,分析表明其应变软化特性主要与土中黏土矿物质量分数及其在剪切过程中的定向排列有关。2)在相同剪切速率下,峰值强度和残余强度随法向应力的增加而增大,峰值强度与法向应力之间表现出良好的线性关系。3)由于峰值强度产生过程中土体内部黏聚力的变化,峰值强度随剪切速率的增加而增大;残余强度变化与剪切速率具有一定的相关性,这与不同剪切速率下剪切带(面)处黏土颗粒定向排列程度不同有关。

The change of the shear mechanics properties of typical silty clay in Dalian Binhai area was tested at different normal stresses and shear rates by ring shear apparatus.Test results indicate that： 1） strain-softening phenomenon of silty clay was observed in normal consolidation state. It was shown that strain softening feature is mainly related to the mass fraction and directionality of clay mineral in the soil in the process of shearing.2）At the same shear rate, the peak strength and residual strength increase with the increase of normal stresses, and showed a good linear relationship between normal stress and peak intensity.3）Due to internal cohesive force of soil changes in the process of peak intensity, the peak intensity increases with the increase of shear rate;the residual strength and shear rate have certain correlation, which has a relationship with shear zone （surface） of clay grain orientation arrangement at different levels under different shear rates.