分散性土动剪切模量影响因素的试验研究

分散性土耐冲蚀性低、抗渗性能差，在纯水中具有很高的分散性，严重威胁水利工程的安全。在分散性土的鉴别和改性方面已有很多成果，但分散性土动力特性的研究见诸报端的还很少。利用日本诚研社生产的DTC-199型电液伺服加荷往复扭剪三轴仪，对取自宁夏某碾压均质土坝的分散性土的动剪切模量进行了探索。通过改变试样的含水率、干密度和围压等初始条件，研究分散性土在不同试验条件下的动力特性及剪切模量的变化规律，并进行对比分析。得出：分散性土的动剪应力-应变关系符合Hardin-Drnevich双曲线模型；控制初始条件，当其他条件相同时，含水率越低，动剪切模量越大；干密度越大，试样动剪切模量越大；围压越高，其动剪切模量越大；初始剪切模量及最大动剪应力的变化规律与之相似。动剪切模量随动剪切应变的增大普遍呈衰减趋势。

Experimental research on factors influencing dynamic shear modulus of dispersive clay

The dispersive clay is a special soil which has low erosion resistance ability, impermeability, and high dispersion in pure water; it would cause serious harm to water conservancy construction. There have been many results on identification and modification of dispersive clay; but study of dynamic characteristics of dispersive clay is seldom reported in the newspapers. By using the DTC-199 dynamic torsional shear instrument to study the dynamic shear modulus of a kind of dispersive clay coming from a rolling soil dam in Ningxia. By changing the initial conditions such as moisture content, dry density and confining pressure and so on, to study its dynamic characteristics and its variation rules of dynamic shear modulus in different experimental conditions, then to compare and analyze the results. We can get that: dispersive clay’s dynamic shear stress-strain relations conform Hardin-Drnevich hyperbolic model; controlling the initial conditions, as other condition is the same, the lower moisture content, the greater dynamic shear modulus; the greater dry density is, the greater dynamic shear modulus is; the higher confining pressure is, the greater dynamic shear modulus is. Initial shear modulus and the maximum dynamic shear stress change as the same way. Dynamic shear modulus become smaller as dynamic shear strain increases. Compared with ordinary clay, the moisture content has greater impact on its strength and deformation.