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.