Equivalent nonlinear model is usually applied in seismic response analysis. The shear modulus and damping ratio are two important properties in this model. Highly weathered granite is common in large engineering. It is essential to study dynamic properties of highly weathered granite. The shear modulus and damping ratio of highly weathered granite are studied with GDS resonant-column; as its the capability is excellent

it is popular in the world. The confining pressure and pore water pressure to consolidate can be controlled well by GDS RCA. After the end of sample’ consolidation

shear modulus and damping ratio can be given by experiment in the state of this effective stress. Changing confining pressure and pore water pressure

resonant frequency

shear modulus and damping ratio can be given with another effective stress. In different effective stresses

variation of shear modulus and damping ratio can be observed. And fitting curves of shear modulus and damping ratio that are put forward by Hadin-Drnevich[1] are turned out on the basis of experimental data. The authors discuss the damping mechanism of highly weathered granite sample by amfusing frictional theory. It can be seen that resonance frequency of the sample’s system has a positive correlation with shear strain

but sample’s damping ratio has a negative with shear strain. The effective stress can have impact on both sample’s shear modulus and damping ratio. However

pore water pressure can only act on damping ratio.