A solution to dynamic response of cylindrical lined cavity under internal transient load is one of the classical soil dynamics problems. Most previous literatures about the problem assumed that soil surrounding with cavity is an elastic medium or full-saturated poroelastic medium. In fact

perfectly elastic and completely saturated soil does not exist in practical engineering. The lining structure and its surrounding soil are treated as an ideal elastic medium and a nearly saturated poroelastic medium

respectively. On the basis of Newton’s second law

Darcy’s law and Biot’s theory

the governing equation of nearly saturated soil is derived. According to boundary conditions

solutions for the radial displacement

hoop stress and pore stress of the lining and saturated soil are obtained in Laplace transform space; and then they are transformed to solutions in time domain using inverse Laplace transforms numerical method. Also

the influence of the saturation degree ( ) on the dynamic response of the lining and soil is investigated. It is indicated that the saturation degree has a less effect on the radial displacement and hoop stress when 95% 99% and has a significant influence on them when 99% 100%. But the saturation degree has much more effect on the pore stress than on the former two. The same conclusion can be drawn that the influence of saturation degree on the attenuation of dynamics response along radial direction. The saturation degree has a less effect on the radial displacement and hoop stress when 95% 99% and has a significant influence on them when 99% 100%. It also indicates that the saturation degree on the attenuation has more effect on pore stress than that of raidial displacement and hoop stress.