As the characteristics of near-fault ground motion differs from those of the distant-fault one re- markably

a set of vertically double-layered metro tunnels in deep soft sites is investigated according to the seismic environment of Jiangsu province and the background of Nanjing metro project.By using the finite- element software ABAQUS

the system of soil-metro tunnels is idealized as a plane strain problem to mod- el the nonlinear dynamic interaction of the system.The stress

displacement and acceleration of the dou hie-layered metro tunnels are calculated respectively to be compared with those of a single-layer tunnel. Results prove that:the phenomenon that the stress on the outside-edge of the tunnel-wall is larger than that on the inside-edge is prevalent under near-fauh strong ground motion

and the stress is 1.4～3.4 times larger than that under moderate and strong Nanjing artificial earthquake waves.The dynamic stress of the double-layered tunnels is lower than that of the single-layer tunnel at corresponding positions while the horizontal relative displacement of the former is larger than that of the latter;and the horizontal rela- tive displacement at the top of the upper tunnel is 1.29～1.69 times as large as that of shallow buried sin- gle-layer tunnel.The acceleration at the bottom of the double-layered tunnels is more or less the same as that of shallow or deep buried single-layer tunnels

and their differences are within the limit of 10%.