The foundation pit excavation and dewatering break the equilibrium stress field of the surrounding soil layer and negatively affect the underlying shield tunnel. The analytical solution of the longitudinal deformation of the underlying tunnel caused by foundation pit excavation and dewatering is proposed using a two-stage analysis method. In the first stage

Mindlin elastic solution and effective stress principle are used to calculate the additional stress caused by excavation and dewatering. In the second stage

the shield tunnel is treated as a Timoshenko beam resting on the Pasternak foundation to simulate the interaction between the tunnel and soil. The analytical solution of the longitudinal tunnel deformation is derived from the superposition method. By comparing with the monitoring data of engineering examples

the correctness of the proposed method is verified

and the influence of the excavation length

width

depth

tunnel burial depth

dropdown

and relative position of the foundation pit on the longitudinal displacement of the tunnel is further analyzed. The results show that with the increase of excavation length

width

and depth

the maximum uplift of the tunnel increases. The tunnel deformation decreases with the increase in tunnel burial depth. With the increase of the dropdown

the uplift decreases

and the settlement value increases. With the increased distance between the tunnel axis and the foundation pit center

there are a decreasing area of the uplift

an increasing area of the settlement

and a decreasing area of settlement.