Calculation method for earth pressure and deformation of transverse pipe roof considering micro-arching effect

Pipe curtains are often used for pre-reinforcement to control surface settlement when excavating shallow-buried, large-span tunnels. There are two types of pipe curtain installation methods: longitudinal and transverse. The transverse pipe curtain construction can form a rigid transverse bearing system before tunnel excavation. This study investigates the deformation development of the pipe curtain, the soil pressure acting on the pipe curtain. The results indicate that the pattern of the deflection deformation of the pipe curtain is similar to the pattern of surface settlement. Considering the effect of soil arching between the pipes, a multilayer parabolic curve is used to characterize the shape of the soil arch. The soil arch can inhibit ground relaxation and reduce surface settlement. Based on the stress deflection theory, a multilayer parabolic arch model is established, and a method for calculating the loose soil pressure above the transverse pipe curtain is proposed. Combining this calculation method with the elastic foundation beam model of the Pasternak theory, a deformation calculation method for the pipe curtain at different excavation stages is developed. This method is compared and validated with field measurements and numerical simulation results. The proposed calculation method provides support for the design of transverse pipe curtains.