Arching effect of soil ahead of working face in shield tunnel in sand with various depths

The soil arching effect is closely related to the supporting force and depths during tunneling construction. The soil arching effect was studied experimentally considering various depths of embedded tunnel and densities of the sand layer. The displacement of sand particles and development of soil arching near the face of excavation were analyzed. The development of soil arching and the its failure under various depths were revealed. Comparing with the laboratory tests, the two-dimensional particle flow code (PFC^2D) was employed to simulate the soil arching effect. The results show that the development of soil arching under different depths are the same, closely related to the supporting force and the ground settlement. The failure of soil shows funnel shape at low density, and strip shape at high density. The range of soil arching increases with the increase of depths. The change of particle contact force, porosity and average soil pressure are the same via PFC^2D simulation for various depths. Finally, the conclusion is drawn that the soil arching effect obtained from the laboratory tests is similar to that of PFC^2D simulation.