Abstract
Shield tunnels will inevitably pass through viaduct piles at a close distance due to the extensive construction of subways and viaducts in the city. In order to understand the influence of shield tunneling on the deformation of existing pile foundation and grouting protection measures, based on an engineering case, Changsha Metro Line 5 (from South Gaoqiao station to Guitang station), a three-dimensional finite element model was established to analyze the deformation of bridge pile using grouting protection wall with different depths and shapes when the shield tunnel is under construction. The analytical results indicate that the grouting protection wall can effectively reduce the pile displacement; especially the grouting depth is 3 m below the bottom of the tunnel. Moreover, the L-shaped grouting protection wall can effectively reduce the longitudinal displacement of the piles. The present findings may provide a reference for the design and construction of shield tunnels passing through viaduct piles.
Highlights
With the continuous development of urbanization, in order to solve the ground traffic congestion, the viaduct and subway become important parts of urban infrastructure
Due to traffic route design and urban space constraints, shield tunnels often need to pass through existing viaduct piles. e excavation of shield tunnel may cause the deformation of surrounding soil [1,2,3,4,5,6,7,8,9,10], affecting the existing pile foundation
Previous research focused on the investigation of the influence of shield tunneling on adjacent pile foundations by theoretical derivation and calculation analysis [39,40,41,42,43,44,45,46]
Summary
With the continuous development of urbanization, in order to solve the ground traffic congestion, the viaduct and subway become important parts of urban infrastructure. Several scholars proposed protection measures for the pile foundation to reduce the adverse effects caused by shield tunneling [47,48,49,50,51,52,53,54,55]. Li et al [55] proposed four kinds of protective schemes to guarantee the safety of existing grouped piles of Shiyou Bridge during tunnel construction and found that the deep-hole grouting scheme has a better control effect on the lateral deformation and bending moment of the piles. Four grouting schemes were proposed to control the deformation of the pile foundation for the tunnel passing through the viaduct pile. An “L”-shaped grouting isolation scheme is proposed, which can effectively protect the adjacent bridge piles and make the shield drive smoothly
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