Abstract
Tunnel construction will inevitably change the surrounding soil’s original stress and displacement fields, affecting the surrounding piles. In addition, the lateral displacement of the soil at the subway tunnel’s face is symmetrically distributed along the tunnel’s central axis, which is greater in the center and smaller on both sides. Therefore, the protection of existing piles and providing a reasonable reinforcement plan have become the focus of attention. Taking a section of Tianjin Metro Line 3 as the research object, this paper studies the influence of the shield tunnel excavation process on the existing pile foundation through three-dimensional finite element simulation. The model has been verified through field monitoring data. Then, parameter analysis has been carried out for two reinforcement measures: grout reinforcement and isolation pile construction. According to the research results, the impact of shield construction on the pile foundation is mainly within the range of twice tunnel diameter to the pile foundation from the front and back of the tunnel face. In addition, the grouting reinforcement has better control of the vertical displacement of the existing pile foundation. The construction of isolation piles can better control the lateral displacement of the existing pile foundation. Have certain reference significance for similar projects.
Highlights
Due to rising urban population density and severe traffic congestion, Chinese tunnels have seen remarkable growth in recent years [1,2], with more tunnels being built as subsurface developments [3,4,5,6,7,8]
During the shield tunneling process, research and analysis of the impact of shield excavation on the pile foundation, the excathe pressure of the shield machine on the tunnel face to simulate the pressure of the earth is vation footage withinstress
The other parameters are simulated according to the actual situation, lyzing the influence of tunnel construction on the deformation of the pile foundation
Summary
Due to rising urban population density and severe traffic congestion, Chinese tunnels have seen remarkable growth in recent years [1,2], with more tunnels being built as subsurface developments [3,4,5,6,7,8]. Improving the self-supporting capability of surrounding soil and controlling deformation can effectively lessen the impact of tunnel construction on the surrounding environment and, at the same time, extend the service life of the tunnel during operation [5]. Since tunnel excavation and support may significantly influence the surrounding piles, reinforcing the surrounding piles is a significant problem [10,11]. A 3D finite element model is provided to analyze the displacement reinforcement effect through two different reinforcement measures on the pile foundations. The 3D model was verified by field test data, and the deformation degree of the existing pile foundation was analyzed as the shield tunnel was excavated. The effects of the two reinforcement measures on the displacement of the pile foundation under different parameters were analyzed and compared
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