Analysis of influence of double-line shield tunnel excavation on adjacent bridge piles
In order to study the influence of shield tunnel crossing the existing bridge pile closely,based on the engineering example of Hohhot metro line 1 crossing the drum tower overpass pile,the numerical model was established by ABAQUS,and the Mohr-Coulomb elastic-plastic theory was used to compare and analyze the influence factors of pile length,pile diameter,tunnel depth and pile top load.The results show that under the influence of soil disturbance in tunnel excavation,with the increase of pile length,pile diameter and pile top load,the horizontal displacement of the three piles are gradually reduced,and the bending moment of pile I and pile III are gradually increased.Since the pile II is located between the two tunnels,the bending moment of the pile is offset by the superposition effect of the left and right tunnels during the excavation,so that the bending moment of the pile does not change regularly.With the increase of the buried depth of the tunnel,the horizontal displacements of the three piles do not change regularly,but the bending moment of the piles increase significantly,and the maximum bending moment of the piles is within the range of the buried depth of the tunnel.When the buried depth of the tunnel is shallow,the excavation influence range is small,and the influence on the adjacent piles is small.Grouting reinforcement can effectively control the horizontal displacement of pile foundation and ground subsidence during tunnel excavation,but the control effect of horizontal displacement of pile foundation decreases with the decrease of net distance between shield tunnel and pile foundation.
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