Differential Analysis and Prediction Optimization of Ground Surface Settlement Induced by Quasi-Rectangular Shield and Pipe Jacking Tunnelling

The shield method and pipe jacking method will impact the ground surface and surrounding settlement during tunnel construction. Due to their different tunnelling principles and their cross-section characteristics, the impact on the stratum is often different. To study the differences between the two construction methods on ground surface settlement, numerical simulations, Peck empirical formulas, and field measurement data were used for analysis and comparison in this work. Two correction coefficients α and λ are introduced for correction on the basis of the DOT Peck formula, and the analysis of sensitivity factors for the ground settlement for the two construction methods is carried out. The numerical simulation results show that the ground settlement induced by pipe jacking construction is smaller than that of the shield, and this simulation result is confirmed by the field measurement result. When λ is selected from 0.85 to 0.91 and α from 1 to 1.1 for the shield project, 1.2 to 1.4, and 1.4 to 1.6 for the pipe jacking project, the modified formula can better predict the ground surface settlement. According to the sensitivity factor analysis, grouting pressure and elastic modulus of grout material exert a more significant influence on pipe jacking construction. The retreat of the pipe section caused by the tunnelling pressure difference will lead to 0 mm ∼ 1.93 mm fluctuation on the ground surface.

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