Abstract: Curved pipe jacking bottom curtain method is a new type of underwater shipwreck salvage technology. As this method adopts a new type of vertical small curvature radius pipe jacking, the theoretical calculation of variable-depth jacking force during the tunneling process and the disturbance to the hull and surrounding areas remain unclear. Based on the analysis of pipe-soil interaction, a more realistic pipe-soil interaction model is established by simplifying the shear failure of pipe and soil, and the theoretical thrust of vertical curved pipe jacking is deduced. The calculated thrust values from this model are compared with field-measured data and existing theoretical formulas, validating the rationality and accuracy of the proposed thrust calculation model. Additionally, a refined finite element salvage model for curved pipe jacking bottom curtain method is developed. By incorporating the theoretical thrust as input parameters into numerical simulations, the disturbance distribution law of surrounding soil layer and shipwreck during jacking process of curved pipe jacking bottom curtain method under different construction sequences is obtained. The results show that when the underwater curved pipe jacking is advancing, the pipe joint behind the shield head is mainly in contact with surrounding soil and causes friction, which is the largest resistance source in the jacking process. Unilateral construction and symmetric construction result in vertical ground settlements of −15 cm to −16 cm upon completion. However, symmetric construction induces more uniformly distributed ground disturbances, with significantly reduced disturbance and deflection on the shipwreck compared to unilateral methods. The thrust calculation model of the underwater curved pipe jacking bottom curtain method proposed in this paper is closer to the field measurement results. The research outcomes provide a theoretical basis for jacking force calculation and refined assessment of construction-induced disturbances in underwater curved pipe jacking bottom curtain method.

Key words: curved pipe jacking bottom curtain method, underwater shipwreck salvage, thrust calculation model, theoretical analysis, construction disturbance