Modification of the Peck Formula for Double-Line Large-Diameter Slurry Shield Tunnels in Composite Strata

With the acceleration of urbanization, underground space development has become an important way to relieve the pressure of urban traffic. In composite formation, the construction of a double-line large-diameter mud-water shield tunnel faces complicated geological conditions and construction problems. Based on the measured surface settlement data of a double-line tunnel project in Hangzhou, this study adopts a mathematical method to perform regression analysis and introduces the correction coefficient α of the maximum surface settlement and the correction coefficient β of the width of the settlement trough to correct the double-line Peck formula. Meanwhile, combining the superposition principle, an applicable correction method for the superposed section of the double-line tunnel in composite formation is proposed. In order to accurately predict the ground settlement law of double-line large-diameter mud-water shield tunnel construction in composite formation. The results show that there is a great difference between the measured value and the predicted value of the Peck formula of the double-line large-diameter mud shield before correction. Examples show that the superposition section correction method can effectively improve the fitting degree of the superposition section prediction curve when the center distance L of the two-track tunnel is greater than (i left +i right). By comparing the corrected coefficient range ofthe Peck formula with different diameters, it can be seen that the large-diameter shield is better than the small-diameter shield in vertical settlement control, and the distribution range of the corrected coefficient of sedimentation tank width is larger than that of the small-diameter shield. The research can provide a reference for the design and construction of large-diameter shield tunnels in China.