It is important to set reasonable tunneling parameters according to the ground conditions to reduce the deformation of existing tunnels, since the close crossing of new shield tunnels is likely to cause deformation in the adjacent existing tunnels. The K-means clustering algorithm was proposed to explore the correlation between tunneling parameters and surface settlement, and the optimal number of clusters was selected by using the sum of squared errors (E_SSE) to measure the clustering quality. Through cluster analysis on the field monitoring data of the test section, three cluster centers were obtained. Finally, the optimal combination of tunneling parameters for mud-water balanced shield construction in water-rich round gravel strata was proposed. The optimal combination of tunneling parameters was verified by combining the parameter setting values of the actual underpass section and the deformation of the existing tunnel. The results show that ① the optimal combination of tunnelling parameters for mud-water balanced shield construction in water-rich round gravel strata is an average torque of 2 005 kN·m, a thrust of 14 380 kN, a tunnelling speed of 17.5 mm/min, and a difference in inlet and outlet mud flow of 57 m³/h; ② after the optimal combination of tunnelling parameters is adopted, the vertical deformation of the existing tunnel near the underpass section is controlled within 0.58 mm, which achieves a relatively ideal deformation control effect.