Abstract: When the mining method is applied in metro station construction, several challenges are encountered, including difficulty in controlling ground deformation, long construction periods, and complex construction procedures. To address these issues, a collaborative support method that combines a small-diameter pipe roof with the permanent roof structure of metro stations is proposed, namely the small pipe-roof-top slab (SP-TS) method. A case study is conducted at Heping South Street station on Shenyang metro line 3, and the construction sequence of the SP-TS method for metro station construction is systematically described for the first time. Subsequently, a three-dimensional numerical model, validated by on-site monitoring data, is established to analyze the influence of excavation length, station span, pipe roof stiffness, and top slab elastic modulus on surface settlement. Finally, based on orthogonal experimental design and multiple linear regression analysis, a quantitative prediction model is developed to describe the relationship between support parameters (pipe roof stiffness and top slab elastic modulus) and surface settlement under different excavation lengths and station spans. The results indicate that: (1) surface settlement is most pronounced during the top slab construction stage, which is a critical phase for settlement control using this method; (2) surface settlement increases logarithmically with excavation length and station span, whereas it decreases logarithmically with pipe roof stiffness and top slab elastic modulus. The influence of pipe roof stiffness is particularly significant; increasing its stiffness from EI to 2EI reduces settlement by approximately 8.2 mm; (3) based on multiple regression analysis, a settlement prediction model is established to provide graded support parameter schemes for metro stations with different spans and excavation lengths.

Key words: small pipe-roof-top slab method, parameter matching, metro station, surface settlement, numerical simulation