Mechanical Behaviors of Steel Segment Support Structures for TBM-Excavated Coal Mine Tunnels: Experimental and Numerical Study

In order to solve the problem of surrounding rock support difficulties encountered during TBM excavation in weak strata in coal mines, a steel segment support structure for TBM-excavated tunnels in coal mines was proposed. Full-scale model tests of the steel segment support structure were conducted under different lateral stress coefficients. The deformation and failure modes, bearing capacity, and strain distribution characteristics of the proposed roadway support structure were studied, and the factors influencing the bearing capacity of the support structure were determined, revealing the mechanism of the instability and failure of the support structure. Subsequently, numerical tests of the support structure were conducted to obtain parameters such as the axial force and bending moment, which were difficult to monitor in the full-scale model tests. The results showed that the support structure first experienced local instability at the joints and mid-span, leading to overall instability of the structure. The ultimate bearing capacities of the support structure were 3,972.2 kN and 2,763.2 kN for lateral stress coefficients of λ = 1.0 and 1.5, respectively. The ultimate bearing capacity decreases exponentially with increasing lateral stress coefficient, highlighting the importance of considering tectonic stress in design. Design parameters analysis reveals that rib plate thickness significantly influences bearing capacity, followed by rib plate width, while ring plate thickness has a minimal impact.