Analytical Solution for Surrounding Rock Pressure of Deep-Buried Four-Hole Closely Spaced Double-Arch Tunnel

Research on the calculation method of deep-buried surrounding rock pressure is an important subject in engineering mathematics. The existing calculation methods are mainly the two-hole closely spaced tunnel, double-arch tunnel, three-hole closely spaced tunnel, and three-arch tunnel. The four-hole closely spaced double-arch tunnel has the characteristics of both the double-arch tunnel and closely spaced tunnel, and its surrounding rock pressure distribution is more complicated. In this paper, the research is carried out based on Protodyakonov's theory and the concept of process load. The influence of the post-construction tunnel on the supporting structure of the pre-construction tunnel is also considered. The calculation model of the surrounding rock pressure of the deep-buried four-hole closely spaced double-arch tunnel is established, and the calculation formula of the surrounding rock pressure is deduced and verified. Finally, the influences of the rock column parameters, excavation procedure, tunnel span, and middle partition wall on the surrounding rock pressure are analyzed.