Double Sidewall Combined Step Method for Ovoid Structured Tunnels with Additional Large Legs at the Lower Steps Research on Construction Technology

Abstract

For weak surrounding rock and poor geology large section tunnel excavation is easy to collapse, tunnel support difficulties and other issues, relying on a V-class surrounding rock up and down double-layer four-center horizontal elliptical structure tunnels, the proposed lower step at the addition of a large arch foot of the double sidewall combined with the construction technology of the step method, through the field experiments show that the technology on the surrounding rock disturbance is small, strong settlement resistance, process alternation, thus greatly improving the construction safety and the degree of machinery, while also saving construction costs. Mechanization degree, but also save the construction cost. This technology has certain reference significance for the construction of similar complex tunnels.