Experimental Study on the Mechanical Characteristics of Assembled Elevated Arches Under the Action of Uplift at the Bottom of Mudstone Strata

In order to investigate the force characteristics of seven-part assembled back arch under the action of mudstone tunnel bottom drum, based on the similarity theory, through the straight shear test and uniaxial compression test, the mudstone similar materials conforming to the similarity ratio design are prepared, and the model test of the bottom drum of assembled back arch is carried out, and the mechanical characteristics of the lining surface stresses, axial forces and bending moments are analyzed under the action of the expansion of bedrock surrounding rock. The results showthat: under the action of base rock expansion, the maximum tensile stress of assembled arch is located at the side wall, which is the most dangerous cross-section of lining; the tensile stress at the center of the upper plate of the arch is larger, which is the most dangerous cross-section of the prefabricated arch; the side wall exhibits outward expanding deformation, and the arch roof and foot of the arch exhibits extrusion deformation towards the tunnel headroom; the axial force and the bending moment of the upper plate of the arch are tensile force and positive bending moment, respectively; and all of them are parabolic growth trend with the increase of the loading height. Parabolic growth trend. Through the study of mechanical characteristics of assembled upward arch in mudstone tunnel under the action of bottom drum, in order to provide a reference basis for the research and development and practice of assembled upward arch technology in mudstone tunnel.