Abstract：The large-scale model testing is one of the important methods to research style of structural internal force and stability of surrounding rock in double-arch tunnel. Based on the Xiaojinkou double-arch tunnel engineering of Guangzhou—Huizhou Expressway，the construction method，styles of structural internal forces and the stability of surrounding rock of double-arch tunnel are studied in detail under the condition of surrounding rock types II and III. By the model testing，a new method，i.e.，central-heading expanding method，has been suggested. The surrounding rock is seldom disturbed when the tunnel is constructed by the central-heading expanding method. The three-heading method，double-heading method and central-heading expanding method have been studied by model testing. It is found that the maximum radial displacement take places at the arch and the sidewall. The model of internal force for the secondary lining and the laws of the deformation and the stability for the surrounding rock have been set up firstly in the double-arch tunnel. The results can offer references to the design and construction of double-arch tunnel.
