Structural and Material Design of Composite Pavements in Road Tunnels

A mechanical calculation model of tunnel composite pavement was established using finite element software ABAQUS. The shear stress and horizontal tensile strain in the asphalt layer, the horizontal tensile stress in the concrete layer as well as the interlaminar shear stress were selected to be the key indexes. The mechanical calculation results show that with the increase of the thickness of the asphalt layer, its maximum shear stress increases and its tensile strain increases first and then decreases, while the interlaminar shear stress decreases. The maximum horizontal tensile stress in the concrete layer decreases with the increase of the thickness of concrete layer and the modulus of bedrock. Besides, the maximum horizontal tensile strain in the asphalt layer decreases when increasing its thickness. The thickness design methods of the asphalt layer are put forward based on the shear stress index and horizontal tensile strain index as well as interlaminar shear stress index. The thickness of an asphalt layer between 8cm and 10cm is verified to be reasonable. The thickness of the concrete layer is mainly to meet the functional requirements. In order to improve the service life, a minimum thickness of 40cm is recommended.