Study On The 3.D Fracture Mechanism Of The Dangling Pavement Slab Along The Rive In The Mountain Area

The mountains and hills are the main landforms in the southwest regions, where there is an abundant rainfall in summer and it provides the best geographical advantages for the inoculation of geological hazard, such as torrential flood and mudslide. The highway is near the mountain and by the river, where the geological hazards are always being repeated. It has suffered a large loss caused by the highway flood. The concrete dangling pavement slab is one of the common forms in typical situations of the highway water ruin. The concrete dangling pavement slab along the river is researched in this paper. Adopting the equivalent composite materials theory, the finite element modeling, the elastic foundation and thin plate theory, fracture mechanics and material mechanics, the 3.D fracture mechanism of the concrete dangling pavement slab under weight and vehicle loads is analyzed. Based on the degree of dangling, crack condition of the road, the ultimate bearing capacity of the dangling pavement slab is calculated. Meanwhile the safe area of driving is marked off. By means of traffic control, the traffic loads and the driving areas are limited in order to prevent the dangling concrete pavement slab fracturing suddenly and protect the life and property of people.The main achievements in this paper are as follows:(1)Based on the theory of composite materials, the mesomechanics method is used, referring the crack propagation regulation of the concrete dangling pavement slab, the formula of forecast model of the equivalent elastic modulus, which is transferred into two equivalent models, such as a 3.D combination model of serials and parallel model and a 3.D combination model of serials model have been gotten. On the basis of optimization, the reinforced concrete pavement slab is equivalent to homogeneous pavement slab, which will provide support for the finite analyses and theory analyses.(2)The ANSYS software is used to simulate the parallel dangling pavement slab and the dangling pavement slab from the corner, considering the dangling ratio, vehicle loads and vehicle location factors, the stress field distribution is analyzed, the maximum tensile stress distribution rule and the most adverse vehicle position have been gotten, which will provides reference for the theory analyses.(3)Based on the Winkler’s elastic foundation and thin plate theory, referring the thought of Westergaard in solving the complete infinite slab’s stress field, the parallel dangling pavement slab is simplified as the complete pavement slab. Furthermore the tensile stress formula has been received on the shearing face.(4) The surface crack is set on the selected 3.D fracture model, and the ultimate bearing capacity of the dangling pavement slab under dead weight and vehicle loads is analyzed.(5)The rigid pavement’s load stress is calculated by using material mechanics, the tensile stress formula of the dangling pavement slab from the corner has been gotten. To combine the method of fracture mechanics, the surface crack is set on the selected 3.D fracture model, and the ultimate bearing capacity of the dangling pavement slab from the corner under dead weight and vehicle loads is analyzed.