Researches On The Bearing Capactity Of The Reducible Joint With Cement-Asphalt Mortar For Raodway Support

Up to now, the joint for the reducible support made of U-steel has still been used for the steel tube concrete support. Consequently, the bearing capacity for the steeltubeconcrete support cannot be brought into full play and the total bearing capacity is not desirable.First, to solve the problem, a reducible joint made of still tube filled with cement-asphalt mortar is proposed. For the earliest possible application of the joint, a suitable mixture ratio should be deduced and in accordance to the ratio, the mortar can be mixed with appropriately proportions of cement, asphalt and sand to fill the still tube. Then affected by the rated working resistance, the mortar mixture will be emitted through spores out of the surface of the steel tube. To obtain such desirable performances, investigations should be made into the optimal mixture ratio of the mortar, the optimal bearing capacity of the joint and the optimal area of the spore through the surface of the joint tube. In this aspect, the preliminary experiments have been conducted to investigate the impacts on the compression strength and the deformation by the quantity of emulsified asphalt, the quantity of cement and the diameter of the sand grain so that a satisfactory mortar can be mixed up.Through experiments with the compressibility of the joint, the axial stress at the time for mortar to emit through the spores out of the surface of the tube could be determined and serve as a parameter for designing the sliding resistance for the reducible support. Through experiments with the compressibility of the joint, the axial stress as a function of the area of the spore can be deduced by changing the area of the spore. Along this line, the area of the spore can be optimized. Through theoretical analysis, this paper discusses yielding joint after compressive shrinkage on the bearing performance of the concrete-filled steel tube compressible support effect.