| With the “Carbon peaking and carbon neutrality strategy” and the concept of green construction,the development of the transportation industry is gradually showing the trend of green,efficient and intelligent.Cast-in-place cement concrete pavement has the shortcomings of long health period after pouring,difficult repair after damaging,and difficult disassembly after using.Precast concrete pavement slab in batch can save the health period of concrete pavement,reduce the noise pollution and environmental pollution caused by the field construction.In addition,the precast slabs can be disassembled and transported to another site for reuse.It is one of the important ways for the road industry to develop towards green and efficient.However,the research of precast cement concrete pavement was not systematic and lacked a unified reference standard,which restricted its further development.Therefore,it is of far-reaching significance to study precast cement concrete pavement from many aspects.In order to propose a design and construction method of precast concrete pavement that is easy to assemble,disassemble and conform to pavement strength,the size of the precast slab,the joint load transfer mechanism,the influence of the bottom caving state on the mechanical response of the slab and the hoisting mode of the slab were studied by means of theory,simulation and experiment.The main research contents and results are as follows:(1)The structural limit state of solid slab and circular hollow slab of precast concrete pavement under load was calculated and checked.It was determined that when the length of solid slab was 4m,the width was 3.5m,the thickness was 0.24 m,the circular radius of the hollow slab was 6cm,the height of the center of the circle was 14 cm,and the hollow rate was20%,both solid slab and hollow slab could meet the application requirements.(2)Taking the solid plate as an example,the displacement transfer coefficient of the flat joint,the trapezoidal groove joint,the dowelled joint and the Post-tensioned prestressed steel strand joint were compared.It was recommended that the solid slab adopted the combined joint made of trapezoidal groove and post-tensioned prestressed steel strand joint,and the hollow slab adopted the trapezoidal groove joint.A scaled model of trapezoidal groove hollow slab was established according to the size and joint of the hollow slab,and the hollow slab with the flat joint was used as the test control group for scaling test.The vertical displacement of trapezoidal groove hollow slab and flat joint hollow slab were tested and the joint load transfer coefficient was calculated.Then the load transfer capacity of trapezoidal groove and flat joint was compared from the experimental point of view,and the experimental results were compared with the simulation results.(3)Under the condition of slab bottom caving,the most unfavorable caving position of flexural tensile stress and vertical displacement of plate was determined,and the influence of five kinds of joint slabs on the caving was compared.The influence of surface modulus,base modulus,caving size and caving depth on the stress and load transfer of combined joint slabs was studied.The vertical displacements of trapezoidal groove hollow slab and flat joint hollow slab were measured under the condition of voids beneath slabs,and the test results were compared with the vertical displacements of slab bottom without emptying,which showed the influence of voids beneath slabs on slab vertical displacement and joint load transfer.(4)The lifting mode of solid slab and hollow slab with certain size was designed,and the influence of lifting point location,embedded lifting parts and lifting angle on slab lifting stress was studied.It was recommended that steel truss should be used to assist solid slab lifting,and steel wire rope should be used to pass through the hollow slab hoisting.Under the same hoisting mode,the advantages of hollow slab mass reduction could reduce the lifting stress. |
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