Experimental Study On Mechanical Performance Of Buried Corrugated Steel Arch Bridge With A Relieving Slab

The buried corrugated steel arch bridge has been widely used in highway engineering.In order to improve the mechanical performance and increase the scope of application,concrete relieving slabs have emerged as an important structural measure.On the one hand,the load is transferred to the soil and corrugated steel through the slabs.The “plate effect” of the slabs can be used to avoid the damage of the soil.On the other hand,the relieving slab can exert the load diffusion effect of the high-fill soil with a small thickness,reducing the internal force of the corrugated steel plate because of the greater rigidity and strength.At present,there are few researches on concrete relieving slabs at home and abroad.It is necessary to study the stress of the buried corrugated steel arch bridge after adding relieving slabs.The main research contents and results of this article are as follows:(1)A static load test was carried out on a 5-m-span overlying corrugated steel arch bridge with or without slab.There are 14 conditions include 3 types of fill thickness and3 loading conditions.The results show that the presence of relieving slab can significantly improve the mechanical performance of corrugated steel arch bridges.The deformation under live load is reduced by at most 86.2%,and the stress is reduced by at most 68.0%.The lower the fill thickness,the better the effect.The relieving slab has little effect in uniform loading conditions.(2)The finite element model was established using the finite element software ABAQUS.The finite results are compared with the test data and the parameter analysis was carried out.The results show that the thickness of the relieving slab has the greatest influence,and it is generally more appropriate to take about 20 cm.The longer the length of the slab beyond both sides of the span,the better the effect.The higher the position of the slab in the soil layer,the smaller the stress and deformation of the structure.But the reinforcement is needed when it is arranged on the top of the soil layer.For structures with different line types,the smaller the vertical stiffness,the more significant the load reduction board effect.(3)The load spreading mechanism of relieving slab is analyzed.The law of diffusion load of relieving slab is studied through model bridge test data and finite element simulation results.The stress diffusion angle of relieving slab is calculated with reference to the relevant theory of double-layer foundation.(4)A comparative analysis of the live-load effect calculation methods of buried corrugated steel arch bridges at home and abroad is carried out.It is considered that it is still necessary to check the bending stress according to the calculation method even if the fill meets the requirements of minimum covered soil thickness.Based on the method of converting the equivalent soil layer thickness by the stress diffusion angle of the relieving slab,the live-load effect calculation formula of the relieving slab is proposed.And the relevant design calculation suggestions are given.