The Mechanical Properties Of Corrugated Steel-Concrete Composite Structures And Application In Tunnels

According to the "13th Five-Year Plan" of the Ministry of Communications for the Development of Modern Integrated Transportation System,by 2020,the total mileage of highway in China will reach 5 million kilometers,and the number of mountain tunnels under construction or proposed is huge.The mountain tunnels adopts a composite lining generally,with anchors and shotcrete as the initial support of the flexible,and reinforced concrete as the rigid secondary lining.The traditional reinforced concrete lining has many defects,such as large thickness,complex working procedure,poor crack resistance,easy to crack,water leakage and so on.The combination of corrugated steel and concrete structure has the advantages of high strength,excellent tensile performance and good compressive performance of concrete.It is used in tunnel lining,with the construction technology of factory prefabricated corrugated steel plate,field assembly and pouring concrete,which has the advantages of small thickness,high strength,easy construction and easy maintenance.Based on the background of vigorous development of the mountain tunnels and the vigorous implementation of assembled construction in China,and relying on the Xia Yuan Tunnel Reinforcement Project in Yong Kang City,Zhejiang Province,it uses the theoretical analysis,laboratory tests and numerical simulations to study the mechanical properties of corrugated steel-concrete composite structures and their applications in tunnels,which has strong theoretical and practical significance.The major contents and conclusions include:(1)Based on the theory of composite beams,the mechanical properties of corrugated steel plate-concrete composite structures and the effects of different combinations on their mechanical properties are analyzed.It is found that compared with the concrete slab of the same thickness,the compression resistance and bending stiffness of the corrugated steel-concrete composite structure are significantly improved,and the effect of improving bending rigidity is much higher than the compressive stiffness.For the same corrugated steel plate,the increase of the thickness of overlying concrete has a significant effect on the stiffness of the structure,but with the increase of the thickness of concrete,the bearing capacity advantage of the composite structure gradually weakens.For corrugated steel plate with the same thickness,the mechanical properties of corrugated steel plate with large wave distance are better than those of corrugated steel plate with wavelet distance.(2)The indoor experiment was used to study the failure mechanism of corrugated steel-concrete composite beam and the influence of corrugated steel plate thickness,wave shape,shearing nail and steel mesh on the mechanical properties of corrugated steel-concrete composite beam.The experimental results and finite element simulation results are compared and analyzed.Laboratory tests show that the corrugated steel plate-concrete composite beams undergo three stages of elasticity,working with cracks and failure during loading.The cracks first appear near the loading point or in the pure bend section.With the increase of load,the micro cracks extend upward and the width increases.One of the cracks develops into a penetrating crack,and the concrete in the compression zone collapses.The setting of shearing nails can make corrugated steel plate and concrete work together better,and effectively increase the bearing capacity of composite structures.The setting of reinforcing bar net can effectively restrain the cracking of concrete and increase the bearing capacity of composite structure.The finite element simulation results agree well with the measured results,which verifies the correctness of the finite element model and lays a foundation for the tunnel lining design below.(3)Based on the reinforcement and reconstruction project of the Xia Yuan Tunnel,the application of the corrugated steel-concrete composite structure in the lining of the mountain tunnel was studied.Based on the design criterion,the internal force and deformation of corrugated steel plate-concrete composite lining are analyzed by using finite element software ABAQUS,and the stress,deformation characteristics and strength safety factor of lining with different thickness are compared.The lining with reasonable force and economic performance and thickness of 35 cm is selected for engineering application.The construction technology of corrugated steel plate-concrete composite lining is put forward,which provides reference for engineering implementation.