| Compared with traditional reinforced concrete pipe culverts and other types of rigid culverts,corrugated steel pipe culverts,corrugated HDPE pipe culverts and other types of flexible pipe culverts have the advantages of lower cost,faster construction,more reliable quality,lighter weight and better durability,and the stress distribution is also more reasonable.Since there are many uncertain factors in theory and technology in the design and application of flexible pipe culverts,the research and application of flexible pipe culverts at home and abroad are still in the exploratory stage,and the contrastive study on soil-structure interaction law of different types of flexible pipe culverts has not been carried out.In this paper,the method of combining field test,theoretical analysis and numerical simulation is used to study the soil-structure interaction characteristics and mechanical properties of flexible pipe culverts.The main research contents and conclusions are as follows:(1)Based on the material characteristics of corrugated steel pipes and HDPE corrugated pipes,and combined with the results of field covering soil model test,the mechanical characteristics of different types of flexible pipe culverts are compared and studied.Both types of flexible pipe culverts show the deformation rule of "upward arching and then bend down" during the construction process.The flexible pipe culvert tends to be in the ring pressure state under the load,and the most unfavorable stress state of the structure may occur during the construction process.Compared with corrugated steel pipes,HDPE corrugated pipes are more flexible,and the pipe culverts with larger flexibility tend to spread the load to the soil on the pipe side.(2)Combining the characteristics of soil-structure interaction of flexible pipe culverts and related calculation theories,the key factors affecting the mechanical performance of flexible pipe culverts are analyzed.The soil arch effect redistributes the earth pressure around flexible pipe culverts.The necessary condition for the formation of a favorable soil arch above the pipe culvert is that the settlement of the inner soil column above the pipe top is greater than that of the outer soil column on both sides of the pipe top,resulting in a negative settlement difference.When the load conditions are the same,the relative rigidity of the pipe and soil is the main factor affecting the earth pressure and deformation of the flexible pipe culvert.(3)The finite element model considering the construction process of flexible pipe culverts is established by ABAQUS.The simulation results are compared with the test results to verify the validity of the model.Through the parameter analysis,the influence of the relative rigidity of the pipe and soil on the mechanical performance of flexible pipe culverts is studied.The deformation,vertical earth pressure and stress of the flexible pipes decrease with the increase of the compactness of the backfill.On the premise of ensuring the compactness and the thickness of the cover soil,the flexible pipe culvert is mainly subject to the ring pressure,and the deformation is no longer the main constraint of the bearing capacity.The pipe diameter has a great influence on the ring stiffness of the flexible pipe.For the flexible pipe with a larger diameter,it is necessary to increase the stiffness of the flexible pipe by increasing the wave height or wall thickness.When the thickness of the cover soil is the same,the bearing capacity of flexible pipe culverts with different ring stiffness differs greatly.Too large or too small ring stiffnesses may cause greater stress in the structure.(4)According to the characteristics of soil-structure interaction and the law of mechanical performance of flexible pipe culverts,the optimization design of flexible pipe culverts is considered from the aspects of the selection of flexible pipe stiffness and backfilling construction,and the selection method of flexible pipe stiffness and construction attention are proposed matter. |
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