Analysis Of Backfilling Construction Influence On Mechanical Behavior Of Buried Corrugated Steel Pipe Culverts

The buried corrugated steel pipe culvert has obvious advantages such as low construction cost,strong adaptability to deformation,convenient transportation,short construction period and environmental protection.Research and practical application investigations show that the worst condition of the structure is in the process of backfilling,not after the whole construction.Because of the difference in construction methods and process,it is easy to result in excessive structural deformation or even damage.At present,there are few domestic studies related on the influence of construction process on the structure,and lack of reasonable analytical calculation method.Therefore,it is necessary to analyze the influence of construction process on the mechanical performance of corrugated steel culvert.The main contents of this paper are as follows:(1)The finite element numerical simulation model with the consideration of construction process is established.Meanwhile,the deformation and stress of buried steel corrugated pipe culvert with different material parameters,constitutive models and lateral pressure coefficients during backfilling construction are discussed.Based on the aforementioned research,different compaction and the asymmetric backfilling construction method are analyzed.Results show that the improved constitutive model combined with Duncan/Selig nonlinear elastic model and Mohr-Coulomb elastic-plastic model can correctly reflect the stress of steel corrugated pipe culvert in the construction process,and with the increase of lateral pressure coefficient,the influence of soil-structure interaction on pipe culvert increases.Compaction have great influence on the deformation of pipe culvert and the top soil of pipe in the backfill construction process,and the stress of culvert top backfilling stage.The compaction should be greater than 95%.When the steel corrugated culvert is backfilled to the top of the culvert,the deformation and stress caused by asymmetric backfilling are the largest,and the culvert is the worst stress state.The symmetric backfilling should be strictly controlled to avoid damage to the structure.(2)In-site tests were carried out on the backfilling construction process of buried corrugated steel pipe culverts in Guangxi province,and the measured results were compared with the numerical simulation results.The results show that the backfill compaction and asymmetric construction have great influence on the mechanical performance of the structure,and the results of finite element calculation are in agreement with the measured results.It shows that the finite element modeling method established in this paper is suitable for the actual engineering situation.(3)A comparative test was carried out between rubber concrete and traditional backfill soil filled in wedge-shaped part of pipe culvert.The influence of wedge-shaped part filling on the construction process of pipe culvert is studied using finite element model for numerical simulation and parameter analysis.The results show that using rubber concrete in wedge-shaped part can improve the deformation and stress of structure in backfilling process compared with traditional backfill soil,and rubber concrete is more conducive to the deformation and stress of culvert than ordinary concrete,the greater the rubber content,the more obvious the advantages.And the suitable filling range should be determined by technical and economic analysis.