Study On Long-term Performance And Durability Of Buried Corrugated Steel Pipe Culverts

The buried corrugated steel pipe culvert has been rapidly promoted and applied in China for its advantages of convenient construction,environmental protection,and many research work have also been done.However,there are relatively fewer studies on the long-term performance and durability of such structures.With the increase in the service period of buried corrugated steel pipe culvert,it is necessary to study its long-term stress performance and durability in order to ensure the safety of road traffic.In this paper,two buried corrugated steel pipe culverts with circular and pipe-arch section have been introduced.An experimental study has been conducted to evaluate the mechanical properties of the two culverts during the construction backfill stage and during operation.The mechanical characteristics and the evolution of the soil-structure interaction of the culverts have been compared and analyzed.Furthermore,a three-dimensional finite element model was established to simulate the impacts of construction backfill process and the effect of long-term consolidation settlement of the foundation on the mechanical characteristics of the two pipe culverts.And then a on-site buried test and a salt spray accelerated corrosion test is performed to predict the anticorrosion life of the corrugated steel pipe culvert located in saline soil region.Moreover,a corrosion protection design is proposed.The main conclusions are as follows:(1)The variation trend of the two corrugated steel pipe culverts with circular or pipe-arch section is basically the same during the construction backfill process,presenting the tendency of first arching and then gradually flexing downwards due to the soil compaction effect.This soil-structure interaction facilitates the culvert to bear larger amount of upper soil and driving loads,which is beneficial to the long-term service of the culvert.Due to a larger lateral rigidity of pipe-arch culvert,the displacement during the process of backfill process is smaller than circular section pipe culvert,while the horizental earth pressure is larger than circular section pipe culvert.(2)With the time passing,the vertical and horizontal soil pressure of the two pipe culverts gradually tend to be stable during operation,and the vertical soil pressure on the pipe top is less than the vertical soil pressure beside the pipes.Therefore,the positive soil-arching effect created by the upper soil has increased during operation so that the lateral soil is able to bear some load on pipe top,which is favorable to the pipe culvert.Circular section pipe has a better ability to adjust to deformation than pipe-arch culvert under settlement action.(3)A three-dimensional finite element model considering the lateral pressure coefficient to simulate the layered backfill process has been established on ABAQUS.It can be seen that the simulated results and the test results is basically consistent.It is proved that applying the balance method of ground stress considering the lateral pressure coefficient to the soil can effectively simulate the horizontal constraints generated by the soil in the construction process.(4)Through the treatment of field buried test and salt spray corrosion test data,a corrosive life prediction model for corrugated steel culverts was established based on the grey correlation analysis method.Furthermore,the corrosion resistance of the pipe culvert was predicted by using the estimated material service life method(EMSL),and it is predicted that the durability life of such structures in the saline soil area is more than 53 years.Then the corrosion resistance of different coating types was compared.And a design proposal of anti-corrosion in saline soil area is given.