Experimental Study On The Performance Of Buried HDPE Corrugated Pipe Culverts

As a kind of flexible pipe with many advantages,HDPE corrugated pipes have been gradually used in highway over-water culverts.In order to expand the application and promotion of this type of pipe,in this paper,the effects of temperature change on the stress and deformation properties of different types of HDPE pipes are first studied by parallel plate loading experiments under different temperature conditions.The applicability of this kind of pipe under high temperature conditions is discussed.After that,in order to increase the span of HDPE corrugated pipe culvert and reduce the amount of backfill,buried experiments of HDPE corrugated pipes in double-layer arrangement are carried out,and the mechanical behaviors,deformation laws and soil-pipe interaction characteristics of the structure under standard and rapid construction conditions are studied.At the same time,it provides convenience for the emergency rescue project.Finally,the influence of temperature change on the mechanical properties of large diameter HDPE corrugated pipes and the load-carrying performance of large-diameter HDPE corrugated pipes in double-layer arrangement as well as the effect of the temperature change are discussed by the finite element software ABAQUS.Based on above researches,the following conclusions are obtained:(1)The mechanical properties of HDPE double-wall corrugated pipe are very sensitive to temperature change,however,the temperature change has little influence on the mechanical properties of steel-reinforced HDPE spiral corrugated pipes.As for 0.6mdiameter HDPE corrugated pipes,when the temperature increases from 0 °C to 30 °C,the bearing capacity when the vertical deformation rate is 2% and the ring stiffness of doublewall HDPE corrugated pipe decrease by more than 40%;while the bearing capacity and ring stiffness of steel-reinforced HDPE spiral corrugated pipe almost do not decrease on condition that the vertical deformation rate is below 10%.(2)The deformation characteristics of the bundled system consisting of doublelayer-arrangement HDPE corrugated pipes are basically the same under standard construction and rapid construction conditions.During the loading process,the deformation response of the pipe in the middle of the lower layer is the largest,followed by the pipes in the upper layer,the pipes on both sides of the lower layer are the smallest.With the gradual increase of equivalent soil cover thickness,the pipes on both sides of the lower layer become irregular elliptical shapes,the pipe in the middle of the lower layer gradually becomes a inverse horseshoe shape,the pipes in the upper layer gradually change into a horseshoe shape.(3)The backfill construction quality has a great influence on the bearing capacity of the bundled system consisting of double-layer-arrangement HDPE corrugated pipes.When the vertical deformation rate of the pipe in the middle of the lower layer is 3%,and the thickness of the covering soil is 0.7m,vehicle load with a rear axle weight of 45.8t can be borne under standard construction condition,and only a vehicle load with a rear axle weight of 12.3t can be borne when using the rapid construction method.Therefore,when adopting the rapid construction method,the thickness of the covering soil should be increased properly to reduce the influence of the live load.(4)During the loading process,the vertical earth pressure on the top surface of the bundled system and the horizontal earth pressure on the side are gradually increased.And in the process of increasing the uniform load on the top surface of the culvert,due to the increase of the soil density on the pipe side and the decrease of the overall stiffness of the bundled system,the soil-structure interaction of the culvert structure increases gradually.(5)It can be seen from the numerical simulation that the temperature change has certain influence on the mechanical properties of the large-diameter(1.0m and 1.5m)steel-reinforced HDPE spiral pipes and the bundled system formed by large-diameter HDPE pipes,but it is not significant;when the bundled system adopts the HDPE pipes with the same ring stiffness and larger diameter,no matter the standard construction method or the rapid construction method is adopted,the bearing capacity of the bundled system will improve with different degrees instead of reducing.