Tests On The Vertical Bearing Characteristics Of Pipe Steel Concrete Composite Pile

With highway extending to the ocean and river, more and more bridges that across the sea and river will gradually be constructed. Its foundation is most the pile foundation, and it is often through decentralizating steel casings to stabilize the pile hole wall in construction. Because of the needs of construction and casing depths greater, steel casing is no longer recovered. The engineering properties of steel casing is better than reinforced concrete, therefore, the mechanical properties of steel concrete composite piles is better than reinforced concrete piles. In the same conditions, the pipe steel concrete composite pile is better than steel concrete pile in the bearing capacity, obviously, economic and social benefit is not good. Actually, it is considered that the steel casings is used as safety factor in design.In this paper, combined with the bridge pile foundation entity project of Guangzhongjiang highway, based on investigation, the vertical bearing characteristics of pipe steel concrete composite pile is research through the centrifugal model test and numerical simulation. The main conclusions are as follows:1. Vertical ultimate bearing capacity of the pipe steel concrete composite pile is higher than that of the reinforced concrete pile, but it is not very large. And Steel pipe- reinforced concrete composite pile foundation is defined as pipe steel concrete composite pile when the pipe depth more than 12cm(12m in prototype).2. The squeezing effect sinking of steel pipe can produce compaction effect to the surrounding soil, and the contacting properties of pile and soil are improved, and the friction of steel segment side is promoted. When pipe depth is less than 12cm(12m in prototype), the double peaks of friction curve is appeared; When the pipe depth is more than 12cm(12m in prototype), the double peaks of friction curve is disappeared.3. The vertical bearing characteristics of pipe steel concrete composite pile is shown through three-dimensional numerical simulation once again. While the law in pile length and pile diameter is also shown. So the insufficient of centrifuge model tests is made up.4. Based on centrifuge model test results, the calculation formula of vertical bearing capacity of pipe steel concrete composite pile is get.