Application And Numerical Analysis Of Composite Pile Foundation In Bridge And Culvert Foundation Engineering

During the economic growth and urban construction, there had been rapid expansionin the infrastructure of transportation which has extremely improved the travel conditions forcitizens. Meanwhile, the problem of foundation design that how to reduce the waste ofengineering material and then save the cost of construction has been urgent. The composite pilefoundation has more advanced design idea and less construction cost, so it has been attractedmore concern from the geotechnical research workers and became a popular research field.Along with the improvement of composite pile foundation in design theory, the composite pilefoundation had been experimentally used in constructional engineering, and then it had beenwritten into the “Technical Code for Building Pile Foundations”（JGJ₉4-2008）. But in the existingcode of bridges foundation design, there still has explicit code that the upper loads need to becompletely borne by the piles without soil among piles. This code caused the wastes ofmaterials due to the bearing capacity of soil had been artificially ignored. This paper analysedthe feasibility of composite pile foundation design concept in foundation of bridges and culvertsfrom these parts below.A. On the basis of load transfer theory on single pile, this paper analysed the loadtransfer in piles and the load partitioning mechanism with piles and cap, confirmed theproperty of composite pile foundation under applied load. The preconditions of composite pilefoundation used in foundation of bridges and culverts had been acquired according to the analysison the relationship among each parts of composite pile foundation and the discussion on theinfluencing factor of load distribution.B. This paper analysed the design concept of composite pile foundation which were usedin project, compared various kinds of composite pile foundation design procedures with the piledesign concept in bridges and culverts foundation design code. The prerequisites of applyingcomposite pile foundation in bridges and culverts design were explicit, the computing method ofpile bearing capacity suitable for bridges and culverts foundation had also been worked out inthe basis of construction codes.C. This paper had made analysis on a bridge in forestry district and had affirmed that this district has the condition of composite pile foundation design. According to the comparisonon traditional pile design and composite pile foundation design, the superiority of composite pilefoundation in stock utilization was incarnate.D. In the last part of paper, the author had made finite element model on the projectabove by the FLAC3D software, affirmed the safety of composite pile foundation design inbridge foundation by the analysis and comparison on each critical data of design.According to the analysis of this paper, the author considered that the bridgefoundation can be certainly designed by the composite pile foundation design concept if thebridge has the conditions in this paper, and it will also be a new development direction offoundation design. The author expected to afford a number of theoretical or practical evidencefor the composite pile foundation which used in bridge design and developed the the compositepile foundation design concept.