Comparative Analysis On The Pipe-pile Composite Foundation Load-bearing Characteristics Of Variable And Uniform Section

The thesis is supported by “Study on single pile bearing capabilityand connection key technology of steps section concrete precast pipepile”program,which is founded by National Natural Science Founding.The deficiencies in the practice have been discovered by systematicalanalysis on composite foundation of traditional uniform section pipe pile.Work properties of ladder-shaped variable cross-section and uniformsection pipe pile in composite foundation have been contrast study byindoor model test and numerical simulation. The advantages of theladder-shaped variable cross-section pipe pile in composite foundation issummarized. The main research content has been drawn as follows.(1)On the basis of indoor large scale model static load test oncomposite foundation, work properties of ladder-shaped variablecross-section and uniform section pipe pile in composite foundation havebeen contrast study. Conclusions have been draw as follows: the stiffnessof ladder-shaped variable cross-section single pile is significantly greaterthan that of uniform section single pile; the pile-soil stress ratio and pileside friction of ladder-shaped variable cross-section pipe pile incomposite foundation is greater than that of uniform section pipe pile incomposite foundation; under same loading, the sedimentation and the pileend resistance of ladder-shaped variable cross-section pipe pile incomposite foundation is obviously less than that of uniform section pipepile in composite foundation. Therefore, composite foundationtechnology of ladder-shaped variable cross-section pipe pile has adopted,which makes the most of shallow soil to improve load transfer behaviorof single pile and bearing capacity of composite foundation, thesedimentation reduction of composite foundation has been preferablyaffected.(2)The ladder-shaped variable cross-section pipe pile in compositefoundation numerical modeling has been set up by the FLAC3D, thecorrectness and rationality of the numerical simulation model are verifiedby static load test results on composite foundation of indoor large scale model, which laid the theoretical foundation all-round analysis of theladder-shaped variable cross-section pipe pile in composite foundationand the subsidence characters.