Static loading tests on long-short CFG-PHC pile integrated composite foundation

On-site static loading tests are carried out on three groups of long-short two-type-pile integrated composite foundations,so as to investigate the single pile working mechanism,the stress ratio between pile and soil,the share of load carrying and so on.It is found that the stress ratio and loading share of long pile are larger than those of short pile.When reaches the characteristic value of composite foundation bearing capacity,the share of soil exerts the larges,then the long pile,and the short pile.Beyond the load bearing capacity,the stress ratio between long pile and short pile tends to a steady value.The working degree combination method is suggested,and working degree of long piles and short piles are 0.6～0.8 and 0.2～0.3 respectively.The working degree of soil between piles may be more than 1,and 1.4～1.8 is suggested.