STATIC CHARACTERISTICS TEST ON COMPOSITE FOUNDATION OF DIFFERENT TYPED-PILES ON AN IDENTICAL SITE

The site load and deformation tests for the composite foundation of different type of piles, including gravel piles, CFG piles, CFG-long piles and soil-cement-short piles and soil-cement piles with CFG core, are made on an identical site. The test results show that under an equal pile radius and an equal pile space, the load-settlement curves of the composite foundations of CFG-long piles and soil-cement-short piles and soil-cement piles with CFG core are a linear relation, and it is a non-linear relation for the composite foundation of gravel piles. The single-type-pile composite foundation bearing capacity is higher than that of a two-type-pile composite foundation. The bearing capacity of gravel piles, CFG piles, CFG-long piles and soil-cement-short piles and soil-cement piles with CFG core is respectively 210kPa, 225kPa, 197kPa and 182kPa. The stress ratio of a CFG pile to soil body among piles in the composite foundation of soil-cement piles with CFG core is the lowest, that of the composite foundation of CFG piles is the next lowest, and that of the composite foundation of CFG-long piles and soil-cement-short piles is the greatest. From the point of the stress distribution, the stress in the composite foundation of soil-cement piles with CFG core is the most uniform among the others. The arranged pile deep-layer form has a considerable effect on the deformation of composite foundations.