Tests Research On Engineering Properties Of Composite Foundations With CFG Piles

Because of short-range cycle of construction, reliable quality, and low cost, CFG technology has been widely applied in highrise foudation treatment of north area in last decade. But the combination of materials used in CFG piles and the factors which have effect on CFG piles engineering characteristic need a further research. This paper made a study of main parameters which affect the engineering characteristic of CFG piles on the basis of CFG piles machanical property experiment, field investigation and numerical simulation result analysis, and finally got following conclusion:1. Stone Chip rate plays an important role in the slump and strength of the Mixture. Best stone chips rate in this experiment is about 29%, stone chip rate is too small or too big could reduce the intensity of the mixture. Mechanical performance test indicate that later there is a large increase in intensity, despite the large number of fly-ash mixed with piles. The 90d strength of the mixture that with Fly-ash content in more than 40% have exceeded the design strength.2. Field experimental study indicative of despite the increasing strength of piles had leaded to enhance the bearing capacity of composite foundation, but it had less effect than pile length on engineering properties of the composite foundation with CFG piles. When the Pile length is 1.95m,the strength of three different pile composite foundation pile load settlement curve basically coincides.3. The results of numerical simulation show that as load plate size (base size) increases, vertical stress, pile-soil stress ratio and the settlement had increased, indicate that composite foundation with CFG piles have the same engineering properties with the natural foundation. The corrective action of cushion became clear when the thickness of cushion had been increased. With the increase in the thickness of cushion, pile-soil stress ratio had increased, the load which is assumed by soil is gradually increasing; However, the thickness of cushion is too large, it will increase the amount of foundation settlement.Figure [47] table [16] reference[51]...