Study On Bearing Capacity Of Long-short-pile Composite Foundation And CAD

Recently, with the theoretical and technologic development of compositefoundation, many new types of composite foundation have been put into design andconstruction. The long-short -pile composite foundation is one of them. Long-short-pile composite foundation could make full use of intepile soil bearing capacity withthe displacement-coordination of pillow, reduce the quantity of piles, and satisfysettlement and bearing capacity requests.Firstly, the general developing situation and basic theory of composite foundationare summarized in this paper, and the use and research production in long-short-pilecomposite foundation is specially introduced.Secondly, based on the data in-situ test, the author analyzes bearing capacity andsettlement character of long-short-pile composite foundation, discusses the bearingcapacity about piles and interpile soil in long-short-pile foundation. The result of thein-situ test indicates that:With the load on the long-short-pile composite foundation, the pile-soil stressratio increases fast, but the long-short pile stress ratio increases adagio. The interpilesoil supports the load on composite foundation mostly. When the load on thelong-short composite foundation is equal to its characteristic value of bearing capacity,the load on the long-pile, short-pile, & interpile soil could not attain theircharacteristic value. In the in-situ test, the load on the long-pile and short-pile are lessthan their characteristic value, the load on the interpile soil is more than itscharacteristic value.The characteristic value of bearing capacity for natural foundation( f ak), & that for interpile soil ( f sk), and that for interpile soil in work state ( f s'k) aredifferent. In a general way, f s'k> f sk> f ak.Finally, based on the analyses of the test, the model and methods of bearingcapacity and settlement have been proposed, and the calculation programme with VBis designed, it is convenient to the practice.