FEM analysis and design of long-short-pile composite foundation

A practical case of the long short pile composite foundation is presented,in which the long and short piles are made of reinforced concrete and cement soil respectively.The stress distribution and displacement of the long short pile composite foundation、whole long pile composite foundation、whole short pile composite foundation and nature foundation under the same geological condition have been calculated and compared by FEM. The results show that by use of the long short pile composite foundation, the whole settlement is reduced effectively and the settlement difference of foundation slab is cut down. Long pile makes shallow soil stress reducing and deeper soil displacement falling. A design method of the long short pile composite foundation is introduced. After comparing the calculated value of the settlement with the actual measurement , it is proved that the design method is available.