Study On Deformation Characteristic Of Large Spacing Deep Mixing Pile Composite Foundation

Cement soil mixing pile reinforcing foundation is a method which is often used in soft-soil foundation treatment. Because it has many excellence, such as no vibration, no noise, no pollution, it is widely used in the old city reconstruction .but it has some mistakes on the design .Theoretic research still lags( And designer is often afraid that it will make the composite foundation settlement larger when pile spacing is larger. So traditional design method , littler pile spacing design method ,is often used.The pile spacing is 0.8m - 1.2m and piles is set in all the cite according traditional design method when mixing pile composite foundation is designed. But it is seldom used when pile spacing is more than two time pile diameter. This paper had load-deformation relation research, discusses its working mechanism and designing method according one larger pile spacing composite foundation, detailed content is as follows:(1) Discusses some factors affecting mixing pile composite foundation deformation such as pile length, replacement ratio, pile deformation modulus, pile spacing;(2) Discusses mechanism which large pile spacing composite foundation forms "reinforced cushion" to diffuse additional stress among the "effective pile length"; points out large pile spacing composite foundation's settlement calculation method according double layer foundation theoretic;(3) In order to convenient for engineering applying, explains basic hypothesis - calculating formula and detailed computing steps of large pile spacing composite foundation settlement calculating,(4) Contacting detailed engineering example , compares between calculated and measured results of large pile spacing composite foundation; also computes out corrected coefficient of composite foundation settlement calculating method according calculated results of traditional composite foundation examples;(5) Perfects designing steps of large pile spacing composite foundation according above working; and discusses some questions of designing method according controlling deformation and of optimizing design method; also emphasizes it is important for insuring design quality of large pile spacing composite foundation to perfect constructing organize design and enhance technique-quality measures.