Research And Application Of The New Mixing Soil-Cement Composite Pile On Retaining Structure Of Deep Foundation

SMW engineering method is a new method recent years,which has been used for soft soil area of retaining structure of deep foundation.This engineering method has been widely applied in Japan,in our country,Tianjin,Shanghai,Nanjing has already carried on the application,however,harder soil layer area likes Beijing not to be obtained the application .A improved method basis on SMW engineering was proposed,combined characters of the soil in Beijing ,which named the new mixing soil-cement composite pile.The mechanics characters of cement soil is summarized comprehensive in this paper.The strength theory and constitutive relation of cement soil as materials of deep excavation, are expatiated systematically。An embedded and systemic study of computing method of the new mixing soil-cement composite pile structure is carried in this paper。Based on pull-out testing results of H-shaped steel in the new soil-cement mixing composite pile, the pull-out law of H-shaped steel is obtained by comparing the ideal curve of pull-out force and displacement with that of testing results. A check computation is given to evaluate the recycle of H-shaped steel.Moreover,according to the practical construction situation of the new mixing soil-cement composite pile engineering method in subway station project of Beijing Olympic branch line,The FLAC3D software is used to analyze the excavation and the numerical predications.Some valuable conclusions were received, which supply reference to design theory and colculation means of the new cement-soil composite pile engineering methods.At present,the commonly subway construction method is the perfusion piles method retaining of deep excavation in the Beijing area, compared the perfusion pile with the new cement-soil composite pile carry on the economical contrast analysis and social efficiency analysis.