Research On Deepening Design Of Large Diameter Pile Composite Foundation In Chengdu Area

In this paper,the construction of high-rise buildings in soft rock area in Chengdu as the engineering background,using theoretical analysis,numerical simulation and field test methods of large diameter plain bearing design method,characteristics and optimization of design parameters of replacing concrete pile composite foundation of deep research system.Firstly,this article through the finite element modeling,numerical simulation and analysis of the soft rock large diameter composite foundation,clearly showing the cushion of large diameter concrete replacement pile composite foundation deformation characteristics,deformation characteristics of large diameter pile and soil between piles and the deformation characteristics of pile-soil stress ratio and bearing mechanism.The bearing mechanism and bearing capacity of composite foundation on the theoretical calculation and the large diameter pile composite foundation by numerical simulation on the current specification of composite foundation on deep width correction,variable stiffness design,retaining pile design were discussed.The results show that with the increase of the raft area,the settlement of the raft gradually decreases,but the change is not obvious.Under the same conditions,the raft foundation is the center of the raft foundation edge more;with the increase of the depth of excavation,the settlement of the raft decreases with increasing depth,different excavation depth of foundation pit model,increase the bearing capacity.The standard value of bearing capacity of composite foundation with different depths is revised by the standard,and the results are safe.In order to eliminate the differential settlement of raft foundation,it is suggested that the stiffness of the composite foundation should be adjusted properly in the practical application of the project,so that the overall settlement of the raft is consistent.The most settlement can be used locally,appropriate adjustments to increase the length of pile or pile on the settlement of the appropriate encryption;the smaller part,consider appropriate adjustments to reduce the pile length(according to the experience of Chengdu,visible in the pile bearing layer of pile length in the range of 30%,not more than 3M),or part of the pile spacing increases,so that the differential settlement is reduced to a minimum.With the increase of pile length,the bearing capacity of composite foundation is slightly lower,but there is no obvious change.Finally,a large number of measured data are analyzed to verify the optimal design method and parameters are reasonable.It is proved that the application of the research results in the design of large diameter pile composite foundation in Chengdu area is safe and effective.