| In recent years,the technology of composite foundation has been widely applied and developed,especially the rigid pile composite foundation,pile and soil deformation in the coordinated action of cushion,which can effectively enhance bearing capacity of body can fully exert the bearing capacity of soil between piles.According to the formation characteristics of soft rock sites in Chengdu area,China Southwest Geotechnical Investigation&Design Institute proposed the concept and design method of large-diameter concrete pile composite foundation,in Baishi Mansion,"ICON cloud",Tazishan Yihao has good effect.But research on the deep theory of the characteristics of the bearing and the bearing mechanism is relatively small,and the basic design theory of soft rock sites,especially the theory of composite foundation are not unified and even vague understanding,such as the difference between large diameter concrete pile composite foundation,pile foundation and composite pile foundation bearing capacity and deformation mechanism,design the calculation method of composite foundation,the use of friction end bearing mechanism of reinforced composite body,etc.This paper combines the characteristics of the site of soft rocks in Chengdu area based on the measured results collected works and theoretical analysis,analysis of the use of the prototype monitoring results,finite element analysis method,comparative difference theory of composite foundation,pile foundation and composite pile foundation engineering characteristics,to analyze and discuss the stress and deformation characteristics and influencing factors of large the diameter of plain concrete pile composite foundation,the main contents are as follows:(1)Based on the pile foundation,composite foundation and composite pile foundation,the concept of force bearing characteristics and the basic design theory of comparative analysis,summed up the relationship between the three basic types,and discussed the selection principle of composite foundation and composite pile foundation.(2)The prototype monitoring is based on the experiment,combined with the data of geological prospecting and design calculation,the change law of large diameter concrete pile axial force,pile side friction distribution,pile-soil stress ratio of composite foundation,analysis in the whole process of bearing enhanced negative frictional resistance,the upper part of the pile body in a certain range of pile the axial force and pile top and pile soil stress and pile soil stress ratio increases with load variation.(3)The finite element analysis software ABAQUS is used to simulate and analyze the large-diameter plain concrete pile composite foundation and composite pile foundation.Comparison of the results calculated by the monitoring results and numerical simulation,verify the rationality of the model and the calculation precision and applicability of engineering needs;discusses the large diameter concrete pile in the upper load settlement and pile-soil stress ratio changes,analysis of influence of cushion,pile raft foundation and pile bottom soil etc.the stress and deformation characteristics of composite foundation,the range of parameters is obtained more reasonable.(4)By using ABAQUS finite element software,and compression of pile and pile end soil settlement and deep foundation of influence scope,the pile-soil stress ratio changes on composite pile foundation under the load of raft settlement,and the results were compared with the simulation of composite foundation,further deepen the understanding of composite pile foundation and composite the bearing mechanism of difference. |
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