The Theory And Engineering Application Of Composite Foundation

The theories and the applications of composite foundation are quite activethe research direction in civil engineering field at present. The nearly more thanten for years, the technology of composite foundation have obtained biggerdevelopment. Because the composites reinforced in composite foundation aredifferent, therefore, the load bearing mechanism of each kind of compositefoundation is not all the same.In this paper, the bearing characteristics, the design methods and theengineering applications of the gravel pile and the rigid pile compositefoundations are carried on systematic research.1. The development and the research present situation of compositefoundation are summarized and the extant main questions of compositefoundation are pointed.2. The ultimate bearing capacity, settlement calculation methods of theexisting Granular Columns composite foundation are carried on the summaryand the general design methods of the existing Granular Columns compositefoundation are discussed.3. Based on the massive projects practices of author, the comprehensiveproject appraisal methods about anti-liquefaction appraisals and bearing capacityappraisals of the gravel piles composite foundation are established. On the basisof Using Rayleigh wave velocity to evaluate liquefaction judgment of naturalground, comprehensive consider the effect of stress concentration and verticaldrains action of gravel piles. The liquefaction judgment methods of the gravelpiles composite foundation are given in the different earthquake resistance;based on the commonly used methods in project, such as dynamic sounding testand Rayleigh wave method, the methods that evaluate the pile body quality ofgravel piles are established. The engineering calculation methods about bearingcapacity, pile-soil stress ratio and deformation modulus of composite foundationare given, contrast with the conventional static load test method and the methodsof this paper completely satisfy the requirement of actual projects.4. The design principles and philosophies of rigid pile compositefoundation are discussed. The change rules of pile-soil stress ratio and pile -soilbearing load ratio are obtained through the field static loading test of CFG pilecomposite foundation. The mechanisms of cushion of rigid pile compositefoundation are analyzed and the cushion reasonable thicknesses in projects aresuggested.5. Single pile composite foundation numerical analysis model is establishedby utilizing general FLAC3D finite differential program, the soil around pilesmodule, soil under the pile module, cushion thickness, cushion module, pilelength, replacement ratio and pile body elastic modulo are influential tosettlement, soil under the pile settlement, compression of cushion and pile-soilstress ratio of the CFG foundation, these influences have been separately carriedon the research, has the instruction significance to the engineering design andthe construction of the composite foundation.6. Used the axial symmetry explanation of generalized the plane stressproblems, separately considered the lateral confinement of soil and cushion, thecalculation methods of cushion compression of pile top are deduced. AppliedBoussinesq's solution and the elastic theory solutions which are different moduloin tension and compression, supposed friction resistance along the pile anddisplacement of pile-soil are ideal elastic-plastic relations, a new revise thedifferent molds method that calculate the settlement of rigid pile compositefoundation is deduced, this method considers interaction of pile-soil-cushion.7. The multi-piles composite foundation load bearing character and actionmechanism of composite piled raft foundation have been carried on the analysis.8. The working performance under horizontal load and the seismic loadingof the rigid pile composite foundation are analyzed, the rigid pile compositefoundation has an excellent anti-seismic characteristics.