Study On Bearing Behavior And Calculation Method Of Bearing Capacity Of Combined-pile Composite Foundation

With the rapidly development of economy of our country, and the scale of construction extends continuously, the technique of ground treatment formed a set of more perfect theories system in long-term of engineering practice and theories study, the form of composite foundation also took place the bigger variety simultaneously. While satisfy the precondition of the safety, for economizing the funds better, in recent years, combined-pile composite foundation got the application in many actual engineering. At present this type of the composite foundation still is placed in the stage of experimenting and studying, and its theory is not further than the practice. For Studying on bearing behavior and calculation method of bearing capacity of combined-pile composite foundation, make the theories system of combined-pile composite foundation further perfect, and make it guide the engineering practice better, this paper includes following several aspects work:(1) Expatiate on the basic concept of the composite foundation, based on the original classification of the composite foundation, according to the reinforcing mechanism and design principle, to reclassify the composite foundation, according to the different engineering geology condition, the design project of the composite foundation was given. The research production of bearing behavior and calculation method of bearing capacity of combined-pile composite foundation is generalized.(2) Make use of the FLAC^3D program which based on the explicit finite difference method, rigidity (CFG pile) — granular (GC pile) combined composite foundation is simulated, adopt mode that load step by step in the process of bringing load to bear on the model so that make the process more near to actual engineering. Consider the change that include different loads, different thickness of cushion, and different modulus of cushion and different lengths of pile, educe the variety regulation of stress of pile, the pile-soil stress ratio and sharing of load, the conclusion is significative to the optimizing design of practice.(3) Based on enough study on the existing calculation methods of bearing capacity of combined-pile composite foundation , consider the working behavior of loaded combined-pile composite foundation and the general influence of different construction methods to the bearing capacity of soil, four coefficients, master pile bearing capacity exertion coefficient and minor pile bearing capacity exertion coefficient and soil bearing capacity exertion coefficient and soil bearing capacity improvement coefficient, were introduced. The calculation method of bearing capacity of multi-type-pile composite foundation was revised. A case show that computed results were in agreement with experimental date by loading test, the design theories of combined-pile compositefoundation was perfected by this method, it can be used in actual engineering of combined-pile composite foundation.