| Geogrid-reinforced and Pile-supported(GRPS)composite foundation, as an advanced technology of foundation treatment, has been widely used because of its good technical and economical benefit, such as controlling settlement and differential settlement.Firstly, the thesis introduced GRPS's development history, application in projects, mechanisms offload transfer, existing computational methods and unfathomed problems. Then, its behavior is studied by field dead-load test and cyclic loading and unloading test. Based on elastic theory and tensioned membrane theory and choose typical geosynthetic-pile-soil analytical cell, the testing process of the test is simulated With Plaxis 7.2 2D program.(1) By field dead-load test of geogrid-reinforced and pile-support composite foundation, settlement, pile stress, soil stress and geogrid tension force are got. We protract the curves and analyze. The test shows: Different settlement is occurred in the Geogrid-reinforced and Pile-support composite foundation, and soil's settlement is the most settlement of it. Pile and soil stress and geogird tension force will enhance with load's enhancing. When the load reachs 2000kN, geogird is put in a nicer work state. The maximum geogrid tension force appears the edge of pile, and the minimum geogrid tension force appears the bestraddle of pile.(2) Through loading and unloading experiment, the thesis has studied the effect of the composite foundation under cyclic loading. The test shows: because of cyclic loading, settlement and differential settlement are increased, pile-soil ration and geogrid tension force are increased.(3) With Plaxis 7.2 2D program, the locale test process is simulated and the results are contrasted with the results of the finite element analysis. Feasibility of the finite element analysis is validated by the results.
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