Test Research And Finite Element Analysis On The Bahavior Of Geogrid-reinforced And Pile-supported Composite Foundation

Geogrid-reinforced and pile-support 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.This dissertation has summarized the improvement of project application and research situation of geogrid-reinforced and pile-supported composite foundation, generalized the mechanism of action, theoretical calculation methods and design methods. And its behavior is studied by field experiment and finite element simulation technique.By field dead-load test of geogrid-reinforced and pile-support composite foundation, curves of settlement, pile stress, soil stress and geogrid tension force are got, then pile-soil ration and load sharing ratio are also got. The test shows: the settlement and differential settlement can be controlled effectively, and finished quickly; pile and soil stress and geogird tension force will enhance with load's enhancing, geogrid tension force will reduce with the enhancing of distance to pile, and the maximum of geogrid tension force appears the edge of pile. By cyclic loading and unloading test, the influence to geogrid-reinforced and pile-support composite foundation of cyclic loading is studied. The test shows, because of cyclic loading, settlement and differential settlement are increased, pile capacity are further displayed, pile-soil ration and geogrid tension force are increased.Using Plaxis7.2 finite element analysis software, the dissertation has made an analysis to the stability of geogrid-reinforced and pile-supported composite foundation, disclosures three kinds of destroy model, and studies the influence of geogrid floors, position and rigidity, pile characteristic and layer thickness to stability of geogrid-reinforced and pile-supported composite foundation.