Theory Analysis And Model Test Research Of Geogrid-reinforced And Pile-supported Composite Foundation

This paper has reviewed the development of engineering application and research situation of geogrid-reinforced and pile-supported composite foundation, and summarized the correlative theory and design methods in the available literature, and then analyzed the mechanism of load transfer in theory, lastly investigated the working characteristics of composite foundation by model tests.Basing on discussing the force and distortion of the geogrid, three hypotheses were brought forward, and the distortion equation and the tension calculation method of geogrid have been derived. And basing on considering the effect of the height of same settlement plane, this paper also generalized and optimized the Terzaghi's calculation of arching in soil, pointed out the applicable conditions and advanced the modified methods.By thirteen model tests of geogrid-reinforced and pile-supported composite foundation, divided into six series, the effect of fills stuff, fills thickness, space between piles, material and size of piles, and reinforced floors on the behaviors of composite foundation, such as the settlement, the stress of pile and soil, the strain of piles and geogrid, has been studied. The test results shows that: bigger size of fills grain, more geogrid reinforced floors, bigger size of pile caps, and thicker fills will have larger stress ratio of pile to soil, which is propitious to the load transferred from soil to piles.