Study On Bearing Capacity Behavior Of Geogrid Considering Brace Effect Of Rigid-flexible Piles

Rigid-flexible pile-supported composite foundation is a new type of foundation treatmentmethods, which is more economical. However, the study on reinforcement mechanism anddeformation characteristics of geogrid composite foundation is insufficient. Interfacecharacteristics between geogrid and soil by direct shear test and gergrid deformation behaviorconsidering brace effect of rigid-flexible piles by model test are stuied in this thesis.Combining with the actual working condition of composite foundation, direct shear testswith different soil materials in shear boxes were put forward. Effect of different factors oninterface characteristics between geogrid and soil were studied. The test results shows that theaffecting factors ranked in order of the biggest differences are vertical pressure, different geogridproperties, tensile strength of geogrid, particle size of cushion material and moisture content ofsoil. Based on the test results, shear strength model of interface characteristics between geogridand soil was proposed. Influence of geogrid on the interface characteristics between geogrid andsoil was also analyzed and discussed.The model tests were used to simulate deformation characteristics of geogrid consideringbrace effect of rigid-flexible piles. Based on the model test results, tensioned membrane effect ofgrogrid and soil arching effect in the geogrid cushion were analyzed. Deformation behavior ofgeogrid and the changes of pile-soil stress under static load were also analyzed. The results showthat grogrid located at the edge of piles is the easiest to fail. Tensioned membrane effect locatedat the edge of rigid piles is more obvious than that located at the edge of flexible piles. Variationof load frequency, load amplitude and load waveform only changes the responding curve ofgeogrid accordingly.This study is benefitial to the further understanding of interface characteristics betweengeogrid and soil in reinforced cushion, and to reinforcement mechanism and deformationcharacteristics of geogrid, which is reinforced in rigid-flexible pile-supported composite foundation.