Investigation On Interaction Between Geogrid And Xigeda Soil

Xigeda is a distinct soft rock distributed widely in Xichang and Panzhihua, Sichuan, P. R. C. Nearly one million cubic meters of Xigeda spoil are brought out in excavation in the building Xichang-Panzhihua speedway. It will make considerable economic benefits if the spoil can be utilized in the engineering. As we know, the geogrid placed in earth fill can enhance the strength of road embankments and reduce the settlement due to its high strength, low ductility. Moreover, its aging resistance is high.Currently, though geogrid has been widely applied in geotechnical engineering, the recognition to its mechanism is deficient. Especially, there is no precedent for the application of geogrid in Xigeda earth fill. The aim of this thesis is to research the mechanism of interaction between geogrid and Xigeda soil with laboratory test and numerical simulation and obtain the mechanical parameters to satisfy the demands in design and construction.In the thesis, firstly, the achievements concerning interaction of geogrid and soil are summarized and analyzed. An apparatus for direct shear and pull out test designed by the author is manufactured. With the equipment, five groups of direct shear test and four groups of pull out test are carried out and the strength parameters of the interface between geogrid and Xigeda soil including friction angle, cohesion are determined. Also, the influences of compactness, transverse rib of geogrid to shear strength of interface are analyzed.Furthermore, A finite element analysis to the process of pull out test is performed with ANSYS to recognize mechanism of the interaction betweengeogrid and the soil. Elasto-plastic model following Drucker-Prager law and elastic model are employed for the soil and geogrid respectively. Hexahedral element is adopted for both soil and geogrid. The interfaces between the soil and geogrid are simulated with contact element. Six geogrid with different location of transverse rib are calculated to analyze effects of rib. The computational results show good agreement with the test result. The rib can enhance the pull out capability of geogrid and its location has less effect on the pull out capability and more effects on the displacement of geogrid. The closer rib is near the pull out end, the less the end of geogrid displaces.