Centrifugal Model Tests Of Geogrids-Reinforced Xigeda Strata Highway Embankments

The Xigeda strata is widely distributed in Xichang and Panzhihua area of Sichuan Province. The strata has some special characteristics of to be mashed and extremely softened by water, breaking when dehydrated and so on. So these poor engineering characteristics should be carefully considered when choosing foundation soil for heavy buildings, bridges and hydraulic structures. And this kind of soft-rock has not been used for expressway construction yet.The Xipan Expressway is a major part of the Lanzhou of Gansu to Mohan Ports of Yunnan Expressway, which is one of the eight western accesses planed by Ministry of Communications of China. With incomplete statistic, there are nearly one minion steres of Xigeda strata need to be excavated along the way, though great efforts have been made to avoid from this soft-rock. So how to take use of Xigeda strata for freeway construction is an inevitable problem for the Xipan Expressway.Geogrids-reinforcement is a significative attempt to resolve this problem and this has already been applied in the design of several parts of the road. But the research works on geogrids are unsatisfying and there are many unsolved problems both in theory and practice. The application is based on experience and tentative. One basic problem is the mechanism of the interaction between the soil and polymer is unclear, neither the numerical model. For most applications, there is no analysis theory or credible design methods.This thesis is based on the project of "Research on the Geogrids-Reinforced Xigeda Strata Highway Embankments", a west communication construction project from Ministry of Communications. Six groups of centrifugal model tests have been done with three groups are geogrids-reinfored, three are not. The prototype is K49+760 ~ K49+820 of Xipan Expressway. We measured the settlements of the top of the model, the horizontal and the vertical earth pressure in the model, trying to find out the distribution rule of the deformation and earth pressure of the embankment under different conditions. We also try to find out the effect of the geogrids embedded in the embankment by contrasting the pressure transfer and deformation between the reinforced embankment and the unreiforced one. These works are foundations of the research on the mechanism of the...