Deformation And Stability Analysis Of Reinforced High Embankment In The Loess Region

The high-embankment is a commonly form of structure in highway construction when a highway crosses a gully in the loess region. However, the structure obviously shows some problems such as a large volume of fill, more space taken and other shortcomings. The high-reinforced embankment technique presented in this study provides effective approaches to solve the above problems caused by the high embankment.According to the results from investigation, exploration, test and monitoring in field as well as the triaxial test, lab modeling, both static & dynamic finite element methods and slope stability analysis carried out for the high-reinforced embankment, the study systematically explores the mechanism of reinforcement of geogrid, determines the deformation and stability and investigates the reasons for all possible failures of the high-reinforced embankment in the V-shape gully in the loess area.This study researched engineering geological conditions of the high-reinforced embankment and analyzed the feasibility of constructing high-reinforced embankment in Beizhang gully area.First, through the triaxial test on the samples of the reinforced soil, nonlinear parameters were obtained and the effects of different reinforcing methods for the reinforced soil on its stress, strain, and shear strength . Based on the above work, the nonlinear stress-strain relation curve of the reinforced soil was derived. On the basis of the actual field landform and topography, a simulation test was modeled using similarity theorem. This study embeds gauges in the in-situ geogrids at the construction site and to monitor the distribution of stress and distortion patterns during road construction.It has been the first time for the study to successfully adhere the plastic-strain gages on geogrid and find the rules of lateral stress increment of the high-reinforced embankment during construction. The relationship between lateral-strain (ue) and earth fill thickness (h) can be defined as:ue=aln(h)+b. Additionally, the subsidence mark, vertical and lateral stress boxes in different sites of the high-reinforced embankment were employed. The data from stress box indicate that the observed values usually are smaller than the theoretical ones, and the relationship between the vertical or lateral stress () and the fill soil thickness can be described in a power function curve: a- a hb. The fact that the soil stress is bigger in the portion adjacent to the central part of gully and becomes smaller in the portion close to the side illustrates that the gully has an apparent unburdening effect. From the monitoring results of the settlement deformation during and after constructingperiod, the study conducts statistical system analysis and evaluation on the change of settlement (S) with time (t). On the basis of the above work and the regress analysis (S=aln(t)+b), prediction and evaluation for the settlement deformation of the high-reinforced embankment after constructing have been made.With all the field and indoor test results, this study used finite element method (FEM) to simulate the stress and deformation of the un-reinforced and reinforced embankment under both gravity and earthquake conditions. Also, the method is adopted to simulate the earth fill load pressure above culvert and the deformation in reference to the earth fill thickness, angle of gully, width of gully, and whether reinforced or not during construction. Some engineering techniques for reduction of earth fill load pressure above culvert is provided by using FEM.Moreover, the study introduces the method using the principles of fuzzy information optimization(information diffusion, fuzzy approximate reasoning and information integration)to evaluate the stability ofthe high-reinforced embankment. A general information matrix of classification and evaluation indicators onthe high-reinforced embankment has been set up, and a test in using the matrix on the stability ofhigh-reinforced embankment of the Beizhang gully area has been tried by the study.Finally, the study o...