Engineering Properties Of Loess Filler And The Numerical Analysis Of Embankment Slopes Reinforced With Geogrids

The embankments of roads in loess area are in all kinds of natural factors, especially under loads and rain, easy to produce a variety of diseases. So far, the stability of loess embankment still not had been resolved very well. Embankment stability contains two aspects of deformation and slope stability. The main factor that affecting embankment stability can be summarized as follows: the engineering properties of filler, compacting effects, the types of slop, the height of slop and the gradient of slop.Lay geogrids horizontally in backfilled soil of embankment is a new geo-technology. In recent decades, it developed quite rapidly. Geogrids can be widely used in various fields, such as highway, railway, architectural engineering, hydraulic engineering and so on. But in nowadays, the application of geogrids is limited greatly because of people have not understand the interaction mechanism totally between filler and geogrids.On the above issue, the main subject of this thesis is as follows:(a)Two types of loess in Yongdeng,Gansu province are selected to research the engineering properities of loess as embankment filler by laboratory geotechnical tests, such as compaction test, permeability test, compression test and so on;(b)With the study of plenty of interrelated references,in this thesis, the mechanism of settlement for embankment and the cause of uneven settlement for embankment of loess are summarized; the classification, engineering properities and the actuality and developing level of geogrids are introducted ; the research status of reinforced soil and reinforced embankment are reviewed;(c)Two types of potential destruction of embankment are simulated by calculation software of FLAC3D (Fast Lagrangian Analysis of Continua): the shallow collapse of embankment slope and the deep layer destruction of embankment slope. The safety factor of stability and the distribution of plastic zone of slope can be calculated by Shear Strength Reduction that embedded within the calculation software. The reinforcement effects in multi engineering conditions are discussed in this thesis;(d)During the construction, embankment is filled step by step rather than completed by one time. The trend that the stress and deformation is changing with the filling process can be reflected in this thesis;(e)Reinforced function of geogrid are mainly played by its tensile stress. The stress state of geogrids which have different positions and lengths are analyzed, thus guidance in the design and construction of reinforced embankment can be supplied and both the reinforcement effect and the economic interests can best satisfied.