Numerical Simulation Analysis On Stability Of Turnup Geogrid Flexible Supporting Expansive Soil Slope

Since the geogrid flexible supporting structure was put forward in 2004, it is the most effective,economical and environmental technical measure for dealing with expansive soil cutting landslide. Butit’s the design theory, analysis calculation method, mechanism of the geogrid flexible supporting soils andso on need further research. Numerical simulation analysis on stability of turnup geogrid flexiblesupporting expansive soil slope is carried out by the paper combining with constructing practice of thegeogrid flexible supporting expansive soil solpe in the Nanning outer ring expressway.Firstly，selected the typical expansive soil samples in the Nanning outer ring expressway startingfrom the geographical and geological characteristics of road section. In order to get the elastic andstrength parameters, laboratory consolidated fast shear test, expansive force test and consolidation test onnatural state and saturation state were carried out.Secondly, based on comparability between thermal effect of temperature variation and expansioneffect of hygroscopic expansion, in order to get the expansion coefficient of hygroscopic expansion,according to equivalent between temperature field and humidity field, expansive force test was simulatedby thermal-mechanics coupling analysis in FLAC3D. According to the defect of strength reductionmethod in FLAC3D, increased analysis accuracy and shortened analysis computing time of slopestability analysis by improving in FISH.Subsequently, FLAC3D was used to simulate the excavating process step by step, for getting thestress and strain of slope and stability of slope by improved strength reduction method; in order to get thebest excavating slope ratio, slope height and slope ratio, the influence of cut slope stress and deformationand stability by slope ratio were discussed to get the relationship about stability coefficient, slope heightand slope ratio; the characteristics of stress and deformation of hygroscopic expansion and hygroscopicsoften in dry-wet cycle remarkable influence region by thermal-mechanics coupling analysis in FLAC3Dagain.Finally, according to structure characteristic of the geogrid flexible supporting structure whichturnup and link geogrid, fill and compacte expansive soil after layered paving geogrid form complete, theaccording with practical slope model of expansive soil was established by geogrid structural units inFLAC3D; analyzed the development rule of stress and deformation and generalized plastic strain in theturnup geogrid flexible supporting expansive soil slope after expansive soil was absorbed moisture indry-wet cycle remarkable influence region; according to compare with non treatment expansive soilslope and un-turnup geogrid flexible supporting expansive soil slope, and combine with thecharacteristics of stress and deformation of the geogrid in expansive soil slope, analyzed the scientific andrationality of the mechanism of“frame hoop”function for expansive soil cut slope can be dealed by the geogrid flexible supporting structure.