Abstract：The paper describes a numerical model that is developed to simulate and analyze the response of three instrumented，full-scale，reinforced and un-reinforced slopes under a strip footing. The fast Lagrangian analysis of continua(FLAC) program based on strength reduction technique is used in numerical analysis. The displacement response，velocity vectors of nodal displacements，plasticity indicators and shear strain rate under strip footing are calculated. So the ultimate bearing capacities and the failure mechanism of two-part wedge for slopes are gained，which are in better agreement with test results. It is shown that the model is satisfactory. On the basis of these，the main factors influencing on slope stability are analyzed. Numerical results indicate：the bearing capacity and stability of reinforced slopes are obviously improved，and increase along with the add of the numbers of layers，stiffness and strength of geogrids. The larger the magnitude of strip footing is，or the farther away from the crest of slopes，the lower the stability of slopes is. The greater the soil strength is，the higher the stability of slopes is；but the friction of soils is more sensitive to safety factor than cohesion of soils. Besides，the depth of topmost geogrid to the width of strip footing is also greatly correlative to the safety factor，and the best ratio changes with the layers of geogrids.
