条形荷载作用下加筋土边坡稳定性分析

STABILITY ANALYSIS OF REINFORCED SLOPE LOADED BY A STRIP FOOTING

建立了用于模拟和分析3个大型室内足尺加筋与不加筋边坡稳定性的数值计算模型。数值计算采用基于强度折减技术的连续介质快速拉格朗日分析方法,分别对条形荷载下的位移响应、节点位移速度向量、塑性区和剪应变速率分布进行计算,获得3个边坡在条形荷载下的极限承载力和双楔体破坏机制,计算结果与试验结果吻合较好,验证了模型的可行性。在此基础上,对影响边坡稳定性的各主要因素进行分析。研究结果表明,经过格栅加固的边坡承载能力和稳定性明显提高,且随加筋层数、格栅刚度和强度的增加而增大;条形荷载越大或荷载位置离坡顶越近,边坡的稳定性越低;土体强度增大,边坡的稳定性明显增加,但土体摩擦角对安全系数的影响比黏聚力更为敏感;此外,顶层筋材埋深与条基荷载宽度比值大小与边坡的安全性密切相关,其最佳比值随加筋层数不同而改变。

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.