Study On The Soilbag Reinforced Sandy Subgrade Under Dynamic Loading

At present,with the acceleration of modernization in China,there are a large number of areas with adverse geological conditions need to be strengthened and reformed to meet the requirements of engineering construction.Due to the advantages of relatively low cost,convenient transportation and extensive use,geosynthetics have attracted more and more attention.Soilbag is one of many geosynthetics,made by putting soil into a woven bag,which is used to construct temporary structures.In recent years,some scholars have found that soilbag can play the effect of reinforcement,vibration reduction,protection from frost heave and so on.Therefore,this paper mainly studies the application of soilbag in strengthening subgrade,and proposes a new type of soilbag with internal belts reinforcement,which has better reinforcement effect than conventional soilbag proved through laboratory model test under cyclic loading.Specific research content and results are as follows:(1)The ultimate bearing capacity formula of the system is derived by analytical method.It is found that the ultimate bearing capacity is directly related to the thickness of the soilbag material,the internal friction angle of the filling material,the friction coefficient between soilbags and the boundary shape of the soilbag.(2)The corresponding stress-strain relationship of a new belt-confined soilbag under cyclic loading is studied,and it was embedded in the sandy subgrade as a kind of reinforcement method.The results show,compared with other experimental groups,the settlement of new type of soilbag reinforced subgrade is minimum and the resilient modulus of the subgrade is highest.(3)In the dynamic loading test of calcareous sand subgrade reinforced by soilbags made of different materials,the dynamic response of surface settlement,internal soil pressure and acceleration of subgrade are systematically studied by setting load amplitude and excitation frequency as independent variables.Soilbags can effectively improve the bearing capacity of calcareous sand subgrade,and the reinforced efficiency of soilbags made of polypropylene woven material with expandable polyethylene composite material is the highest.