Experimental Study On Effect Factor Of Loess Subgrade Eformation

With the implement of West China Development Strategy, transportation and highway engineering, especially highway, which drives economic development of western region, has priority to development, also the road construction progresses rapidly in western loess area. With the appearance of a large number of road which used loess as subgrade fill, there are many deformation and failure of loess subgrade appeared in road construction of loess region. When the experience of road construction is accumulated constantly, human realize the importance of loess subgrade increasingly, and the deformation of loess subgrade which relates with whole stabilization and safe of road is one of important studies all the time. So it is necessary to study and analyze the law of loess subgrade's deformation for prevent loess subgrade from damage.The roadbed deformation is not only related to properties of filling material, but also related to traffic load. In actual project there are many disadvantage, for example the uneven of soil grain,the difficulty of controlling filling soil's water content,the nonuniform,insufficient of degree of compaction and also; because of the infiltration of surface gathered water and phreatic rise, the increase of water content lead to soaking deformation; traffic load makes roadbed form excessive permanent deformation and makes nonuniform subsidence.This problem will affect safe operation of road. Via compression test,collapsibility test,circulator compression test and dynamic torsional shear test, this paper analyze the impact of water content,degree of compaction and applied load on deformation of loess subgrade, finally draw some conclusions as follow.(1)The impact of water content of roadbed's soil on the coefficient of compressibility,the coefficient of collapsibility,cumulative deformation,permanent deformation,dynamic shear modulus of soils and damping ratio is rater distinct. So water content act a important role in subgrade's deformation, with increase of water content the deformation of loess roadbed increase.(2)The degree of compaction have some influence on deformation of loess, the higher the degree of compaction, the lower the compressive deformation,soaking deformation and vertical cumulative deformation. In dynamic torsional shear test, dynamic shear modulus and damping ratio have low sensitivity to degree of compaction, the variation laws with degree of compaction have no obvious regularity.(3)Applied load is a extrinsic factor resulted in subgrade's deformation, also one of the most important factor. By the action of load roadbed always have the problem of deformation. When other conditions are the same, the higher the applied load, the more the deformation; the longer the time of loading, the more the deformation. But under the condition of lateral confinement, the deformation finally tends to a stable value.