Research On Particle Breakage Of Coarse Granular Soil Under Complex Stress Path

With the development of dam construction technology,the earth rockfill dam is getting higher and higher.The problem followed is particle breakage in the dam body under high stress.In addition,coarse granular soil,as the main filling material of earth rockfill dam,also is very fragile.Thus,particle breakage generated in the dam is considerable.Particle breakage can not only affect the strength,but also the settlement and deformation of the dam,and further the safety of the dam.Therefore,the problem of particle breakage cannot be ignored and is of much significance to study and analyze.In fact,particle breakage happens both in dam construction stage and in impounding stage.It is suggested that in dam construction stage,the internal stress development of the dam is close to constant stress ratio path,while in the impounding stage,the stress development turns to complex stress path.So it is necessary to make the loading process to specimen similar to the actual stress path when designing test schemes.Therefore,in this paper constant stress ratio path tests and complex stress path tests are conducted using large scale triaxial apparatus to simulate the construction stage and impounding stage of the dam respectively,and besides the rubber membrane penetration problem is explored through the isotropic consolidation test and the shear stress formula is amended as well.In this paper,firstly,the stress-strain relationship and the strain-volume change relationship of each stress path test are analyzed,and the characteristics of the constant stress ratio switching to1? unchanged with3? reduced path are highlightedly analyzed and explained.Secondly,according to particle size distribution curves of each stress path test and the content of each particle group,the particle breakage characteristics of each stress path are analyzed,and the relative breakage of each stress path is achieved.Finally,the hyperbolic form and the incremental hyperbolic form can be adopted to describe the relationship between the relative breakage and shear strain of constant stress ratio tests and complex stress path tests respectively,and then the relative breakage formulas and the relationship between the fitting parameters and stress ratio can be obtained.