Experimental Study On Ratchet Effect Of Crushed Stone Based On C-M Yield Criterion

Landslide is a bad natural geological phenomenon,according to stratigraphic lithology can be divided into clay landslide,heap landslide,rock landslide,broken rock landslides,landslides and loess landslides.With the development of underground engineering,earth-rock dam engineering requires a lot of geological research and analysis.There are many studies on the gravel as the main material,but it is not completely involved in the study of the crushed earth and the improvement of the experimental stability by the convenient and reliable test method.In this study,the strength and deformation characteristics of the mixture of steel and gravel are used to evaluate and detect the characteristics of the same particle size gravel soil,and the mechanism of distinguishing the coarse particles from the motion and the mechanism of the interaction of the mixture.In this paper,the shear strength of crushed earth is measured by triaxial test,and the ratcheting effect and stability of the gravel soil during the test loading process and the service failure process are studied,that is,the various morphological forms of the particles,,Friction and rolling and other forms of movement.According to the data obtained from the test,the CM yield theory is used to draw the shear strength envelope and the shear strength parameters are obtained.The relationship between the principal stress difference and the axial strain curve,the molar circle and the fitted shear strength envelope,and the shear strength parameter in each experimental state can be obtained.Analysis of the behavior of coarse particles in the process of gravel soil load.Analysis this trial and the results of the analysis are as follows:(1)The main stress difference-axial strain curve of the mixture of gravel-soil mixture,including the mixture of steel-and-to-column soil,is divided into three stages,namely,elastic deformation stage,yield stage and strain hardening stage.Each curve of the elastic deformation phase is approximately linear.The curvature of the principal strain difference-axial strain curve in the yield phase tends to be consistent.Strain hardening stage showed hardening characteristics.Therefore,it can be used to compare and analyze the intergranular gravel soil with the mixture of steel and gravel to achieve the simplification test and replace the more complicated and discrete crushed earth test.(2)The main stress difference-axial strain curve of the steel-and-rock mixture is relatively smooth as a whole,and the coarse-grained steel ball is the point-to-point contact,and its movement is mainly sliding.These determine that there is no bite between the ball and the soil and rolling.However,the effect of the occlusal effect on the shear strength of the lithotripsy effect of the crushed stone is well analyzed by this test method.And the mixture of steel and gravel is relatively easy to control the test material and stable test data,the improvement of the interstitial grain gravel test stability.(3)Through the analysis of the triaxial test of the lithotripsy effect of crushed stone,it can be seen that the soil samples used in the reconstituted crushed earth test have no significant peak intensity under the confining pressure.The confining pressure determines the stress state and the motion form of the coarse particles in the gravel soil.Under high confining pressure,compared with the steel ball mixture,it is proved that the coarse rolling and mosaic of the coarse particles in the crushed stone soils determine the improvement of the shear strength of the gravel.(4)The shear strength of crushed soil is not only related to gravel content,but also to particle size and shear rate.In the high content of crushed earth,the smaller shear rate has an improved effect on the shear strength of crushed earth.The shear strength is improved at low shear rate,which is mainly due to the friction between the particles.At high shear rate,the soil particles play the role of lubrication,Small gravel particles in the slip movement and rolling.The mixture of steel or the like or the ideal coarse-grained mixture is used as the reference base for the evaluation of crushed earth,and the ball-soil mixture has similar force and motion.(5)Diameter steel ball in the same soil and gravel soil mixture,the elastic modulus of the soil particles and coarse large value.However,when the amount of stone is high,the cohesive force between the steel ball and the gravel particles and the soil particles is small.At the same time,when the stone content is low,the earth particles have a wrapping effect on the gravel particles and the steel balls.The process is not enough gravel particles broken,coarse particles did not damage,the sample compression has reached the destruction of the standard.Therefore,the elastic modulus in both cases is not the main factor affecting the test.