Experimental Study On Mechanical Characteristics Of Saturated Sand Under The Rotation Of The Principal Stress

The roadbed not only bears the static load such as the embankment dead weight,but also bears the long-term cyclic effects of traffic loading in the road engineering.All of these loads can cause the rotation of the soil unit principal stress,which will lead to greater cumulative deformation and strength reduction of the soil,even leading to a series of diseases and huge property losses.Therefore,it is of great value and significance to carry out the experimental study on the static and dynamic characteristics of soil under the rotation of the principal stress axis and make it as the engineering design guide.This article selects the saturated sand as the test object,chooses the combined sampling and saturation method of boiling water saturation,wet tamping method and back pressure saturation,a series of tests considering the rotation of the principal stress axis are carried out by using the hollow cylinder apparatus.The main contents are as follows:(1)The excavation or upper loading change may cause the initial principal stress angle changed from 0° to 90°of the different parts.A series of directed shear tests under different principal stress angle are carried out,research and analysis the effort of the principal stress angle on the deformation and strength of soil.(2)The difference of geological and stress history in the formation process of subgrade soil may cause the different consolidation state,the shear tests under different consolidation ratios are carried out,research and analysis the influence of the principal stress angle under the on the different consolidation ratios deformation and strength of soil.(3)The pure principal stress axis rotation may influence the static characteristics of the soil,the experimental study on the pure principal stress rotation under different partial stress ratio is carried out by using the hollow cylinder apparatus,the development law of axial strain,torsional strain and volumetric strain of soil were studied.(4)The traffic loading may cause the principal stress constantly rotation during the road operation period,The heart-shaped stress path caused by traffic loading is simulated by the hollow cylinder apparatus,and compared with the conventional dynamic triaxial test,analyze the influence of the continuous rotation of principal stress under traffic loading on the vertical deformation and modulus of resilience of soil.