Experimental Study On Shear Characteristics Of Red Sandstone Coarse-grained Soil Under Different Consolidation Conditions

Red sandstone coarse-grained soil is a product of red sandstone disintegrated by natural or artificial weathering.It is widely distributed around the world.Due to its characteristics of easy disintegration and weakening of strength in water,uneven settlement is prone to occur in the project.And diseases such as slope instability.In addition,the consolidation state of red sandstone coarse-grained soil in nature and engineering is different,resulting in a large difference in shear characteristics,and further research in this area is needed.Therefore,for the red sandstone coarse-grained soil in southern Jiangxi,a large-scale direct shear instrument was used to carry out the shear test of the red sandstone coarse-grained soil.The influence of soil shearing characteristics has obtained the corresponding influence law.The main research contents and results are as follows:(1)Through a series of physical and mechanical tests,some basic physical and mechanical indicators of red sandstone coarse-grained soil were measured,which provided a reference for subsequent test programs and parameter settings.(2)The Shear Trac III large-scale direct-shear test system was used to perform the consolidation drainage drainage test on the normally consolidated OCR = 1 red sandstone coarse-grained soil.The influence and mechanism of different shear rate,water content and vertical load to its shear deformation characteristics are discussed and analyzed.(3)For the over-consolidated red sandstone coarse-grained soil,indoor large-scale direct shear tests were conducted at the consolidation ratios of OCR = 2 and OCR = 3,respectively,and over-consolidated red under different shear rates,water contents,and vertical loads were obtained.The shear deformation law of sandstone coarse-grained soil is compared with the shear deformation of red sandstone coarse-grained soil under the condition of normal consolidation ratio OCR = 1,and the difference and internal mechanism of the shear deformation law are analyzed.(4)The influence and mechanism of overconsolidation ratio,shear rate,and water content on the peak shear strength and residual strength to red sandstone coarse-grained soil are compared and analyzed;and the shear strength indexes under different test conditions are obtained by using Mohr Coulomb theory and the function of EXCEL program solution,and the effects of different overconsolidation conditions,water content and shear rate to the cohesion с and internal friction angle ? of red sandstone coarse-grained soil are compared and analyzed.The relevant parameters and fitting formula of the model are obtained by using the quadratic term model.