Experimental Study On Strength And Creep Characteristics Of Strongly Weathered Argillaceous Sandstone

Strong to fully weathered rock formations are secondary weak layers,with low mechanical strength,poor engineering properties,and rheological properties.If such rock formations are encountered in slope treatment or tunnel construction,it is easy to cause strength degradation which affects the overall stability.In this paper,the strong weathered argillaceous sandstone of Huaiba Landslide in Mianchi County,Henan Province is taken as the research object.Through large-scale triaxial shear and creep tests,the strength and creep characteristics of strongly weathered argillaceous sandstone are revealed,and the factors affecting its strength and creep operation mechanism are analyzed.The specific research content is as follows:(1)The triaxial shear and creeep tests of different conditions are carried out in the strongly weathered argillaceous sandstone of Huaiba Landslide by SZLB-4 coarse-grained soil triaxial instrument.It is used to analyze the stress-strain characteristics,strength characteristics,particle breaking characteristics and creep characteristics of strongly weathered muddy sandstone.(2)The stress-strain curved edges of strongly weathered muddy sandstone all show strain hardening,which is composed of three stages of linear deformation,yield and hardening.And found that the essence of the shearing process is to use the shearing system as a medium to transfer energy to the particle system.(3)Confining pressure?the stone content and water content have an important influence on the shear strength and particle breakability of strongly weathered argillaceous sandstone.The higher the confining pressure,the higher the shear strength and particle breakage of the sample.The higher the stone content,the higher the shear strength of the sample and the internal friction angle of the 60% stone content sample is about 10 ° higher than that of the 35% stone content sample,and the particle breakage rate is 1-2 times higher.The higher the water content,the lower the shear strength of the sample,and cohesion decreases approximately linearly,and the particle breakage rate also decreased significantly.(4)The creep process of strongly weathered argillaceous sandstone is essentially a slow adjustment process of internal particles under external force,which is accompanied by complex strength loss and repair.The stress level plays a decisive role in the creep characteristics of strongly weathered argillaceous sandstone.It not only directly affects the instantaneous displacement amount and creep displacement amount of the sample,but also determines the creep stage.The water state also has an important influence on the creep characteristics of strongly weathered argillaceous sandstone.Compared with natural creep sample,saturated creep sample show a sudden increase in displacement at high stress levels and poor stability.(5)The linear method and CHEN' s method were used to process the gradation loading curves,then analyze the applicability of these two methods.Long-term strength determined by transition creep method and isochronous curves method,then compare long-term intensity and intensity parameters with instantaneous intensity.