Dynamic Triaxial Test Study On Dynamic Characteristics Of Silty Sand In The Yellow River Flood Area

Silty sand is widely distributed throughout China,covering many provinces,of which the lower Yellow River is the most obvious.The Yellow River has been diverted and flooded for many times in history because of various reasons,resulting in the vast Yellow River flood area.The plasticity index of silty sands is Ip between 3~10,its lithology is loose,the grains are homogeneous,the grinding roundness is high,the porosity is high,the occlusal effect between them is poor,the clay content is lower.Under the action of earthquake,vehicle vibration and other loads,silty sand may produce liquefaction,which belongs to poor Engineering Foundation.It has important theoretical and practical value to study the engineering geological characteristics of silty sand in the Yellow River flood area.The dynamic triaxial test platform is used to study the dynamic charateristics of typical silty sand of Kaifeng.The main works and achievemengts are:(1)The classification of soil is determined by soil screening test,liquid-plastic limit test and compaction test,and the fine grain content,liquid limit,plastic limit,optimum water content and maximum dry density of silty sand are obtained.(2)The effects of different confining pressure,dry density and content of clay on dynamic strength and liquefaction strength are studied by taking dynamic strength test of silty sand.Then dynamic strength curve and liquefaction strength curve are obtained under different confining pressure,dry density and content of clay.(3)The effects of different confining pressure,consolidation ratio and water content on dynamic shear modulus are studied based on a large number of dynamic triaxial tests.Then obtain variation curves between dynamic shear modulus and dynamic shear strain and dynamic shear modulus ratio and dynamic shear strain are obtained under different influence factors.(4)The effects of different confining pressure,consolidation ratio and water content on damping ratio are studied by taking damping ratio test of silty sand.The damping ratio is calculated and compared with three methods.(5)Hardin-Drnevich constitutive model,Ramberg-Osgood constitutive model and Davidenkov constitutive model are used to fit the shear modulus ratio and shear strain curve of shear stress and shear strain strain curve.And the fitting effects of three constitutive models on the shear modulus ratio and shear strain curve of shear stress and shear strain strain curve of silty sand are compared and analyzed.The research results can provide some basis for aseismic design and dynamic analysis of geo-structure,and make it more scientific and economical in engineering design application.And enriching the dynamic characteristics of silty sand and providing reliable test data for relevant theories.