Experiment Study On Mechanical Properties Of CSG Material

Cement sand and gravel dam is a new type dam which combines the roller compacted concrete dam and concrete faced rockfill dam that appeared in recent years.It is a new material made by adding cement and water to the rock-based materials such as the riverbed gravel or excavated waste materials that can be obtained easily near the dam sites and then mixed by simple equipment. CSG dam has significant advantages in optimizing the structure arrangement,saving construction investment,rapid construction,adapting to the natural environment and protecting the ecological.At present, the domestic research on CSG material is in the initial stage, the basic theoretical research is relatively small,the imperfection of the test method is still necessary to discuss,the system of mechanics index has not yet established,which are not conducive to the further development of CSG dam.In this paper,the research results that based on the summary of a large number of test data at home and abroad,combined with the national commonweal research project "cement sand and gravel material mechanical properties,durability and dam type research",systemtest and research has taken on the main factors affecting the mechanical properties of CSG materials aim to explore the discipline between material strength index and factors,establish a system of CSG material mechanics index system,obtain the following conclusions:1.Introduce the development and characteristic as well as the research status of CSG dam; in the view of CSG materials properties,combined with previous research results and practical engineering data to determine the test method;2.On the basis of a large number of experimental,study and analyze the amount of cement, content of fly ash,water-binder ratio,sand ratio,aggregate gradation,age and other factors that influence the compressive strength and splitting tensile strength of the CSG material,then explore the law of the axial compressive strength,flexural strength,compressive static variation of elastic modulus and flexural modulus of elasticity.On the basis of tensile and compressive strength to explore the inherent variation of the mechanical index.3.Through the large triaxial shear test,draw the corresponding stress-strain curves and the corresponding shear strength index,the stress-strain relationship can be divided into three typical stages:linear elastic,nonlinear and strain softening.In low stress level it shows linear elastic properties,with the stress increasing gradually it enters the nonlinear phase until it reaches the peak strength of the materials.Thereafter,with the strain growing,the stress reduces and shows obvious softening characteristics.Finally it tends to the residual strength of the materials.4.Researching on the rules of the strength of the CSG material,determine the inner relation of peak strength and confining pressure,strain values and the confining pressure,shear strength indexes like cohesive force and angle of internal friction under different mix proportion of CSG materials.Combined with the consolidated drained test,The relationship between axial strain and volumetric strain of material was discussed.Provide key parameters for the latter part of the establishment of the bulk modulus.