Study On Mechanical Properties And Damage Mechanism Of CSG

In this paper,Uniaxial compression and splitting tensile tests were carried out on cemented sand and gravel(CSG)materials through laboratory tests,and figure out the effects of stress-strain curves,fly ash and silica fume contents and freeze-thaw cycles on automatic capabilities of CSG mediums were obtained.The stat istical da mage cons titutive model was defined,the changing rule of the macroscopic impair constants were analyzed,and unveil divergent points on the mesoscopic damage evolution mechanism of gelation and gravel.Through the statistical damage constitutive model in ANSYS secondary development,the model is Oyuk dam,after elaborating the numerical simulation for gelling gravel dam damage process for digital research.Main work content is as follows:(1)By changing the content of six kinds of fly ash,two batches of cylindrical cementitious sand and gravel specimens were made,and uniaxial compression and splitting tests were carried out respectively.With fundamental model of monaxial compression/monaxial tractile stress-strain curves,studies its mechanical capability.Results showed that the gross total,fixed gelled stuff pattern under monaxial compression,with stage by stage adding dose of fly ash,the CSG materials’compressive resistance and the coefficient of elasticity are less and less,and peak strain overall showed a trend of decrease;When specimens in tension,the CSG materials’riving extendible power decreases with enhance the fly ash dosage.(2)By replacing cement with 6 kinds of silica powder,two batches of cylindrical cementified sand and gravel specimens were fabricated.Uniaxial compression and split tensile tests were carried out respectively,and the full stress-strain curves of uniaxial compression/uniaxial tensile were obtained.The mechanical properties of the specimens were studied.Results showed that the dosage of silicon powder on gelation and gravel specimen macroscopic stress-strain behavior affect significantly,specimen under uniaxial compression,with the improvement of silicon powder dosage,CSG materials’compressive resistance and the coefficient of elasticity are gradually increase,the peak strain improve with the fall off of the first;When specimens in tension,the gelation of sandy gravel material splitting tensile force is gradually adding with enhance the silicon fume dosage.(3)Three freeze-thaw cycles were considered to carry out freeze-thaw tests on cube cemented sand and gravel specimens respectively,and the effects of different freeze-thaw cycles on the surface morphology of the specimens were observed.Then,starting the uniaxial compression and splitting tests,getting the monaxial compression/monaxial tractile stress-strain curves,studying its mechanical capability.Results showed that with enhance the number of freeze-thaw,CSG materials’compressive resistance and the coefficient of elasticity are less and less under uniaxial compression,and peak strain improve with the fall off of the first;When specimens in tension,the CSG materials’riving extendible power decreases with enhance the freeze-thaw cycles.(4)The uniaxial pressure elementary model given the capacity of fly ash,silica fume and times of freeze-thaw cycles was defined.The variation rules of five meso-damage parameters E、ε_a、ε_h、ε_b、H were analyzed respectively.The expressions of the variation of the five parameters with the content of fly ash,silica powder and times of freeze-thaw cycles were obtained by fitting.(5)Through the secondary development of statistical damage constitutive model in ANSYS,uniaxial compression and uniaxial tension are taken as the basic macroscopic failure modes,and fracture damage and yield damage are considered at the same time.In Turkey Oyuk dam for the model,by using static analysis and overloading analysis,the stress of the dam body and the damage distribution,analyze the location of the dam body cracks and extension process.Select on behalf of the unit,analyze the overload at different location of the dam horizontal displacement in the process of development trend.