Study On Mechanical Properties And Improvement Of Strong Altered Granite

Granite stratum are widely distributed in south of China,in which a certain pumped storage can power station project area of exploration adit and bank slope and there is a lot of loose strongly altered granite,the dam and other hydraulic structures provide the natural building materials.Strongly altered granite belongs to clayey silty sand,mainly including kaolinite,montmorillonite and other minerals composition,through in-depth analysis of the physical and mechanical properties of the samples.The main contents are as follows:(1)Did have a strong grasp of altered granite basic physical properties and mineral composition and the relationship between the degree of compaction and mechanical properties of the.Compactness as control index,examined the degree of compaction and permeability coefficient of relationship,and compressive deformation index of the relationship,degree of compaction and the shear strength index of the relationship,in addition found strong inhibition altered granite after soaked and saturated by the amount of compression increase meets the water softening,strength decrease water stability was poor.Do not conform to standard of hydraulic filling,should not be directly used in engineering,the need for improvement.(2)The use of cement and lime as a modifier of strongly altered granite modified research.The design of different lime ratio of permeability coefficient and compression index with lime ratio variation,two modified materials were significantly improved.Using polynomial shear strength index,including c、ccu、c’、φ、φcu、φ’ with ash ratio were fitted.Ash ratio increasing,the strength of cement soil increased gradually,and the lime soil in 5%~7% ash ratio between peaked.The improved sample shear stress and shear strain and three triaxial test stress-strain curves showed the characteristic of strain softening.(3)Comprehensive comparison of two kinds of improved soil properties determined the improvement program.Nature of the comparison of two kinds of improved soil,lime soil permeability is low,reservoir water level after landing easy to have a return,is not conducive to the dam’s stability;better water stability of cement soil,shear strength increment is also more obvious,encounter water softening shortcomings is improved and the determined optimized improvement scheme is 5-7% ratio of lime and fly ash cement improved soil,and the Duncan Chang constitutive model calculated modified material model parameters,the parameters provide the needed for the analysis of embankment engineering in the numerical calculation.(4)Using Geostudio software to optimize the selection of improved material filling simulation of homogeneous dam,the reservoir water level of different lifting rate,stability of downstream slope unsteady seepage characteristics of the dam and the corresponding seepage.