Study On Material Characteristics Of Cemented Sand,Gravel And Rock By Taguchi Method

The Cemented Sand,Gravel and Rock(CSGR)is a kind of rigid lean concrete with high water-binder ratio and low cementitious material content.CSGR dam is a new type of dam,conforming to "materials suitable structures" and "structures suitable materials",which is more economical and environmentally friendly because it has the advantages of local materials,overtopping and saving investment,however,the particle size of aggregate in the dam body can reach 150 mm,cofferdam up to 300 mm,which needs to be compacted by vibration of large construction machinery to achieve compactness.Therefore,laboratory tests are inevitably influenced by aggregate gradation and specimen size effects.At present,there is no research on the characteristics of CSGR materials under the multi-factor and multi-level synergistic effect,but a large number of material test studies mainly use single factor rotation analysis method,the research results are quite different from the actual research problems,and the conversion rate of the results is greatly reduced,so that the material test research often lags behind the engineering reality.In this paper,the limitation of single-factor rotation analysis is overcome by the Taguchi method,four-factors and three-levels of mixing ratio were designed for CSGR materials.Research on the working performance,impermeability and mechanical properties of CSGR materials under the synergy of four-factors,including unit water consumption(W),unit cement consumption(C),unit fly ash consumption(F)and sand rate(S).Quantitative analysis by using various methods of mathematical statistics,in order to find the hidden statistical laws behind the randomness of the data.The quality grade of the anti-permeability protection was evaluated qualitatively.The results show that:(1)The W and F are the main influencing factors of VC value and compressive strength.The F has a significant effect on improving the working performance and mechanical properties of CSGR;VC value is inversely related to W,F,C and S,and the compressive strength is negatively correlated with W and S,while positively correlated with F and C;The impermeability of the secondary CSGR material is very poor,so surface protection measures should be taken.(2)The factors influencing the stability and size of the VC value,the 60-day compressive strength and the 90-day compressive strength in order from strong to weak according to the degree of influence are W,F,C,S;F,W,C,S;and W,F,C,S,respectively,besides,adopt the contribution rate to quantify the result,the increase of S from 24%to 30%has no significant effect on the VC value and compressive strength,finally,The optimal mix ratio combination of the stability and size of VC value and compressive strength are determined.(3)The multiple linear regression model of VC value and compressive strength under the combined four-factors action of W,F,C,S was established,and the contour map was drawn,thus establishing a multi-index control system,which has important guiding significance for the preparation of CSGR materials conforming to "materials suitable structures" and "structures suitable materials".Based on Taguchi method,this paper studies the properties of CSGR materials,such as working performance,mechanical properties and impermeability,which enriches the mix ratio design of multi-index control system and provides new design ideas for the mix ratio design of CSGR materials in practical engineering.