Study On Vibration Wave Propagation Mechanism And Response Characteristics Of New Cement-Based Grouting Material

New cement-based grouting material(NCG)has the advantages of no bleeding,100% hardening rate,controllable setting time,high early strength,superior fluidity and filling,environment friendly and so on.The NCG material to be used in barrier for vibration isolation has good basic performance and advantages in technical economics.According to the above background,the research on micro-characteristics,dynamic model,propagation mechanism of vibration wave and wave characteristics of NCGconcretion is carried out.In the field of science,the research enriches the theorys and achievements of porous multiphase media dynamics and vibration wave propagation,and in the field of engineering,it enriches the types of vibration isolation grouting materials,provides theoretical basis for expanding the application field of grouting materials,opens up new ideas for the application of vibration isolation technology,and provides research basis for the technology-combination of grouting filling,reinforcement and vibration isolation.The characteristics of solid-phase and pore-phase of NCG-concretion are analyzed by means of SEM&EDS,TGA-DSC,BET,MIP and 3D-XRM in combined with hydration reaction mechanism.The researches show that solid-phase skeleton of NCGconcretion is interwoven with the largest proportion of dendritic or columnar ettringite(AFt)crystals,which filled with calcium silicate hydrate gel(C-S-H)and aluminum gel(AH).The micro-characteristics of NCG-concretion are comprehensively and systematically analyzed,including: micromorphology,mass and volume proportion of solid phase,volume distribution of gel-phase,sphericity distribution and its dispersion characteristics of gel-phase,volume and quantity distribution of pore-phase,the most probable diameter of pore-phase,and sphericity distribution and its dispersion characteristics of pore-phase,etc..It provides a basis for further study of the performance parameters of NCG-concretion based on micro-characteristics.Combined with the porous multiphase media characteristics of NCG-concretion,based on the method of continuous medium and the theory of mixture,the dynamic model of porous multiphase medium is established: the kinematic characteristics of each phase of NCG-concretion is descripted,the mass conservation equation and momentum balance equation of porous multiphase medium are established,and the Bishop effective stress equation and constitutive relation to describe the stress characteristics of NCG-concretion are given.Combined with the systematic analysis of the micro-characteristics of NCG-concretion and the measurement of P and S-wave velocity,the basic parameters of NCG-concretion dynamic model were obtained,including: porosity,solid skeleton density,apparent density,permeability and related parameters,capillary pressure function and characteristic parameters,equivalent bulk modulus,shear modulus of solid skeleton,bulk modulus of solid skeleton,first Laméconstant of solid skeleton.The basic parameters above lays a foundation for the study of vibration wave propagation of NCG-concretion.According to the effective stress equation,three-phase volumetric strain equation,capillary pressure equation and fluid phase mass conservation equation in the NCGconcretion dynamic model,the seepage continuity equation of pore fluid is obtained.Combining it with the relationship of relative seepage acceleration mechanics,fluid momentum balance equation,stress-strain relationship of solid skeleton,the wave equation of porous multiphase media is established,which takes the elastic parameters of each phase component,viscosity effect,capillary pressure action,pore characteristics and permeability characteristics into account.The Helmholtz decomposition of threephase displacement is substituted into the wave equation of porous multiphase medium,and the divergence and curl operation are carried out.The general solution form of vibration wave is introduced,and the characteristic equations of P-wave and S-wave are obtained.The characteristic equations shows,there are three kinds of P wave(P1wave,P2 wave,P3 wave)and one kind of S wave in porous multiphase medium,and the expressions of wave velocity and attenuation coefficient of four kinds of the body wave are obtained.The variation of velocity and attenuation coefficient of the four kinds of body wave in NCG-concretion with wave-characteristic-parameters(frequency),state-parameters(saturation)and medium-parameters(porosity,pore size distribution index,solid skeleton elastic parameters)are analyzed and discussed.Based on the analysis to the variation of attenuation coefficient with relevant target parameters of P1 wave and S wave,reasonable application suggestions about medium parameters and state parameters of NCG material for vibration isolation are put forward.According to the porous and multiphase characteristics of the NCG-concretion,the equivalent medium parameters(bulk modulus,shear modulus and density)of three proportionings of NCG-concretion(W1N,W2 N,W4N)at five saturation levels(0%,25%,50%,75%,100%)were determined,and the corresponding numerical simulation model of finite difference method is established.The distribution of vibration peak value and vibration level with distance of four responses(acceleration,velocity,displacement and stress)under the action of P wave and S wave at seven frequencies(5 Hz,10 Hz,20 Hz,40 Hz,80 Hz,160 Hz and 320Hz)and the influence of proportionings,saturation and frequency respectively were analyzed.There are 111 pictures,13 tables and 217 references in this paper.