Study On The Properties Of Rheology-Solidification Of Time-depending Viscous Grout And Diffusion Mechanism

The Qinghai Tibet Plateau and its surrounding areas in Southwest China experienced orogeny and magmatic activities,forming the areas with strong undulation and the most complex geological structure in the west of China.The shallow and deep structures of the rock mass developed.In the process of infrastructure construction,there must be engineering geological problems such as water inrush from tunnel construction,deep cracks in highway and hydropower slope,seepage control of water conservancy and hydropower foundation and so on.For these problems,grouting is usually used to deal with it.Whereas,the uncontrollable setting time and unpredictable diffusion of cement sluury cause the problems of large leakage,low filling rate and low strength when dealing with large and steep dip cracks,high-pressure water gushing.The perforcemence of cement grout can be changed by adding chemical additives.Therefore,it is one of the key and difficult points in the field of grouting materials to study the additives and the hydration-rheology-hardening characteristic of cement-based grout.In this paper,a kind of viscosity time-depending grout is developed for plugging steep wide cracks and water gushing strata.The rheological property of the grout is studied from the macroscopic rheology through the fluidity test and rheological test;the viscoelasticity of the grout is studied through the small amplitude oscillation test and thixotropic test;the mechanical property of the viscosity time-depending grout is analyzed by the compression and tensile test,and the durability of the grout is studied by the freeze-thaw cycle test;Based on the meso statistical damage mechanics,a freeze-thaw damage constitutive model including damage threshold is established;through the hydration heat test,observation of meso structure and products,the hydration rheological hardening mechanism of grout is revealed,and then the hydration model is established,and the relationship between the meso structure and macro characteristics of grout is established;through the simulation test,the diffusion rule of viscosity time-depending grout under the dry and static water conditions is studied;A single plane crack grouting diffusion model is established by numerical calculation.Through engineering application,the effectiveness of grouting technology with time-depending viscosity grout to block the high-pressure water gushing channel is verified.The judgment of high-pressure water gushing channel and the criterion of blocking effect are established based on the characteristics of pressure change in the grouting process.The mainly includes of the thesis as following:(1)The rheology-solidification charactristic of viscosity time-depending groutThe cement-based viscosity time-depending material based on organic material modification was developed,and the grout with different proportion was prepared.It is found that the initial fluidity of the viscosity time-depending grout is similar to that of the pure water grout with the same water cement ratio,but its fluidity is obviously timedepending and the pumpable period is controllable;the yield stress and viscosity of the grout increase gradually with the increase of the pumpable period,with obvious timedepending;the viscosity time-depending grout is viscoelastic and thixotropic during the pumpable period,which can be restored in a period of time.The rheological and solidification characteristics of grout are affected by the amount of admixture and water cement ratio.Based on shear rate,shear stress and viscosity,a rheological model of viscosity time-depending grout was established.(2)The strength and durability of stone body of viscosity time-depending groutThe thesis studied the influence of the amount of admixture on the early compressive strength and splitting tensile strength of the stone body,which revealed the improvement of the physical and mechanical properties of the stone body by admixture;studied the deterioration rule of the physical and mechanical properties of the stone body and the influence of the amount of admixture through the freeze-thaw cycle sample;analyzed the improvement mechanism of the admixture on the durability of the cement stone body through the macro and micro scale;based on meso damage statistical mechanics,a constitutive model including damage threshold is established.(3)The hydration-rheology-hardening mechanism of viscosity time-depending groutAccording to the principle of hydration thermodynamics,the exothermic heat of the hydration process of the viscosity time-depending grout was measured to divide the hydration process into stages.Based on the principle of hydration reaction kinetics and the equation of cement hydration kinetics,the reaction mode,rate and degree of hydration of each hydration stage were distinguished.the results shown that the hydration of the viscosity time-depending grout can be divided into five stages,and the hydration reaction of each stage was affected by the type and amount of additives.Through ESEM and XRD,the structure of hydration products of viscosity timedepending grout was analyzed from micro scale,and the relationship with rheology,solidification and physical and mechanical properties of stone body was established.The action mechanism of admixture on cement grout was revealed from hydration mechanism and micro scale.Finally,the hydration solvation membrane secondary hydration model of viscosity time-depending grout was established.(4)Grouting diffusion mechanism of viscosity time-depending grout and diffusion model in single plane crackBased on the study of momentum balance and mechanical balance,the diffusion equation of grout between parallel plates is established,and the diffusion radius and diffusion limit of grout with fixed grouting pressure are solved by the finite difference method;based on the balance equation,continuous equation and geometric equation,the diffusion velocity equation and diffusion radius time equation of single plane fracture grout with viscosity time-depending grout are established Based on the geological parameters,grouting parameters and grouting parameters,a grouting diffusion simulation test device is established to systematically study the diffusion form and diffusion rate of the grout under the conditions of different inclined fissures and water bodies,and to verify each other through comparison with the theoretical model.The results show that the diffusion form of grout in horizontal fracture is approximately circular,and the diffusion in inclined fracture is asymmetric elliptic;the diffusion rate and radius are affected by grouting pressure and yield stress of grout.Based on the time-depending viscosity grout,the controllable grouting technology was established,and the field test of plugging high-pressure water gushing borehole was carried out.Based on the characteristics of the pressure change of the orifice during the grouting process,a method for judging the water gushing channel and evaluating the grouting effect based on the grouting pressure is established.