Study On The Law Of Diffusion Of Cement Slurry In The Construction Of Perfusion Pile

Based on a foundation project in nyingchi city,Tibet autonomous region,this thesis studies the fluidity index,composition analysis and performance influencing factors of cement slurry.Combined with the parameters of geotechnical weight,permeability,viscosity coefficient,porosity,internal friction Angle,sand content and so on.For cement slurry in the theory of diffusion in geotechnical engineering research,combination calculus principle of calculus in diffusion equation,and nyingchi city in combination with an engineering case,through the combination of theory and practice to explore the application of theoretical formula,summarized suitable for grouting diffusion theory with the project area.It provides theoretical basis for grouting design and construction of cast-in-place pile.In this process,the main work of this thesis is as follows:(1)The basic parameters of an engineering rock-soil mass in nyingchi city were studied by combining the data obtained from the N120 super-heavy power contact test and the rotary drilling test of xy-150 drilling rig with the engineering experience data.which served as the basis for the diffusion theory of cement slurry in the rock-soil mass medium.The parameters such as the weight,permeability,porosity,internal friction Angle,viscosity and sand content of the rock and soil mass of the project were determined.(2)The basic properties of cement slurry in practical application of this project are measured and calculated by experiment combined with theoretical model,and the calculation formulas of the fluidity index of cement slurry and the viscosity of cement slurry at different water cement ratios are determined.The diffusion principle and path of cement slurry with different water cement ratio in geotechnical medium are also explored.Through the relevant data rules of cement slurry test,it is found that the viscosity of cement slurry with larger water cement ratio increases with the increase of temperature,and the viscosity decreases with the decrease of temperature,and the relative change is not significant.The shear force increases with temperature under the condition of low water cement ratio slurry with the same viscosity,while the viscosity decreases with the increase of temperature for high water cement ratio slurry.The positive correlation between the porosity and the fluidity of cement slurry and the diffusion of cement slurry in geotechnical medium is determined.(3)By measuring and analyzing the fluidity index of cement slurry,it is found that when the water cement ratio is small,the fluidity of cement slurry has a non-linear relationship with time,which does not conform to the basic properties of Newtonian fluid,but is consistent with the flow law of Bingham fluid.Therefore,it can be characterized by the flow law of Bingham fluid.Based on the motion equation and equilibrium equation of cement slurry,the diffusion equation of cement slurry when it belongs to Bingham fluid is determined by calculus.(4)Measuring and analyzing the fluidity index of cement slurry.It is found that when the water cement ratio is large,the fluidity of cement slurry has a linear relationship with time,which can be approximated as Newtonian fluid.By combining the basic equation of Newtonian fluid with the equation of motion of slurry,the diffusion equation of cement slurry in Newtonian fluid state is deduced by calculus principle.(5)To study the practical application value of the derived diffusion formula.The diffusion equation of cement slurry is applied to a project in nyingchi city.The variation law of the pressure at the measuring point is explored with the increase of the diffusion distance.The pressure decreases numerically with the increase of slurry diffusion distance.