The Experimental Research On Diffusion Mechanism Of Clay-cement Slurry In Dual Fractures

For making the grouting parameters more suitable in high pressure water-bearing strata,this paper intends to explore the diffusion mechanism of clay-cement slurry in a grouting part which contains two fractures with different apertures.The main progresses are as follows:(1)Based on the fundamental equations of fluid and the constitutive function of clay-cement slurry,the author does some analytical calculations.For the case of constant grouting quantity,the approximate relationships among the reduction of slurry pressure,rheology parameters and geometric dimensions of fracture are proposed in diffusion region of a single-track fracture and dual single-track fractures.As for radical diffusion in the single plane fracture and dual fractures models,the author makes the similar analytical solutions about pressure deduction in diffusion region under the constant grouting flowrate condition.(2)Using the software,do some numerical simulations about clay-cement slurry in single fracture and dual fractures models,applying the fitting function of rheology parameters by virtue of UDF manner.The results show that the temporal variation character of rheology parameters would have more severe influence on diffusion of slurry as the time goes on,for a long period of grouting time.That can not be ignored.As for diffusion of slurry in two fractures,the increasement of aperture for any of them would change the pressure environment,the relationship between them is inverse correlation.Under the constant grouting quantity in dual fractures,the ratio of diffusion distances in two fractures is nearly same as the ratio of width of fractures.(3)A series of tests for clay-cement slurry in physical model with two fractures are conducted,using the experiment platform.The experimental phenomenon shows that the variable trend of grouting pressure is same as simulation results,but the value is more.The deposition of clay-cement slurry would make mutations of the grouting pressure.Compare with the simulation results of slurry in two fractures,it is thought that the deposition of clay-cement slurry has great influence on diffusion distance and slurry pressure.So,the clay-cement slurry can not be easily thought as generalized Bingham fluid,when it is used in practice.Also,the parts with larger pressure drop would have better effect on intercepting water seepage,during the grouting progress.