The Optimization Of Slurry Material And Slurry Flow Mixing Law During The Mud Replacement Of Freezing Hole

In recent years,the deep freeze sinking technology is gradually applied in shaft construction of watery strata,the mud replacement process of freezing hole has been developed,however,freezing pipes can not be successfully sank will still be the case in construction field.Therefore,in this paper,the method of indoor test,numerical simulation and physical model test is used to study the optimization of slurry material and slurry flow mixing law during the mud replacement of freezing hole.First of all,through laboratory test,super fine cement is added to the original formulation,which study on performance optimization of retarded cement slurry.The results show that the addition of super fine cement to the slurry has little effect on the initial fluidity of the slurry,but the initial setting time of the slurry is reduced.Compared with the initial viscosity,the rate of stone,the initial setting time and the rate of water splitting,the content of super fine cement in cement slurry should be 20%~40%.The addition of retarder and dispersant in the slurry,the stability of the mixed ratio 40% of the super fine cement is better than that of mixing ratio 30% and 35%.After adding the same proportion of suspending agent,the suspension stability of the cement slurry with the mixing ratio 40% was higher than that of the cement slurry with the mixing ratio 30% and 35%,and the initial fluidity of the retarded cement slurry was good.The new and original formulation of the retarded cement slurry mixed with mud in different volume ratio,the apparent viscosity of mixed slurry slowly increased at first,then decreased rapidly with retarded cement slurry ratio is increasing;the viscosity of new formulation mixed with different proportion of mud are whole slightly larger than the original formulation.The initial setting time of the mixed slurry decreases first and then increases with the increase of the proportion of the retarded cement slurry.Secondly,through indoor experiment,the research of isolation solution was carried out.The results show that the xanthan gum content reached 0.45% of the mass of barite powder,suspension performance and flow performance is very good.Sulfonated lignite resin mixed with 2%,the filtration rate as 55 ml,significantly less than the sodium lignosulfonate and sodium naphthalene.Determined the isolation liquid density of 1.30 g/cm3 composition: 1.77 water +1 barite powder +0.45% xanthan gum +2% sulfonated lignite resin.The compatibility of the spacer liquid with the mud and the retarded cement slurry is good,and the suspension stability,the filtration performance and the rheological property of the different density of the spacer liquid are good,which can meet the construction requirements.Then,through the numerical simulation,the mixing rule of slurry flow in slurry displacement and the variation of the height of mixing section under different conditions are studied.The results show that the annular mixing section height h of the 5%~95% of volume fraction is first increased and then decreased with the slurry flow increasing;h is decreased first and then increased with the increase of wall roughness;h is first increased and then decreased,and then increased with the drill pipe diameter and aperture ratio;h is first decreases and then increases and then decreases with the change of slurry rheological parameters;h is decreased firstly and then increased with the increase of drill pipe eccentricity,and h2 increased.At the same time,the minimum volume of the spacer fluid under the most unfavorable conditions is studied.By range analysis and variance analysis of orthogonal test,The order of the factors affecting h2 and the order of significance were the same,as follows: drill pipe eccentricity > grouting flow > ratio of drill pipe diameter and diameter > slurry rheological parameters> the surface roughness;The factors of wide gap mixing section height h(5% ~ 95%)significantly affected by grouting flow > drill pipe eccentricity > surface roughness > slurry rheological parameters > ratio of drill pipe diameter and diameter.At last,through the physical simulation experiment,the flow mixing law of slurry in slurry displacement process is studied.The results showed that the mixing section height h,obtained from the physical test,is increased with the increase of flow rate,but the h increases slowly.The corresponding numerical simulation results show that with the increase of flow rate,mixing section height h increases first and then decreases,but the decreasing trend is very small;the results of mixing section height h in physical test are larger than the results in the numerical simulation and analyzes the possible influencet factors.