The Key Water-blocking Technology By Fixing Freeze Tubes Along Whole Borehole

The deep-freezing method is the most important drilling method in complex aquifers.In the process of popularization and application in recent years,more than a dozen shaft flooding accidents caused by water diversion in the hole have occurred.Both domenstic and abroad,due to the failure to achieve the full length of frozen hole sealing pipe,resulting in frozen hole guide water engineering accident.In order to develop a new technique for freezing and sealing the full length of frozen holes,the numerical simulation and physical simulation methods are used to study the key water-blocking technology by fixing freeze tubes along whole borehole and the mixing rules of the new process.Firstly,a new Key Water-blocking Technology by Fixing Freeze Tubes along Whole Borehole by using a freezer is researched and proposed.The preliminary design of the quick freezing pipe pressure test device at the upper end of the freezing pipe and the unidirectional pressure pulping device at the lower end of the freezing pipe have been carried out.The process has the advantages of strong controllability,saving time and cost,and reliable effect.Secondly,the numerical simulation method was used to study the flow and mixing rules of three fluids: grout,water,and mud in the three stages of grouting,pressurizing water,and pipe washing.In the grouting stage,the diameter combination of the freezing hole-freezing tube-supply tube,the grouting flow rate,the roughness of the frozen hole wall,the eccentricity of the freezing tube,the change rate of the pore diameter of the freezing hole,and the skewness of the freezing hole were studied.Under such factors,the laws of flow and mixing of cement slurry,water,and mud are affected.It was found that the pressures in the freezing hole,the freezing pipe,and the liquid supply pipe all follow the rule of first decreasing and then increasing;the displacement effect of the fluid in the turbulent state is good;freezing hole in the frozen tube eccentricity is smaller,the effect is better.In the water pressure stage,the mixing rule of the fluid in the freezing pipe under different flow conditions is studied.It shows that the height of the mixing section of water and cement slurry in the liquid supply pipe under the laminar flow condition is smaller than that in the turbulent flow state.In the press water,the height of the mixing section can be effectively reduced by adding the spacer liquid.In addition,the flow law of the fluid in the freezing pipe under the circulation conditions of the positive and anti-wash pipes was studied separately during the pipe washing process.It is recommended to clean the frozen pipe by reverse circulation cleaning.Finally,the similarity criterion was deduced and the transparent similar slurry was studied.According to the main influencing factors,the flow and mixing rules of the cement slurry,water and mud in the freezing hole solid-pipe process were studied by physical simulation method.The experimental results show that the cement paste pressed from the liquid supply pipe can fully displace the drilling mud,and the reverse circulation pipe washing method can quickly clean the residual cement slurry in the liquid supply pipe,thus verifying the feasibility of the key waterblocking technology by fixing freeze tubes along whole borehole.The research results of this paper have important practical value for the development and improvement of deep-freezing drilling technology.