Experimental Study And Engineering Application On Plugging Mechanism Of Dynamic Water Grouting In Karst Pipeline

With the development of underground engineering in our country,a lot of geological disasters are often induced in the construction of tunnels,hydropower stations,inter basin water transfer and deep mines due to their complex geological conditions,among which karst water inrush is the most serious.Generally,the water body in Karst pipeline is in a state of pressure,with large amount of water and water pressure,which makes it difficult to control.During the excavation of the project,large flow and high velocity karst pipeline water inrush can often be exposed.The research on the mechanism of flow control and velocity reduction and dynamic water grouting plugging of karst pipeline is mainly carried out from the aspects of large-scale karst pipeline simulation test,numerical calculation software and field engineering application.The research results are applied to the pit water control project of Hejing phase ? limestone mine of China Resources Cement(Pingnan)Co.,Ltd.The main research contents and achievements are as follows:(1)A visual grouting simulation test system is developed,which consists of six parts:pipeline system,flow control and speed reduction system,water supply and pressure stabilization system,grouting system,multiple information monitoring system and slurry treatment system.The system realizes the real-time observation and image information acquisition of slurry diffusion and deposition form in the process of dynamic water grouting,realizes the real-time collection of data such as fluid pressure and dynamic water flow rate,and the test system can meet the requirements of the research on the plugging law of dynamic water grouting in Karst pipeline.(2)The initial and final setting time of cement water glass quick setting materials are studied.Based on the above test system,the sealing law of pipeline under static and dynamic water conditions is studied,and the temporal and spatial variation law of pressure field and velocity field is analyzed.The orthogonal test method is used to study the influence of different grouting parameters,material ratio and other factors on the grouting and plugging of pipelines,and the optimal combination form under different working conditions is obtained.(3)In this paper,the flow control experiment was carried out,and the variation of velocity field and pressure field under different water head,pipe diameter and valve opening were studied.The numerical method is used to carry out the simulation analysis of the flow control and speed reduction of the pipeline,which verifies the accuracy of the test results.On this basis,the research on the rule of slurry diffusion plugging under different flow control conditions is carried out,the slurry deposition thickness is analyzed,and the optimal combination form of dynamic water plugging under different conditions is obtained by using the orthogonal test analysis method.Furthermore,the thickness ratio of slurry deposition is taken as the evaluation index,and the influence of flow control on pipeline grouting is analyzed quantitatively.The results show that the flow control can effectively improve the plugging rate of slurry.(4)The results are applied to the pit water control project of Hejing phase II limestone mine of China Resources Cement(Pingnan)Co.,Ltd.The pressure test is carried out on the flow control and deceleration device of Y02 and Y03 water inrush points to verify the flow control and deceleration equation.Through the application of the theory of borehole grouting and grout stopping pad to control the flow and speed down,the foundation is laid for the plugging of water gushing points,and the important theoretical and technical achievements and reference experience are provided for the treatment of karst water in similar mines in China's karst areas.