Mechanism Of Curtain Wall Grouting In Large Cave Under Dynamic Water Conditions

The problem of karst groundwater has been restricting the development of mining technology.For large underground cavities in water-rich mines,the method of forming walls through curtain grouting can not only achieve better anti-seepage and plugging effects,but also reduce the loss of slurry to a certain extent,which has good economic and environmentally friendly.Curtain wall grouting is an effective method to solve the problem of underground water in mines.At present,there is still a lack of scientific theoretical research on its grouting into walls.This paper takes the Chengmenshan copper mine with developed karst and rich groundwater as the background.The mechanism of curtain wall formation of large-scale voids under certain conditions is studied,the theory of grouting wall formation is perfected,and the mine construction and environmental protection are further promoted,so as to achieve the purpose of reducing the economic cost of mine grouting.The main research contents and conclusions are as follows:(1)The rheological and physical properties of the curtain wall grout were studied.The Herschel-Bulkley model was used to fit the rheological equations of the two slurries within 0～60mins.In addition,the initial setting time of the two slurries was within 1～3 hours,and the final setting time was adjustable within 2～4 hours.The water separation rate of the slurry is low(less than 5%),and the stone rate is high(greater than 95%).It belongs to the extremely slightly permeable level and can be used for filling and sealing karst caves.(2)Under anhydrous conditions,the process of slurry accumulation into a wall is divided into three processes,namely,slurry extrusion,slurry diffusion accumulation and solidification pressure.According to the mechanical analysis of slurry diffusion accumulation and solidification pressure,the curtain pressure The physical and mechanical equation of the slurry-forming wall accumulation is mainly composed of the height accumulation formula and the critical failure formula of the accumulation;The wall anti-scour equilibrium limit equation compares the relationship between the water flow drag force Fh,the cohesion force Fm of the accumulation body,and the static friction force Fn,and obtains the evaluation method of the water flow drag force on the stability of the accumulation body.(3)Through the curtain grouting test in the indoor model box without water,the accumulation data of No.1 grout grouting test and ② No.grouting accumulation test,including diffusion radius,contact angle and height,are sorted out.And compared with the data obtained from the physical and mechanical equation of the curtain grouting into the wall accumulation body,the validity of the theoretical equation is demonstrated,and the reason for the error is explained;The curtain grouting test under dynamic water conditions restores the on-site grouting equipment and simulates the curtain grouting process.A seepage-proof wall is formed in a dynamic water environment with a water flow rate of 0.1m/s,and two sides of the wall are formed.With a head difference of 31cm,there is no obvious dragging phenomenon of water flow and slurry on the low head side,which is consistent with the evaluation of its stability by the limit equation of anti-scour balance of curtain grouting into a wall.(4)According to the pre-set 5m staged wall formation under the assumptions,COMSOL Multiphysics software was used to simulate the curtain grouting under dynamic water conditions for the original size large karst cave,and the constitutive equation of dynamic water grouting was constructed.The results show that The shape,height and water erosion resistance of the accumulation are consistent with the theoretical analysis of the wall formation,and the differences between the simulated grouting accumulation and the laboratory test accumulation are compared,and the validity of the wall formation mechanism and the constitutive equations are further verified.