Experimental Study On Water Plugging Mechanism Of Organic Grouting Material Under Engineering Water Inrush Condition

The grouting technology is one of the most effective means of controlling water inrush disaster at present,the traditional grouting with cement slurry、water glass grouting material,can handle small scale water inrush.In the face of large engineering water inrush with high temperature conditions,the anti dispersity of the slurry is poor and easy to be dispersed and diluted by water,failing to pligging the crack.The organic chemical grouting material can make up the deficiency of the traditional grouting material.Water soluble polyurethane chemical material(WPU)is a low viscosity single component polymer grouting material;when mixed with water,slurry will solidify with the volume expansion,but the resistance to dispersion,anti shrinkage and adhesion remains to be improved.In order to improve the properties of water-soluble polyurethane grouting material,the hydroxypropyl methyl cellulose(HPMC)is added in to improve the mechanical properties,anti dispersion and anti shrinkage properties of the slurry.Based on the experiments,the effects of hydroxypropyl methyl cellulose content and temperature on the air entraining property,gelation time,water swelling rate,bond strength,tensile shear strength,kinematic viscosity,free deposition diffusion and microstructure of water-soluble polyurethane grouting material were studied,and the optimum content of hydroxypropyl methylcellulose in grouting material is obtained through data comparison and analysis.Through the design and establishment of a transparent visual water crack grouting test platform,the modified grouting material is used to the dynamic water grouting simulation test,the feasibility of grouting for water plugging is analyzed,the diffusion law of the slurry in the water fissures is obtained,and the formula of the grouting diffusion radius is derived,which is used to guide the engineering practice.The main contents and results of this paper are as follows:(1)The characteristics of grouting diffusion sealing process,failure type of slurry in fissure and characteristics of water inrush are analyzed.It is concluded that the grouting material used to treat engineering water inrush should have the characteristics of anti dispersion,short solidification time,far enough diffusion distance,close fitting with crack surface,anti scour,sufficient durability,safety of personnel operation,convenient construction operation and so on.(2)The addition of hydroxypropyl methyl cellulose to water-soluble polyurethane has an air entraining effect.The number and equivalent diameter of bubbles in the slurry will increase with the increase of hydroxypropyl methyl cellulose content,and the change of temperature and hydroxypropyl methylfibrin content can affect the gelation time of the slurry,in a certain temperature range,hydroxypropyl methyl cellulose shows a retarding effect on water-soluble polyurethane grouting material.The effect of temperature on the cementitious time is greater than that of a certain temperature.The increase of hydroxypropyl methyl cellulose and the rise of temperature will increase the swelling rate of water in the slurry,and the effect of temperature change on the swelling rate of water is greater;The hydroxypropyl methyl cellulose can significantly improve the bonding strength and tensile shear strength of the slurry.(3)The addition of hydroxypropyl methyl cellulose to water-soluble polyurethane grouting material can increase the viscosity and density of the slurry.The viscosity increases slightly when the content of hydroxypropyl methyl cellulose is low in the slurry;the viscosity of the slurry increases rapidly when the content exceeds a certain range,and the addition of hydroxypropyl methyl cellulose to water soluble polyurethane grouting material can significantly improve the working temperature of the slurry.So that the slurry can diffuse at higher temperature and keep the diffusion effect unchanged.(4)The microstructure test results show that HPMC can effectively reduce the heterogeneity of the slurry with the slurry,eliminate the pore structure in the slurry gel and make the surface smooth and uniform,and the increase in temperature will reduce the number of heterogeneous components in the serous gel but increase the individual area.(5)The optimum content of hydroxypropyl methyl cellulose is 8%,it can improve the diffusion distance and blocking area of the slurry;the diffusion and migration of the modified slurry in the water fissures can be divided into the displacement diffusion stage,the inhomogeneous diffusion stage and the two expansion and diffusion stage,which can describe the characteristics and laws of the diffusion change of the modified grouting material.According to the grouting theory and the characteristics of the modified slurry,the formula of the grouting diffusion radius is derived,and the accuracy and consistency of the formula of the grouting diffusion radius is verified.It shows that the diffusion law of the modified grouting material can be reflected to a certain extent,and the diffusion radius of the grouting can be predicted,and it has a certain guiding role for the engineering practice.