Investigation On The Propagation And Sealing Efficiency Of Grouting In Fracture Network With Flowing Water

Grouting is an effective method to control water inrush in underground engineering has been used widely.It is necessary to study the propagation and sealing efficiency of grouting in the fracture network with flowing water based on the past achievements and experiences.The physical modeling is used to investigate the propagation characteristics of grouting,sealing efficiency and its influences factors and the effect of water on the propagation of grouts.Finite element numerical simulation is used to simulate the grouting in fracture network with flowing water,and the results are compared with the physical modeling.The main contents and results are as follows:(1)The sealing effect is calculated by the existing formula and the grouting efficiency is divided into six grades by the sealing effect.The relationship between water flow and time are divided into four types by the change characteristics,and there is a great difference between the sealing efficiency and the retention of grout in different types.(2)The influence factors of sealing efficiency are analyzed by means of the method of range analysis and variance analysis.The results show that the factors for controlling grouting efficiency followed by the initial water flow speed,the fracture aperture,the grout take and gel time.(3)MATLAB is used to process digital images and the propagation characteristics of grouting are obtained.The grout propagation behavior in the fracture network is divided into three types: sealing off,partially sealing and major erosion.Finally,the edge scouring mechanism is proposed.(4)Grouting pressure and seepage pressure are analyzed and it is observed that the grouting pressure and the seepage pressure will be different under different sealing efficiency condition.The sealing efficiency is very nice when the seepage pressure all increases.When the partial rise and fall,the grouting type is partially sealing and grouting failure occurs when all the seepage pressure drops.(5)The influence of water on the propagation of grout is investigated by the comparison tests.It is observed that the propagation morphology of the grout is ellipse and the dilution effect of water has little influence on the propagation morphology of the grout in anhydrous and hydrostatic environment.The grout propagate to the downstream firstly under the hydrodynamic condition.Water erosion and the dilution effect is more obvious in the grouting body sides and downstream.(6)The anisotropy of the grout propagation is analyzed and it is observed that the anisotropy is more obvious caused by rock fracture aperture with flowing water.The anisotropy occurred when the aperture of the two groups of fracture is different and the anisotropy is more obvious when the greater the difference between the two groups of fracture aperture.(7)Numerical simulation results show that the fracture aperture,the initial water flow speed and the grout take have influence on the propagation characteristics of grout while the gel time has little influence on the propagation characteristics of grout.The initial water flow speed,the fracture aperture,the grout take and gel time all have influence on grouting pressure.