Study On The Formation Effect And Stability Of Advance Grouting Curtain In Roadway Under Dynamic Water Condition

In the process of roadway excavation,sometimes there will be various forms of water gushing point,which will bring difficulties to construction,increase investment,and even cause accidents like submerging the mine,bringing huge losses to the country and the people.Therefore,when the underground excavation project passes through the water rich area,such as aquifer and fracture zone,it is generally necessary to carry out advanced curtain grouting to isolate water,so as to ensure the safety of excavation.Taking the gushing water problem in-300 m and-350 m level roadway of open-pit to underground mine construction in Gushan Iron Mine as engineering background,the theoretical analysis,model test and numerical simulation were used.Firstly,the single-hole grouting test in dynamic water was carried out to obtain the formation law of single-hole grouting stone body.Secondly,the two-phase flow model and fluid-solid coupling model were established to reveal the formation effect of multi-hole grouting curtain in dynamic water.And then the stability of advanced grouting curtain after excavation was studied,and the quality evaluation method of advanced grouting curtain in roadway was proposed.Finally,the water inrush mechanism and curtain instability analysis were carried out for the water inrush disaster in the-300 m level roadway in Gushan Iron Mine,and a reasonable support scheme was proposed.The main research contents and achievements are as follows:(1)By using the self-designed test system for grouting in dynamic water which can be used for porous media and flat plate fractured media,the formation law of single-hole grouting stone body in different grouting media with different dynamic water velocity or grouting velocity was studied.(2)Based on the two-phase flow equation,COMSOL Multiphysics was used to simulate the process of model test,and the numerical simulation results were compared with the model test results.After verifying the rationality and reliability of the basic principle of numerical simulation,the 3D model of porous media for multi-hole grouting was established on the basis of actual engineering scale,and the formation effect of multi-hole grouting curtain under dynamic water condition was studied.(3)The 2D fluid-solid coupling model of rock mass was established,where the model parameters,load conditions and boundary conditions were set according to the actual engineering,to study the stability of curtain body formed under dynamic water after roadway excavation.Then the concept of "the minimum effective thickness" was introduced as the pre evaluation index of curtain quality.Based on the grouting data recorded in the engineering field,the concept of "the ratio of curtain to grout in roadway" and " the double value of roadway" were used as the post evaluation index of curtain quality.(4)Based on the proposed three quality evaluation indexes,the grouting curtain of-300 m level roadway in Gushan Iron Mine was applied in practice.Aiming at the water inrush disaster at-300 m level in Gushan Iron Mine,the mechanism of water inrush and the reason of curtain instability were simulated and analyzed,and the support and reinforcement technical scheme of roadway grouting curtain in water inrush area was proposed.There are 81 figures,8 tables and 100 references in this dissertation.