The Research Of Blasting Cumulative Effect On Grouting Curtain Water Sealing Properties

The mining open pit in Karst region in the south of China,where is face that complicated engineering geology and hydro-geological problems,especially with serious water burst and water inrush in mining with heavy water.Grouting curtain as an effective water stop technology is widely used in the mining with heavy water.The grouting curtain body has to undergo several blasting load disturbances,and the plugging effectiveness of grouting curtain body is a key factor to evaluate in mine mining.The background is based on a project of cement mine mining and water gushing in Changde,Hunan,which choose the grouting curtain body of the south slope of mine pit as the research object to study the influence of blasting cumulative effect on plugging performance of grouting curtain.(1)Two types of grouting curtain rock samples are prepared along the axial,axial and lateral simultaneous opening(combined opening),and the damage-seepage coupling test of the grouting curtain rock samples under cyclic loading and unloading is carried out.The effects of different peak stress levels,confining pressure,seepage pressure difference and curtain filling form on the permeability and damage evolution of the grouting curtain rock sample are analyzed.The test shows that the peak stress level is the main factor affecting the development of the grouting curtain rock sample damage;high confining pressure can reduce the damage of the surrounding rock with the grouting curtain;the high permeability water pressure difference can improve the permeability test accuracy;when the lateral opening area increases,the lateral permeability channel increases,leading to the reduction of the axial seepage rate.(2)It establishes the FLAC3 D seepage and excavation coupling model,and analyzes the truncation effect of grouting curtain belt on groundwater seepage from the aspects of displacement,stress and pore water pressure.The results show that,under the action of seepage and excavation unloading,the horizontal displacement of the slope presents the distribution characteristics of the drum belly along the elevation direction,and the maximum horizontal displacement increases with the increase of the excavation depth;the curtain setting weakens the transfer of the slope stress and protects the side slope body of the curtain body;and the seepage of groundwater along the karst fissure is effectively truncated in the periphery of the pit.(3)It establishes the dynamic analysis model considering the fluid solid coupling,and analyzes the dynamic response characteristics of grouting curtain body outside the rock slope of open pit under dynamic load.The results show that the elevation has a certain attenuation effect on the velocity and acceleration of the dynamic wave in the curtain body;at the low elevation of-36 m,the increase of the frequency of the dynamic wave of the vibration load will reduce the horizontal dynamic displacement of the measuring point in the curtain,increase the horizontal permanent displacement of the curtain and reduce the permanent displacement of the vertical,and the frequency of the dynamic load can reduce the effect of the self weight stress on the displacement.The higher the vibration frequency is,the smaller the permanent vertical stress changes of the curtain body after the vibration stops,the vertical stress of the curtain body at different heights shows the same fluctuation trend.(4)It establishes the dynamic analysis model considering the fluid solid coupling,and analyzes the dynamic response characteristics of grouting curtain body outside the rock slope of open pit under dynamic load.The results show that the elevation has a certain attenuation effect on the velocity and acceleration of the dynamic wave in the curtain body;at the low elevation of-36 m,the increase of the frequency of the dynamic wave of the vibration load will reduce the horizontal dynamic displacement of the measuring point in the curtain,increase the horizontal permanent displacement of the curtain and reduce the permanent displacement of the vertical,and the frequency of the dynamic load can reduce the effect of the self weight stress on the displacement.The higher the vibration frequency is,the smaller the permanent vertical stress changes of the curtain body after the vibration stops,the vertical stress of the curtain body at different heights shows the same fluctuation trend.