Roof Instability Mechanism And Control Technology Of Deep Gently Inclined Broken Gold Deposit

This paper takes Xinhui Gold Mine as the engineering background,and horizontal cut and fill mining method as the research object.It aims to reveal the stability characteristics of the surrounding rock of the stope with the deep gently inclined broken ore body filling method,and comprehensively adopts indoor mechanical tests,Theoretical derivation and numerical analysis and other technical means,focusing on the damage constitutive relationship and damage evolution characteristics of deep jointed rock mass,the stability classification of deep broken surrounding rock,roof instability mechanism,the anchoring mechanism of the cable on the broken roof and the calculation of anchoring capacity,the deformation and plastic zone evolution law of the surrounding rock of the site,and the selection of the mining method with horizontal cut and fill mining method.(1)Through laboratory mechanical tests,the basic mechanical parameters of the deep rock mass and the original rock stress of Xinhui Gold Mine were obtained;based on the theory of damage mechanics and the principle of strain equivalence,the concepts of initial joint damage,load damage and total damage were introduced to construct the damage constitutive model of jointed rock mass;based on the constructed damage evolution equation,the damage evolution characteristics of jointed rock mass are analyzed.(2)Based on the fractal theory of rock mass,the fractal dimension index of fractured rock mass is used to replace the rock mass quality index RQD and joint spacing index,and a new classification method(FT classification method)suitable for broken rock mass is innovatively formed,which makes up for the traditional RMR classification method of insufficient to determine the RQD and joint spacing;with the help of the FT classification method,the stability of the rock mass in the 6 measurement areas of Xinhui Gold Mine is classified,and compared with the traditional RMR method,it is considered that the FT classification method is suitable for broken rock mass and results are more accurate.(3)The roof instability mechanism of the deep gently inclined broken orebody is revealed.By introducing traction,the internal mechanism of roof instability is clarified.The smaller the dip of the ore body,the denser the distribution of traction,the smaller the thickness of the broken zone,and the sparser the distribution of traction;the greater the inclination of the ore body,the smaller the thickness of the broken zone,the smaller the traction;the traction and the inclination of the ore body have a quadratic polynomial function relationship.It has a linear function relationship with the thickness of the fracture zone;the area of the plastic zone decreases with the increase of the inclination of the ore body,and the two have a linear function relationship.The area of the plastic zone increases as the thickness of the fracture zone increases,and the two are in a quadratic polynomial function relationship.The largest area of the stope displacement is in the hanging wall and roof contact area,the anchor support effect is not obvious,the anchor cable can significantly improve the broken roof deformation state.(4)Clarified the mechanism of the anchor cable supporting,established the anchoring mechanics model of broken roof anchor cable,revealed the mechanism of anchor cable pre-tightening force,established the relationship model between pre-tightening force and various influencing factors;defined the anchor cable capacity value;Using SPSS software to simplify the calculation formula of anchorage capacity and regression prediction.The errors of the prediction results are all within 15%.It is considered that the regression model is reasonable and reliable.(5)The displacement of the stope surrounding rock increases with the increase of the stope width,stope height,joint size,joint density,buried depth and excavation interval;the stope surrounding rock displacement has a quadratic polynomial function with the width of the stope,joint size and joint density.Having a linear function relationship with stope height,buried depth and excavation interval,and has no obvious function relationship with joint tendency and joint inclination angle;the order of each influencing factor on the surrounding rock displacement of the stope is both-sided excavation>joint density>stope width>buried depth>unilateral excavation>joint size>joint dip>joint inclination>stope height.The anchor cable have a significant effect on the displacement of the stope.The stope displacement is reduced with supporting spacing and row spacing and the supporting length of anchor cable has not obviously affect of the stope ground displacement.(6)Based on the set pair analysis theory,interval intuitionistic fuzzy entropy and the distance method of superior and inferior solutions,a set of multi-attribute evaluation models are established using game theory and grey relational degree theory;the subjective weight of each parameter index is comprehensively considered using game theory and objective weights;Using the grey relational theory,analyze the positional relationship and morphological difference between the scheme results and the optimal solution of the model under different preference conditions,and eliminate the influence of subjective factors on the evaluation results;Through SPA-IVIFE-TOPSIS comprehensive evaluation model,the optimal stoping scheme for Xinhui Gold Mine is determined.