Optimal selection method for mining scheme of broken ore body

Abstract

The invention relates to an optimal selection method of a broken ore body mining scheme, and belongs to the technical field of metallurgical mine mining methods. According to the technical scheme, on the basis of a rock mass quality evaluation result, an analytic hierarchy process is combined with a fuzzy comprehensive evaluation theory, a multi-factor judgment matrix comprehensively considering economic indexes, mining field pressure control indexes and technical indexes of all the schemes is constructed, comprehensive evaluation vector superiority B values of all the mining schemes are obtained through analysis and calculation, and the comprehensive evaluation vector superiority B values of all the mining schemes are obtained. A proper mining method is preferably selected; based on a numerical simulation method, stope parameters and a stoping sequence are further optimized; and an economic and reasonable mining scheme is put forward in combination with reality. The method has the advantages that the method is simple and easy to operate, optimization results fit objective reality, safe, efficient and economical mining of the broken ore body can be effectively guided, and the method has high engineering guiding significance.

Description

Technical Field

[0001] The present invention relates to a method for optimizing a mining plan for broken ore bodies, belonging to the technical field of mining methods in metallurgical mines. Background Art

[0002] The selection of a mining plan is a complex process that needs to consider various factors, including the geological conditions of the ore deposit, physical and mechanical properties, mining technical conditions, etc. It also needs to consider the requirements of environmental protection, annual production plan and safety production, as well as the maximization of economic benefits. Especially for broken ore bodies, there are mining problems such as easy collapse. The selection of the mining plan and reasonable stope structure parameters have always been difficult problems restricting the safe, efficient and economic production of mines. Therefore, exploring an optimization method for the safe and efficient mining plan of broken and difficult-to-mine ore bodies and proposing reasonable mining methods and stope parameters have important practical significance for ensuring the safe, efficient and economic extraction of broken and difficult-to-mine ore bodies.

[0003] From the mining experience of various types of broken metal underground ore deposits at home and abroad, in the existing technology, the mining of broken ore deposits mainly focuses on using reasonable mining methods and mining sequences. For example, in the western ore body of the Qianbish Copper Mine, the ground pressure is large and the ore and rock are broken. Two process optimizations have been carried out, and finally the downward drift reinforced concrete false roof paste filling mining method is determined for the deep ore body; in the Xiaoguanzhuang Iron Mine of Luzhong Mining, the ore and rock are broken and the ore deposit is buried deep. According to its difficult mining situation, the upward drift filling mining method is adopted; the occurrence of the deep and difficult-to-mine ore body in the Kangjiawan Mine is complex. When mining the unstable gently inclined and difficult-to-mine thin ore body, the vertical slicing filling mining method is optimized; Zhang Bao et al. designed a panel unloading mining plan of the downward large-size drift filling mining method based on panel unloading mining for the ground pressure hazards such as floor heave and side wall collapse existing in the mining of a deep broken copper ore deposit under high stress conditions. In addition, technological progress and the development of new methods have also provided more possibilities for the selection of mining methods. Li Guanbing et al. used the analytic hierarchy process to score the alternative mining plans for the deep ore body of the Xinhui Gold Mine considering various aspects such as safety, economy, resources and efficiency, and finally optimized the upward horizontal slicing filling mining method with pre-reinforcement of ore pillars; Wang Chao et al. optimized the mining method of the mine based on the fuzzy comprehensive evaluation theory, constructed a fuzzy relationship matrix between the evaluation set and the factor set, and obtained the comprehensive evaluation values of each plan. Zhang Juzheng et al. optimized the mining method of the gold deposit based on the multi-attribute decision-making method of Fuzzy-TOPSIS, and obtained the final superiority and inferiority order of four mining methods according to the degree of fitting. In terms of stope parameter optimization, the Mathew stability chart method and numerical simulation calculation are mainly used to optimize the stope height, width and length in order to achieve the safe and efficient mining of broken ore bodies.

[0004] Based on the above research, it shows that the current existing technologies mainly carry out relevant research around two systems: the optimization of mining methods and the optimization of stope structure parameters. The content between the two systems is relatively independent, without being organically integrated, and no complete set of optimization methods has been formed. In addition, there are fewer evaluation index factors in the fuzzy evaluation and optimization of mining methods in the existing technologies, and the ground pressure management factors of difficult-to-mine ore bodies are not considered. Therefore, it is very necessary to design an optimization method for the safe and efficient mining plan of broken difficult-to-mine ore bodies, propose a scientific, reasonable, complete and comprehensive mining plan, and ensure the safe, efficient and economic extraction of broken difficult-to-mine ore bodies. Summary of the Invention

[0005] The object of the present invention is to provide an optimization method for the mining plan of broken ore bodies. By based on the results of rock mass quality evaluation, using the analytic hierarchy process and combining with the fuzzy comprehensive evaluation theory, a multi-factor evaluation matrix considering various plans is constructed, which includes not only economic indicators (mining cost, recovery rate, dilution rate), but also technical and efficiency indicators (cutting ratio per thousand tons, large block rate, production capacity, plan applicability, implementation difficulty), and at the same time includes safety indicators such as ground pressure control in the stope for difficult-to-mine ore bodies (ground pressure management difficulty, influence degree of blasting on stope stability). The evaluation model is more in line with the actual situation, and the optimization result is more objective. For the optimized plan, numerical simulation optimization research on stope parameters and stoping sequence is carried out, and the mining parameters such as stope height, width and length and stoping sequence are further optimized. It is simple and easy to operate, the optimization result is in line with the objective reality, and it can effectively guide the safe, efficient and economic mining of broken ore bodies, with strong engineering guiding significance, and effectively solves the above problems existing in the background technology.

[0006] The technical solution of the present invention is: an optimization method for the mining plan of broken ore bodies, comprising the following steps:

[0007] S1. Preliminary selection of mining methods, and preliminarily select mining plans;

[0008] S2. Construct a multi-factor evaluation matrix, use the analytic hierarchy process and combine with the fuzzy comprehensive evaluation theory to construct a multi-factor judgment matrix considering the economic indicators, ground pressure control indicators and technical indicators of each plan, and conduct consistency test; through comprehensive analysis of the weight matrices at all levels, obtain the total weight matrix and the hierarchical ranking list;

[0009] S3. Obtain the superiority B value of the comprehensive evaluation vector of each mining plan, and optimize the mining plan;

[0010] S4. Optimization of stope parameters and stoping sequence, according to the results of rock mass quality evaluation and the selected mining plan, combined with the optimized mining plan and stope parameter suggestions, use the numerical simulation method to further optimize the mining parameters such as stope length, width and height, and propose a reasonable mining plan.

[0011] In the step S1, based on the results of rock mass quality evaluation and combined with the requirements of the annual production plan, initially select 3 - 4 mining schemes, conduct technical and economic index descriptions and comparative analyses, and obtain the comparison table of technical and economic indexes for each scheme.

[0012] In the step S2, the economic indexes include mining cost, recovery rate, and dilution rate; the stope ground pressure control indexes include the difficulty of ground pressure management and the influence degree of blasting on the stability of the stope; the technical indexes include the mining and cutting ratio per thousand tons, large block rate, production capacity, scheme applicability, and implementation difficulty.

[0013] The economic indexes, stope ground pressure control indexes, and technical indexes are respectively defined as the first - level indexes P 1 , P 2 and P 3 , and the secondary evaluation indexes are: mining cost P 11 , comprehensive recovery rate P 12 , dilution rate P 13 , difficulty of ground pressure management P 21 , influence degree of blasting on the stability of the stope P 22 , mining and cutting ratio per thousand tons P 31 , scheme applicability P 32 , large block rate P 33 , implementation difficulty P 34 and production capacity P 35 ; Based on the analytic hierarchy process, construct the weight vector matrix O - P of the first - level evaluation indexes, and construct the weight matrices P 1 -P 1j , P 2 -P 2j and P3 - P 3j .

[0014] In the step S2, conduct a consistency test on the multi - factor judgment matrix. When the consistency coefficient CR < 0.1, it is considered that the optimal result obtained from the multi - factor judgment matrix meets the conditions; otherwise, it is considered not to meet the conditions, and the matrix needs to be adjusted again.

[0015] In the step S3, based on the membership function method of profitability and consumption quantitative indexes, for the six quantitative indexes, that is, the indexes evaluated by numerical values: mining cost P 11 , comprehensive recovery rate P 12 , dilution rate P 13 , mining and cutting ratio per thousand tons P 31 , large block rate P 33 and production capacity P 35 , conduct an analysis and list the quantitative index vector matrix R 1-6 as follows:

[0016]

[0017] After normalizing the non - quantitative indicators and combining them with the above matrix, the total fuzzy matrix R is obtained. Then, the superiority B value of the comprehensive evaluation vector is calculated according to the following formula:

[0018]

[0019] In the formula, B is the superiority index of the comprehensive evaluation vector; W is the weight of each evaluation index; r is the membership degree of each evaluation index.

[0020] In step S4, displacement comparison analysis, stress comparison analysis, shear stress comparison analysis and plastic zone comparison analysis are carried out under two cases of stope height of 60m and 30m, four cases of stope length of 50 - 60m and stope widths of 15m, 18m, 21m and 24m, so as to further determine the reasonable mining parameters of stope length, width and height;

[0021] Under two cases of stope height of 60m and 30m, three schemes of "mining one out of every two", "mining one out of every three" and "mining one out of every four" in the direction perpendicular to the ore body strike, and two schemes of "mining one out of every two" and "mining one out of every three" in the direction along the ore body strike are adopted. Comparative analysis of each scheme is carried out, mainly including: vertical - strike z - direction displacement comparison analysis, along - strike z - direction displacement comparison analysis, vertical - strike y - direction displacement comparison analysis, along - strike x - direction displacement comparison analysis, vertical - strike y - direction stress comparison analysis, vertical - strike z - direction stress comparison analysis, vertical - strike plastic zone comparison analysis and along - strike plastic zone comparison analysis. Then, z - direction displacement comparison analysis of each scheme is carried out, and a comparison diagram of stope z - direction vertical displacement of each scheme is drawn; further, comparison analysis of the inter - pillar y - direction horizontal displacement and inter - pillar z - direction stress between each scheme is carried out, and a comparison diagram of inter - pillar y - direction horizontal displacement of each scheme and a comparison curve diagram of inter - pillar stress are drawn, and finally a reasonable stoping sequence is determined;

[0022] Based on the stope parameters and the optimization results of the stoping sequence, a reasonable mining plan is proposed.

[0023] The displacement comparison analysis includes roof vertical displacement comparison analysis and side - wall horizontal displacement comparison analysis; the stress comparison analysis includes roof vertical compressive stress comparison analysis, side - wall horizontal compressive stress comparison analysis and side - wall horizontal tensile stress comparison analysis; the shear stress comparison analysis includes roof shear stress comparison analysis and side - wall shear stress comparison analysis; the plastic zone comparison analysis includes roof plastic zone comparison analysis and side - wall plastic zone comparison analysis.

[0024] The beneficial effects of the present invention are as follows: Based on the results of rock mass quality evaluation, the analytic hierarchy process is used, combined with the fuzzy comprehensive evaluation theory, to construct a multi-factor evaluation matrix that comprehensively considers various schemes, including not only economic indicators (mining cost, recovery rate, dilution rate), but also technical and efficiency indicators (development ratio per thousand tons, large block rate, production capacity, scheme applicability, implementation difficulty), and at the same time includes safety indicators such as ground pressure control in the stope for difficult-to-mine ore bodies (ground pressure management difficulty, influence degree of blasting on stope stability). The evaluation model is more in line with the actual situation, and the optimization results are more objective. For the optimized scheme, numerical simulation optimization research on stope parameters and mining sequence is carried out, further optimizing mining parameters such as stope height, width and length and the mining sequence. It is simple and easy to operate, the optimization results are in line with the objective reality, and it can effectively guide the safe, efficient and economic mining of broken ore bodies, with strong engineering guiding significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the flow chart of the present invention;

[0026] Figure 2 is the maximum displacement at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0027] Figure 3 is the displacement nephogram (w = 18m) at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0028] Figure 4 is the distribution of tensile and compressive stresses of rock mass at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0029] Figure 5 is the stress distribution nephogram (w = 18m) at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0030] Figure 6 is the shear stress distribution at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0031] Figure 7 is the shear stress nephogram (w = 18m) at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0032] Figure 8 is the plastic zone nephogram (w = 18m) at different stope widths when the stope height is 60m in the embodiment of the present invention;

[0033] Figure 9 is the schematic diagram of the simulated mining sequence in the embodiment of the present invention;

[0034] Figure 10 is the maximum displacement nephogram of the roof with the change of height in Scheme 2 (vertical displacement nephogram in the z direction along the strike) in the embodiment of the present invention;

[0035] Figure 11 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (displacement nephogram in the z - direction along the strike);

[0036] Figure 12 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (displacement nephogram in the y - direction perpendicular to the strike);

[0037] Figure 13 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (displacement nephogram in the x - direction along the strike);

[0038] Figure 14 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (stress nephogram in the y - direction perpendicular to the strike);

[0039] Figure 15 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (stress nephogram in the z - direction perpendicular to the strike);

[0040] Figure 16 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (plastic zone perpendicular to the strike);

[0041] Figure 17 It is the maximum displacement nephogram of the roof with height change in Scheme 2 of the embodiments of the present invention (plastic zone along the strike);

[0042] Figure 18 It is the comparison diagram of the vertical displacement in the Z - direction of the stope for each scheme in the embodiments of the present invention (the height of the ore room is 30m);

[0043] Figure 19 It is the comparison diagram of the vertical displacement in the Z - direction of the stope for each scheme in the embodiments of the present invention (the height of the ore room is 60m);

[0044] Figure 20 It is the comparison diagram of the horizontal displacement in the Y - direction of the intermediate pillar for each scheme in the embodiments of the present invention (the height of the ore room is 30m);

[0045] Figure 21 It is the comparison diagram of the horizontal displacement in the Y - direction of the intermediate pillar for each scheme in the embodiments of the present invention (the height of the ore room is 60m);

[0046] Figure 22 It is the comparison curve graph of the compressive stress in the Z - direction of the intermediate pillar for each scheme in the embodiments of the present invention. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the invention implementation cases clearer, the following will, in combination with the attached drawings in the implementation cases, clearly and completely describe the technical solutions in the implementation cases of the present invention. Obviously, the described implementation cases are a small part of the implementation cases of the present invention, rather than all of them. Based on the implementation cases in the present invention, all other implementation cases obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0048] A preferred method for a broken orebody mining plan includes the following steps:

[0049] S1. Preliminary selection of mining methods, preliminarily select mining plans;

[0050] S2. Construct a multi-factor evaluation matrix, use the analytic hierarchy process, and in combination with the fuzzy comprehensive evaluation theory, construct a multi-factor judgment matrix that comprehensively considers the economic indicators, stope ground pressure control indicators and technical indicators of each plan, and conduct a consistency test; through comprehensive analysis of the weight matrices at all levels, obtain the total weight matrix and the hierarchical ranking list;

[0051] S3. Obtain the comprehensive evaluation vector superiority B value of each mining plan, and optimize the mining plan;

[0052] S4. Optimize the stope parameters and stoping sequence. According to the rock mass quality evaluation results and the selected mining plan, in combination with the optimized mining plan and stope parameter suggestions, use the numerical simulation method to further optimize the stope length, width and height mining parameters, and propose a reasonable mining plan.

[0053] In step S1, based on the rock mass quality evaluation results and in combination with the annual production plan requirements, initially select 3 to 4 mining plans, conduct a description and comparative analysis of the technical and economic indicators, and obtain a comparison table of the technical and economic indicators of each plan.

[0054] In step S2, the economic indicators include mining cost, recovery rate and dilution rate; the stope ground pressure control indicators include the difficulty of ground pressure management and the impact degree of blasting on the stope stability; the technical indicators include the mining and cutting ratio per thousand tons, large block rate, production capacity, plan applicability and implementation difficulty.

[0055] The economic indicators, stope ground pressure control indicators and technical indicators are respectively defined as the first-level indicators P 1 、P 2 and P 3 , and the secondary evaluation indicators are: mining cost P 11 、comprehensive recovery rate P 12 、dilution rate P 13 、difficulty of ground pressure management P 21 、impact degree of blasting on the stope stability P 22 、mining and cutting ratio per thousand tons P 31, Solution Adaptability P 32 , Large Block Ratio P 33 , Difficulty of Implementation P 34 and Production Capacity P 35 ; Based on the analytic hierarchy process, construct the weight vector matrix O-P of the first-level evaluation indicators and the weight matrix P 1 -P 1j , P 2 -P 2j and P 3 -P 3j ;

[0056] In the said step S2, conduct a consistency test on the multi-factor judgment matrix. When the consistency coefficient CR < 0.1, it is considered that the optimal result obtained from the multi-factor judgment matrix meets the conditions; otherwise, it is considered not to meet the conditions and the matrix needs to be adjusted again.

[0057] In the said step S3, based on the membership function method of profitability and consumability quantitative indicators, for the six quantitative indicators, that is, the indicators evaluated by numerical values: mining cost P 11 , Comprehensive Recovery Rate P 12 , Dilution Rate P 13 , Mining and Development Ratio per 1000 Tons P 31 , Large Block Ratio P 33 and Production Capacity P 35 , conduct an analysis and list the quantitative indicator vector matrix R 1-6 as follows:

[0058]

[0059] After normalizing the non-quantitative indicators and combining with the above matrix, obtain the total fuzzy matrix R, and then calculate the superiority B value of the comprehensive evaluation vector according to the following formula:

[0060]

[0061] In the formula, B is the superiority index of the comprehensive evaluation vector; W is the weight of each evaluation index; r is the membership degree of each evaluation index.

[0062] In the said step S4, conduct displacement comparison analysis, stress comparison analysis, shear stress comparison analysis and plastic zone comparison analysis for two cases where the stope height is 60m and 30m respectively, and four cases where the stope length is 50 - 60m and the stope widths are 15m, 18m, 21m and 24m respectively, and further determine the reasonable stope length, width and height mining parameters;

[0063] For two cases where the stope height is 60m and 30m respectively, three schemes of "mining every other one", "mining every other two" and "mining every other three" are adopted in the direction perpendicular to the orebody strike, and two schemes of "mining every other one" and "mining every other two" are adopted in the direction along the orebody strike. Comparative analysis of each scheme is carried out, mainly including: comparative analysis of z-direction displacement perpendicular to the strike, comparative analysis of z-direction displacement along the strike, comparative analysis of y-direction displacement perpendicular to the strike, comparative analysis of x-direction displacement along the strike, comparative analysis of y-direction stress perpendicular to the strike, comparative analysis of z-direction stress perpendicular to the strike, comparative analysis of plastic zone perpendicular to the strike and comparative analysis of plastic zone along the strike. Then, comparative analysis of Z-direction displacement of each scheme is carried out, and a comparative diagram of Z-direction vertical displacement of each stope is drawn; then, comparative analysis of the Y-direction horizontal displacement and Z-direction stress of the intermediate pillars between each scheme is carried out, and a comparative diagram of the Y-direction horizontal displacement of the intermediate pillars and a comparative curve diagram of the stress of the intermediate pillars are drawn, and finally a reasonable stoping sequence is determined.

[0064] Based on the stope parameters and the optimized results of the stoping sequence, a reasonable mining scheme is proposed.

[0065] The displacement comparative analysis includes the comparative analysis of the vertical displacement of the roof and the comparative analysis of the horizontal displacement of the side wall; the stress comparative analysis includes the comparative analysis of the vertical compressive stress of the roof, the comparative analysis of the horizontal compressive stress of the side wall and the comparative analysis of the horizontal tensile stress of the side wall; the shear stress comparative analysis includes the comparative analysis of the shear stress of the roof and the comparative analysis of the shear stress of the side wall; the plastic zone comparative analysis includes the comparative analysis of the plastic zone of the roof and the comparative analysis of the plastic zone of the side wall.

[0066] In practical applications, the present invention includes the following steps:

[0067] The first step is the preliminary selection of the mining method. Based on the results of the rock mass quality evaluation and combined with the requirements of the annual production plan, 3-4 mining schemes are initially selected, the technical and economic indexes are described and compared, and a comparison table of the technical and economic indexes of each scheme is obtained.

[0068] The second step is to construct a multi-factor evaluation matrix. Using the analytic hierarchy process and combining the fuzzy comprehensive evaluation theory, a judgment matrix considering multiple factors such as the economic indexes (mining cost, recovery rate, dilution rate), stope ground pressure control (difficulty of ground pressure management, influence degree of blasting on stope stability) and technical indexes (cutting ratio per thousand tons, large block rate, production capacity, scheme applicability, implementation difficulty) of each scheme is constructed; and consistency test is carried out; through comprehensive analysis of the weight matrices at all levels, the total weight matrix and the hierarchical ranking list are obtained.

[0069] 1) Define the economic indicators, stope ground pressure control, and technical indicators as the first-level indicators P1, P2, and P3, respectively. The second-level evaluation indicators are: mining cost P11, comprehensive recovery rate P12, dilution rate P13, ground pressure management difficulty P21, impact degree of blasting on stope stability P22, excavation ratio per thousand tons P31, scheme adaptability P32, large block rate P33, implementation difficulty P34, and production capacity P35. Based on the analytic hierarchy process, construct the weight vector matrix O-P of the first-level evaluation indicators (for example, the matrix value corresponding to P1P3 is 2, indicating that the importance of P1 is 2 times that of P3).

[0070] Matrix O-P

[0071] O-P <![CDATA[P 1 > <![CDATA[P 2 > <![CDATA[P 3 > <![CDATA[P 1 > 1 1 2 <![CDATA[P 2 > 1 1 2 <![CDATA[P 3 > 1 / 2 1 / 2 1

[0072] Construct the weight matrix P of the second-level evaluation indicators 1 -P 1j 、P 2 -P 2j 、P 3 -P 3j 。

[0073] Matrix P 1 -P 1j

[0074] <![CDATA[P 1 > <![CDATA[P 11 > <![CDATA[P 12 > <![CDATA[P 13 > <![CDATA[P 11 > 1 1 / 2 1 / 4 <![CDATA[P 12 > 2 1 1 / 2 <![CDATA[P 13 > 4 2 1

[0075] Matrix P 2 -P 2j

[0076] <![CDATA[P 2 > <![CDATA[P 21 > <![CDATA[P 22 > <![CDATA[P 11 > 1 1 / 2 <![CDATA[P 12 > 2 1

[0077] Matrix P 3 -P 3j

[0078] <![CDATA[P 3 > <![CDATA[P 31 > <![CDATA[P 32 > <![CDATA[P 33 > <![CDATA[P 34 > <![CDATA[P 35 > <![CDATA[P 31 > 1 2 3 3 2 <![CDATA[P 32 > 1 / 2 1 3 3 4 <![CDATA[P 33 > 1 / 3 1 / 3 1 1 2 <![CDATA[P 34 > 1 / 3 1 / 3 1 1 2 <![CDATA[P 35 > 1 / 2 1 / 4 1 / 2 1 / 2 1

[0079] 2) To ensure the accuracy of the results, (based on the existing technology) conduct a consistency test on the above matrix. When the consistency coefficient CR < 0.1, it is considered that the optimal results obtained from the above matrix are relatively accurate. Otherwise, it is considered not to meet the requirements and the matrix needs to be adjusted again.

[0080] 3) Based on the analysis of the weight matrices at all levels above, obtain the total weight matrix W and the hierarchical ranking list.

[0081] In the third step, obtain the comprehensive evaluation superiority B value of each scheme and optimize the mining scheme. Through theoretical analysis and calculation, obtain the comprehensive evaluation vector (superiority) B values of 3 to 4 schemes, select the optimal mining scheme, and propose safety guarantee measures for the selected scheme.

[0082] Through on-site investigation and data collation, based on the membership function method of profitability and consumability quantitative indicators, six quantitative indicators in the above indicators (i.e., indicators evaluated by numerical values: mining cost P11, comprehensive recovery rate P12, dilution rate P13, heading ratio per thousand tons P31, large block rate P33, production capacity P35) are analyzed, and the quantitative indicator vector matrix R1-6 is listed as follows:

[0083]

[0084] After normalizing the non-quantitative indicators and combining them with the above matrix, the total fuzzy matrix R can be obtained. Then, the superiority B value of the comprehensive evaluation vector is calculated according to the following formula:

[0085]

[0086] In the formula, B is the superiority index of the comprehensive evaluation vector; W is the weight of each evaluation index; r is the membership degree of each evaluation index.

[0087] Fourth step, optimize the stope parameters and stoping sequence. Based on the numerical simulation method, further optimize the mining parameters such as stope length, width, and height.

[0088] According to the rock mass quality evaluation results and the selected mining method, combined with the optimized mining method and stope parameter suggestions, the displacement (vertical displacement of the roof, horizontal displacement of the side wall), stress (vertical compressive stress of the roof, horizontal compressive stress of the side wall, horizontal tensile stress of the side wall), shear stress (shear stress of the roof, shear stress of the side wall), and plastic zone (plastic zone of the roof, plastic zone of the side wall) are compared and analyzed under two cases of stope height of 60m and 30m, and four cases of stope length of 50-60m and stope width of 15m, 18m, 21m, and 24m by using the numerical simulation method, so as to further determine the reasonable mining parameters such as stope length, width, and height.

[0089] According to the results of rock mass quality evaluation and the selected mining method, combined with the recommended preferred mining method and stope parameters, numerical simulation method is used to conduct comparative analysis of various scenarios, including three scenarios of "mining every other one", "mining every other two", and "mining every other three" in the direction perpendicular to the ore body strike, with stope heights of 60m and 30m respectively, and two scenarios of "mining every other one" and "mining every other two" in the direction along the ore body strike. The main aspects of the comparative analysis include: comparative analysis of z-direction displacement perpendicular to the strike, comparative analysis of z-direction displacement along the strike, comparative analysis of y-direction displacement perpendicular to the strike, comparative analysis of x-direction displacement along the strike, comparative analysis of y-direction stress perpendicular to the strike, comparative analysis of z-direction stress perpendicular to the strike, comparative analysis of plastic zone perpendicular to the strike, and comparative analysis of plastic zone along the strike. Then, comparative analysis of z-direction displacement of each scenario is carried out, and a comparative diagram of z-direction vertical displacement of each stope scenario is drawn; further, comparative analysis of the y-direction horizontal displacement and z-direction stress of the intermediate pillars between each scenario is carried out, and a comparative diagram of y-direction horizontal displacement of the intermediate pillars between each scenario and a comparative curve diagram of the stress of the intermediate pillars are drawn; finally, a reasonable stoping sequence is determined.

[0090] Based on the stope parameters and the optimized results of the stoping sequence, a reasonable mining plan is proposed.

[0091] Example:

[0092] A certain iron mine in Hebei is a contact metasomatic skarn type magnetite deposit. The average thickness of the ore body is 64.67m, and the thick ore bodies above 35m account for 55.62%. Judging from the engineering exposure situation, the overall stability of the ore body is poor, and the ore body in the southern area is better than that in the northern area. It is necessary to conduct an optimization study on the mining plan for the ore body in the southern area.

[0093] (1) Preliminary selection of mining method. Based on the results of rock mass quality evaluation and combined with the requirements of the annual production plan, initially select 3 - 4 mining methods, and conduct technical and economic index description and comparative analysis.

[0094] For better optimization of the mining plan, rock mass quality evaluation was carried out on the ore body in the southern area of the mine. The results are shown in Table 1, indicating that the rock strength in this area is mainly grade IV and grade V. This also puts forward higher requirements for stope roof management and increases the difficulty of selecting the mining plan.

[0095] Table 1 Results of rock mass quality evaluation

[0096]

[0097] Based on the current mining technical conditions and the results of rock mass quality evaluation in the southern area of the mine, combined with the requirements of the annual production and operation plan, initially determine the following three mining methods: sublevel open stoping with subsequent backfilling mining method, VCR subsequent backfilling mining method, and large diameter longhole side caving sublevel open stoping with subsequent backfilling mining method. Comparative analysis is carried out on the comprehensive evaluation indexes of the three mining methods. The results are shown in Table 2, and a summary of the advantages and disadvantages of the three mining methods is shown in Table 3.

[0098] Comparison Table of Technical and Economic Indicators of Three Mining Methods

[0099]

[0100] Advantages and Disadvantages of Three Mining Methods

[0101]

[0102] (2) Construct a multi-factor evaluation matrix. Using the analytic hierarchy process and combining with the fuzzy comprehensive evaluation theory, construct a multi-factor judgment matrix that comprehensively considers the economic indicators (mining cost, recovery rate, dilution rate), stope ground pressure control (difficulty of ground pressure management, influence degree of blasting on stope stability), and technical indicators (development and cutting ratio per thousand tons, large block rate, production capacity, applicability of the plan, difficulty of implementation) of each plan; and conduct a consistency test; through comprehensive analysis of the weight matrices at all levels, obtain the total weight matrix and the hierarchical ranking list.

[0103] 1) Define the economic indicators, stope ground pressure control, and technical indicators as the first-level indicators P 1 、P 2 、P 3 , and the secondary evaluation indicators are: mining cost P 11 、comprehensive recovery rate P 12 、dilution rate P 13 、difficulty of ground pressure management P 21 、influence degree of blasting on stope stability P 22 、development and cutting ratio per thousand tons P 31 、applicability of the plan P 32 、large block rate P 33 、difficulty of implementation P 34 、production capacity P 35 . Based on the analytic hierarchy process, construct the weight vector matrix O-P of the first-level evaluation indicators (for example: the corresponding matrix value of P 1 P 3 is 2, indicating that the importance degree of P 1 is 2 times that of P 3 ).

[0104] Matrix O-P

[0105] O-P <![CDATA[P 1 > <![CDATA[P 2 > <![CDATA[P 3 > <![CDATA[P 1 > 1 1 2 <![CDATA[P 2 > 1 1 2 <![CDATA[P 3 > 1 / 2 1 / 2 1

[0106] Construct the weight matrix P 1 -P 1j 、P 2 -P 2j 、P 3 -P 3j .

[0107] Matrix P 1 -P1j

[0108] <![CDATA[P 1 > <![CDATA[P 11 > <![CDATA[P 12 > <![CDATA[P 13 > <![CDATA[P 11 > 1 1 / 2 1 / 4 <![CDATA[P 12 > 2 1 1 / 2 <![CDATA[P 13 > 4 2 1

[0109] Matrix P 2 -P 2j

[0110] <![CDATA[P 2 > <![CDATA[P 21 > <![CDATA[P 22 > <![CDATA[P 11 > 1 1 / 2 <![CDATA[P 12 > 2 1

[0111] Matrix P 3 -P 3j

[0112] <![CDATA[P 3 > <![CDATA[P 31 > <![CDATA[P 32 > <![CDATA[P 33 > <![CDATA[P 34 > <![CDATA[P 35 > <![CDATA[P 31 > 1 2 3 3 2 <![CDATA[P 32 > 1 / 2 1 3 3 4 <![CDATA[P 33 > 1 / 3 1 / 3 1 1 2 <![CDATA[P 34 > 1 / 3 1 / 3 1 1 2 <![CDATA[P 35 > 1 / 2 1 / 4 1 / 2 1 / 2 1

[0113] 2) To ensure the accuracy of the results, a consistency test is performed on the above matrix (based on the existing technology). When the consistency coefficient CR < 0.1, it is considered that the optimal results obtained from the above matrix are relatively accurate. Otherwise, it is considered not satisfied and the matrix needs to be adjusted again. The calculation and analysis results are as follows, and since all CR < 0.1, it is considered that the optimal results obtained from the above matrix are relatively accurate.

[0114] P 1 -P 1j :W 1 = [0.12, 0.27, 0.58] T , λ max1 = 3.36, CI = 0, RI = 0.52, C R1 = 0 < 0.1;

[0115] P 2 -P 2j :W 2 = [0.32, 0.66] T , λ max2 = 2.32, CI = 0, RI = 0, CR 2 = 0 < 0.1;

[0116] P 3 -P 3j :W 3 = [0.13, 0.25, 0.37, 0.21, 0.15] T , λ max3 = 5.247, CI = 0.002, RI = 1.12, CR = 0.0023 < 0.1.

[0117] 3) Based on the above analysis of the weight matrices at all levels, the total weight matrix W and the hierarchical sorting list are obtained as follows:

[0118] W = (0.055 0.231 0.286 0.115 0.018 0.024 0.036 0.067 0.033 0.135)

[0119] Hierarchical sorted list

[0120]

[0121] (3) Obtain the comprehensive evaluation vector superiority B value of each plan and optimize the mining plan. Through theoretical analysis and calculation, obtain the comprehensive evaluation vector superiority B value of 3 to 4 plans, optimize the optimal mining plan, and propose safety guarantee measures for the selected plan.

[0122] Through on-site investigation and data collation, based on the membership function method of profitability and consumption quantitative indicators, analyze the six quantitative indicators in the said indicators (that is, the indicators evaluated by numerical values: mining cost P 11 , comprehensive recovery rate P 12 , dilution rate P 13 , cutting ratio per thousand tons P 31 , large block rate P 33 , production capacity P 35 ), list the quantitative index vector matrix R 1-6 as follows:

[0123]

[0124] After normalizing the non-quantitative indicators and combining them with the above matrix, the total fuzzy matrix R is obtained:

[0125]

[0126] Calculate the comprehensive evaluation vector superiority B value according to the following formula, where B is the comprehensive evaluation vector superiority index; W is the weight of each evaluation index; r is the membership degree of each evaluation index.

[0127]

[0128] Finally, the comprehensive evaluation vectors under different mining methods are obtained as:

[0129] B = WR = (0.80 0.89 0.91)

[0130] Based on the above evaluations, it can be seen that: the superiority of the sublevel open stoping with subsequent filling mining method is 80%, the superiority of the VCR with subsequent filling mining method is 89%, and the superiority of the large-diameter longhole sidewise caving with subsequent filling mining method is 91%. It is recommended to select the large-diameter longhole sidewise caving with subsequent filling mining method as the main mining method for the ore body in the southern area of this mine, and at the same time strengthen the pre-control roof management during the mining process.

[0131] (4) Optimization of stope parameters and stoping sequence. Based on numerical simulation methods, further optimize the mining parameters such as stope length, width, and height.

[0132] 4.1 According to the rock mass quality evaluation results and the selected mining method, combined with the preferred mining method and stope parameter suggestions, use numerical simulation methods to conduct a comparative analysis of displacements (vertical displacement of the roof, horizontal displacement of the side wall), stresses (vertical compressive stress of the roof, horizontal compressive stress of the side wall, horizontal tensile stress of the side wall), shear stresses (shear stress of the roof, shear stress of the side wall), and plastic zones (plastic zone of the roof, plastic zone of the side wall) under two cases of stope heights of 60m and 30m, and four cases of stope lengths of 50 - 60m and stope widths of 15m, 18m, 21m, and 24m, respectively, to further determine reasonable mining parameters such as stope length, width, and height.

[0133] 1) Simulation scheme. A total of 8 optimization schemes were developed, and the numerical simulation model parameters were assigned according to the mechanical parameters in the rock mass quality evaluation report.

[0134] Simulation scheme

[0135] Scheme Stope width Stope height Stope length Scheme Stope width Stope height Stope length One 15m 60m 60m Five 15m 30m 60m Two 18m 60m 60m Six 18m 30m 60m Three 21m 60m 60m Seven 21m 30m 60m Four 24m 60m 60m Eight 24m 30m 60m

[0136] 2) Optimal analysis of stope width when the stope height is 60m.

[0137] (1) First, conduct displacement analysis. Figure 2 is the maximum mining displacement under different stope widths when the stope height is 60m, which includes the maximum vertical displacement of the roof and the maximum horizontal displacement of the side wall. From Figure 2 it can be seen that when the stope height is 60m, as the mining width increases, the increment of roof displacement is relatively large. When the mining width is 15m, the maximum vertical displacement of the rock mass is 46.91mm, which is less than the rock mass displacement stability criterion of 50mm, so the rock mass remains stable after mining. When the mining width increases to 18m, the maximum vertical displacement of the ore body after excavation can reach 54.24mm, exceeding the rock mass displacement stability criterion of 50mm but less than the rock limit movement displacement of 100mm. Therefore, after strict support after excavation, the rock mass can be kept in a relatively stable state. When the stope width continues to increase to 21m, the vertical displacement of the rock mass roof increases to 101.24mm, exceeding the rock movement limit criterion of 100mm, and the rock mass stability is extremely weak. When the stope width increases to 24m, the maximum vertical displacement of the rock mass roof reaches 137.63mm, indicating that the stope cannot maintain stability. In addition, as the stope width increases, the change in the horizontal displacement of the side wall does not exceed 1mm, indicating that the instability risk mainly comes from the vertical displacement of the roof, and the side wall stability is relatively high.

[0138] Figure 3It is the displacement nephogram of each stope width when the stope height is 60m (due to space limitations, only the displacement nephogram of the stope with a width of 18m is listed here). It can be seen that when the mining widths are 15m and 18m, the vertical displacement of the roof mainly distributes in the center, and the maximum vertical displacement of the rock mass is 46.91mm and 54.24mm. After strict support, the ore body can remain stable. When the mining width increases to 21m and 24m, the stress distribution at the top of the stope gradually concentrates, and the roof cannot remain stable. At this time, the vertical displacement amounts are 101.24mm and 137.63mm. For the horizontal displacement of the side wall, when the width increases, the stress distribution in the stope is basically the same, without significant changes.

[0139] (2) Secondly, stress analysis is carried out. Figure 4 It is the tensile and compressive stress distribution of different stope widths when the stope height is 60m. From Figure 4 it can be seen that there is only compressive stress in the vertical stress of the roof, and its values are 12.52MPa, 12.72MPa, 14.66MPa and 19.40MPa respectively. Among them, when the width increases from 18m to 21m, the increasing trend of the roof compressive stress becomes larger, indicating that the exposed area of the roof is too large, the load is high, and there is a risk of roof caving. Therefore, it is recommended that the stope width should not exceed 18m. There are two types of tensile stress and compressive stress in the horizontal stress of the side wall. As the stope width increases, the compressive stress on the side wall of the stope first increases and then decreases, while the tensile stress first decreases, then increases and finally decreases again. This shows that when the ore body width is less than 18m, the stope can maintain stability through support. When it exceeds 18m, the stope has undergone instability failure, and its stress is redistributed and cannot maintain a stable state.

[0140] Figure 5 It is the stress distribution nephogram of different stope widths when the stope height is 60m (due to space limitations, only the stress nephogram of the stope with a width of 18m is listed here). It can be seen that the compressive stress mainly distributes at the roof position, while the tensile stress mainly distributes at the side wall position. As the stope width increases, the distribution range of the high compressive stress gradually concentrates from a dispersed area to a certain position. When the stope width reaches 21m, the rock mass is subjected to the strongest compressive stress, and stress concentration occurs, resulting in the caving instability of the stope and inability to maintain stability.

[0141] (3) Then, shear stress analysis is carried out. Figure 6 It is the shear stress distribution of different stope widths when the stope height is 60m. It can be seen that as the stope width increases, the shear stresses of the roof and side wall both show an increasing trend. When the stope width exceeds 18m, the increasing trend of the roof shear force increases. When the stope width is less than 18m, the influence of the shear effect in the stope is relatively low. When it is greater than 18m, the shear stress increases, which is easy to induce the shear slip of the side wall of the stope and cause the instability of the stope.

[0142] Figure 7Shear stress nephograms of the roof and side walls at different stope widths when the stope height is 60 m (due to space limitations, only the shear stress nephogram of the stope with a width of 18 m is listed here). It can be seen that as the stope width increases, the shear distribution area of the roof gradually increases. Among them, when the stope width increases from 18 m to 21 m, the coverage rate of the shear area increases significantly, indicating that the ore body has become unstable and damaged due to shear action at this time; when the stope width reaches 21 m, the shear area of the side wall is relatively small, mainly concentrated on the roof. After exceeding 21 m, serious shear failure occurs on the side wall, and the ore body will collapse due to shear action.

[0143] (4) Finally, a comparative analysis of the plastic zones is carried out. Figure 8 Plastic zones of the roof and side walls at different stope widths when the stope height is 60 m (due to space limitations, only the plastic zone nephogram of the stope with a width of 18 m is listed here). It can be seen that when the stope width is between 15 m and 18 m, shear and tensile failures occur on the roof, and there is a trend of ongoing shear failure, but the failure area is small and it can maintain strong stability; when the stope width reaches 21 m, the degree of shear and tensile failure intensifies, and there is a relatively concentrated shear failure, and the stability of the stope cannot be maintained continuously. When the stope width reaches 24 m, the shear failure is extremely serious, and the ore body begins to collapse and become unstable in a large area; it can also be seen that the side wall is in a state of ongoing shear when the stope width is 15 m, and the stability of the stope needs to be maintained by support.

[0144] (5) A comprehensive analysis of the stope width optimization is carried out when the stope height is 60 m. Based on the above analysis, it can be known that when the stope height is 60 m, when the stope width is between 15 and 18 m, the rock mass movement displacement is between 50 mm and 100 mm. Based on combined support measures such as bolt-net-shotcrete and cable bolts, the stope can maintain stability and will not undergo instability failure. When the stope width exceeds 18 m, the rock movement amount exceeds 100 mm, the side wall of the stope will be severely sheared, and the roof will be damaged by strong compressive stress, etc., resulting in roof caving and side wall sliding instability, and it cannot maintain stability. Therefore, it is recommended that the stope width of 15 - 18 m be selected for mining operations, and at the same time, pre-control roof measures should be strengthened.

[0145] 3) When the stope height is 30 m, the optimal analysis of the stope width. Due to space limitations, the analysis process is not listed here, and only the analysis results are presented: when the stope height is 30 m, the stope width is 15 - 18 m, and the stope roof and sidewalls will maintain high stability. When the stope width is 18 - 21 m, shear and tensile failures occur in the stope sidewalls, and there is a certain risk of instability in the roof, but the rock displacement does not exceed the limit criterion of 100 mm. Therefore, after combined support such as bolting, shotcreting, and cable bolting, the ore body can be kept stable. When the stope width is 24 m, the rock displacement exceeds the limit criterion of 100 mm, large-area compressive stress appears in the roof, and severe shear and tensile effects occur in the sidewalls. At this time, the stope cannot be kept stable by support measures. Therefore, when the stope height is 30 m, it is recommended that the stope width be 18 - 21 m.

[0146] 4.2 According to the results of rock mass quality evaluation and the selected mining method, combined with the recommended optimal mining method and stope parameters, numerical simulation methods are used to conduct comparative analysis of three scenarios of "mining every other one", "mining every other two", and "mining every other three" in the direction perpendicular to the ore body strike, and two scenarios of "mining every other one" and "mining every other two" in the direction along the ore body strike, for two cases where the stope height is 60 m and 30 m respectively. The main aspects of the comparative analysis include: comparative analysis of z-direction displacement perpendicular to the strike, comparative analysis of z-direction displacement along the strike, comparative analysis of y-direction displacement perpendicular to the strike, comparative analysis of x-direction displacement along the strike, comparative analysis of y-direction stress perpendicular to the strike, comparative analysis of z-direction stress perpendicular to the strike, comparative analysis of plastic zone perpendicular to the strike, and comparative analysis of plastic zone along the strike. Then, comparative analysis of z-direction displacement of each scenario is carried out, and a comparative diagram of z-direction vertical displacement of the stope for each scenario is drawn; further, comparative analysis of the y-direction horizontal displacement and z-direction stress of the intermediate pillars between each scenario is carried out, and a comparative diagram of the y-direction horizontal displacement of the intermediate pillars and a comparative curve diagram of the stress of the intermediate pillars for each scenario are drawn. Based on the foregoing analysis results, a reasonable mining sequence is finally determined.

[0147] 1) Simulation scenarios

[0148] A total of 10 scenarios are designed, mainly optimizing the stope mining sequence in the direction along the ore body strike and the direction perpendicular to the ore body strike. Three scenarios of "mining every other one", "mining every other two", and "mining every other three" are designed in the direction perpendicular to the ore body strike, and two scenarios of "mining every other one" and "mining every other two" are designed in the direction along the ore body strike. The specific details of each scenario are shown in the table and Figure 9 . The parameters of the numerical simulation model are assigned according to the mechanical parameters in the rock mass quality evaluation report.

[0149] Numerical simulation scenarios for mining sequence

[0150] Stope height Scheme Scheme design 30m One "Mining every other one" in the strike direction and "mining every other one" in the direction perpendicular to the strike, that is, excavating stope 2#, 4#, 12#, and 14# respectively 60m Two "Mining every other one" in the strike direction and "mining every other one" in the direction perpendicular to the strike, that is, excavating stope 2#, 4#, 12#, and 14# respectively 30m Three "Mining every other two" in the strike direction and "mining every other one" in the direction perpendicular to the strike, that is, excavating stope 2#, 4#, 17#, and 19# respectively 60m Four "Mining every other two" in the strike direction and "mining every other one" in the direction perpendicular to the strike, that is, excavating stope 2#, 4#, 17#, and 19# respectively 30m Five "Mining every other one" in the strike direction and "mining every other two" in the direction perpendicular to the strike, that is, excavating stope 1#, 4#, 11#, and 14# respectively 60m Six "Mining every other one" in the strike direction and "mining every other two" in the direction perpendicular to the strike, that is, excavating stope 1#, 4#, 11#, and 14# respectively 30m Seven "Mining every other two" in the strike direction and "mining every other two" in the direction perpendicular to the strike, that is, excavating stope 1#, 4#, 16#, and 19# respectively 60m Eight "Mining every other two" in the strike direction and "mining every other two" in the direction perpendicular to the strike, that is, excavating stope 1#, 4#, 16#, and 19# respectively 30m Nine "Mining every other one" in the strike direction and "mining every other three" in the direction perpendicular to the strike, that is, excavating stope 1#, 5#, 11#, and 15# respectively 60m Ten "Mining every other one" in the strike direction and "mining every other three" in the direction perpendicular to the strike, that is, excavating stope 1#, 5#, 11#, and 15# respectively 30m Nine "Mining every other two" in the strike direction and "mining every other three" in the direction perpendicular to the strike, that is, excavating stope 1#, 5#, 16#, and 20# respectively 60m Ten "Mining every other two" in the strike direction and "mining every other three" in the direction perpendicular to the strike, that is, excavating stope 1#, 5#, 16#, and 20# respectively

[0151] 2) Calculation results and analysis of each scenario. Taking Scenario 2 as an example for analysis, due to space limitations, the analysis processes of other scenarios are not described.

[0152] After analysis, the z-direction displacement along the strike direction is slightly smaller than that in the direction perpendicular to the strike, but the displacements of the two sides (y) in the direction perpendicular to the strike are much larger than those of the two sides (x) along the strike direction, and the y-direction displacement of the stull between pillars perpendicular to the strike is greater than that of the two sides in the y-direction. Therefore, the z-direction displacement in the direction perpendicular to the strike, the y-direction displacement of the stull between pillars, stress, and plastic zone are selected as the judgment basis.

[0153] Scheme 2: The height of the ore room is 60m, with a spacing of 50m along the strike and 15m perpendicular to the strike. The calculation results are shown in Figures 10 to 17 . As can be seen from the figure, the maximum displacement of the roof is 80.998mm, the maximum horizontal displacement of the stull between pillars perpendicular to the strike is 67.398mm, and the maximum horizontal displacement along the strike is 23.076mm. The rock mass may become unstable. Considering the comprehensive stress nephogram and the distribution of the plastic zone, the horizontal tensile stress in the y-direction penetrates the stull between pillars, the distribution range of the tensile stress on the two sides is large, and most of the z-direction stress of the stull between pillars perpendicular to the strike is transferred. The ore room faces the risk of instability. Severe "X"-type shear failure occurs in the stull between pillars perpendicular to the strike, and severe shear slip occurs on the two sides. At the same time, shear failure occurs on the two sides of the ore room along the strike, and the distribution range of the plastic zone is large.

[0154] 3) Comparative analysis of the z-direction displacement of each scheme. The comparison of the vertical z-direction displacement of the stope for each scheme is as Figures 18 to 19 shown. It can be seen that when the height of the ore room is 30m, the z-direction displacement of the stope roof decreases with the increase of the spacing. When the distance between ore rooms along the ore body strike is 50m, the vertical z-direction displacement of the ore room roof increases with the increase of the distance perpendicular to the ore body strike, which are 77.859mm, 66.481mm, and 56.193mm respectively; when the distance between ore rooms along the ore body strike is 50m, the vertical z-direction displacement of the ore room roof increases with the increase of the distance perpendicular to the ore body strike, which are 68.435mm, 58.561mm, and 50.259mm respectively. The settlement and floor heave of the roof and floor gradually weaken, but when the spacing perpendicular to the ore body is less than 45m, the displacement is still large, and there is a risk of instability. By comparing the changes in displacement, when the height of the ore room is 30m, increasing the spacing perpendicular to the ore body has a better control effect on the displacement of the stope roof than increasing the spacing between ore rooms along the ore body strike.

[0155] When the height of the stope is 60m, the Z-direction displacement of the stope roof decreases with the increase of the spacing. When the distance along the ore body strike between stopes is 50m, the vertical Z-direction displacements of the stope roof are 80.998mm, 77.208mm, and 71.095mm respectively as the distance perpendicular to the ore body strike increases. When the distance along the ore body strike between stopes is 50m, the vertical Z-direction displacements of the stope roof are 73.862mm, 70.347mm, and 64.656mm respectively as the distance perpendicular to the ore body strike increases. The settlement of the roof and floor and the floor heave gradually weaken, but the displacement is still large, and there is a risk of instability. By comparing the changes in displacement, it can be seen that when the height of the stope is 60m, increasing the distance along the ore body strike has a better effect on controlling the displacement of the stope roof and floor than increasing the spacing perpendicular to the ore body strike.

[0156] 4) Comparative analysis of the Y-direction horizontal displacement and Z-direction stress of the intermediate pillars in each scheme. The comparison of the Y-direction horizontal displacement of the intermediate pillars in each scheme is as Figures 20 to 21 shown, and the comparison curve of the intermediate pillar stress is shown in Figure 22 . It can be seen that when the height of the stope is 30m, the horizontal displacement of the intermediate pillar first increases and then decreases with the increase of the spacing perpendicular to the strike, but the horizontal displacement at 15m is greater than that at 30m. The Z-direction compressive stress of the intermediate pillar increases with the increase of the spacing perpendicular to the strike and changes little with the increase of the spacing along the strike. Combining with the stress nephogram, it shows that when the intermediate pillar is 15m, the roof is unstable, and the compressive stress of the intermediate pillar roof is transferred in a large range, and the intermediate pillar bears less roof pressure. As the distance of the intermediate pillar increases to 30m, the roof is unstable, but the stress transfer weakens, and the intermediate pillar recovers part of its bearing capacity in the middle. The combined action of the compressive stress and horizontal tensile stress from the roof leads to an increase in the horizontal displacement. When the distance of the intermediate pillar increases to 45m, the intermediate pillar can stably bear the roof pressure, and the distribution range of the horizontal tensile stress decreases. The horizontal displacement of the intermediate pillar decreases with the increase of the spacing along the strike, but the decreasing rate is less than that perpendicular to the strike. The Z-direction compressive stress of the intermediate pillar changes little with the increase of the spacing along the strike.

[0157] When the stope height is 60m, the roof compressive stress is less than that when the height is 30m. The roof compressive stress transfers over a large range. As the vertical strike distance increases, the maximum compressive stress of the intermediate pillar increases, and the transfer of the roof compressive stress weakens. However, when the distance between the intermediate pillars increases to 45m, the maximum compressive stress of the intermediate pillar is 15MPa and 17MPa. The tensile stress value and distribution range gradually decrease. As the distance along the ore body strike increases, the stress slightly weakens but the change is not obvious. The horizontal stress in the Y direction of the stope first increases and then decreases with the increase of the vertical strike distance, but is greater than the initial value. When the intermediate pillar is 15m, the tensile stress is fully covered. When the intermediate pillar is 30m, the tensile stress shows an "X" shape distribution, and small-value compressive stress concentration areas are formed above and below, jointly resulting in an increase in the horizontal tensile stress. When the intermediate pillar is 45m, the tensile stress tends to be "X" shaped but is only distributed on both sides, posing a risk of instability. The horizontal displacement of the intermediate pillar in the stope is greater than that on both sides of the stope, and it increases with the increase of the horizontal displacement in the Y direction as the vertical distance between the stope rooms along the ore body strike increases. Increasing the distance along the ore body strike, the horizontal displacement of the intermediate pillar decreases to a certain extent, which is consistent with the change characteristics of the horizontal stress in the Y direction of the stope.

[0158] Based on the above analysis, when the stope height is 30m, increasing the vertical distance along the ore body strike has a better effect than increasing the distance along the ore body strike. This shows that reasonably increasing the Y-direction distance between the mined stope rooms and appropriately reducing the X-direction distance between the mined stope rooms can better control the roof displacement and reduce the early mining and cutting costs. From the comprehensive Z-direction displacement nephogram, when the Y-direction distance between the stope rooms is less than 45m, the roof stress transfers over a large range, the tensile stress increases, and the vertical and horizontal displacements of the stope are both large. Therefore, reasonable support measures need to be taken for the stope to ensure the stability of the stope. Considering from the economic perspective of the stope, when the vertical distance along the ore body strike between the stope rooms is 45m and the distance along the ore body strike is 50 or 100m, the stope can maintain good stability. When the stope height is 60m, increasing the distance along the ore body strike is better than increasing the distance perpendicular to the ore body strike, but the displacement of the stope is relatively large, and there is a risk of instability in the stope.

[0159] 5) Based on the above analysis results, the reasonable stoping sequence is finally determined. Considering the displacement, stress, plastic zone criterion and the conditions of numerical simulation (bare rock condition) comprehensively, it is recommended that when the stope height is 30m and 60m, the method of mining every other three in the vertical strike direction can be selected, and either mining every other one or mining every other two in the strike direction is acceptable. If mining every other one or mining every other two in the vertical strike direction is selected, the support of the stope roof must be strengthened.

[0160] 4.3 Based on the above analysis, a reasonable mining plan for the ore body in the southern area of the mine is proposed: Select the large-diameter long-hole sidewise caving sublevel backfilling mining method, with a stope height of 60m, a width of 18m, and a length not exceeding 50m. Mine every other one or mining every other two along the ore body strike, and mine every other one or mining every other two perpendicular to the ore body strike. At the same time, strengthen the support of the stope roof.

[0161] 4.4 On-site engineering application. In the area between Exploration Lines 2 and 3 in the southern region of the mine at the levels of -230 to -170 m, a 13#S4 experimental stope was selected to conduct experimental research on the large-diameter long-hole mining method with a mining height of 60 m. The stope is 60 m high, 50 m long, and 18 m wide, with an ore reserve of 134,000 t. A total of 123,000 t of ore has been extracted, and the recovery rate is 90.79%. The rock-drilling chamber was pre-controlled for roof support by adopting the combined support measures of bolt-net-shotcrete + long cable bolts. No caving occurred during the mining process, achieving safe, efficient, and economic mining. It can be popularized and applied in the southern region.

Claims

1. A method for optimizing a crushed ore body mining scheme, characterized in that The following steps are involved: S1. Preliminary selection of mining methods and mining plans; S2. Construct a multi-factor judgment matrix, use the analytic hierarchy process, and combine the fuzzy comprehensive evaluation theory to construct a multi-factor judgment matrix that comprehensively considers the economic indicators, ground pressure control indicators, and technical indicators of each scheme, and conduct consistency tests; comprehensively analyze the weight matrices at all levels to obtain the total weight matrix and hierarchical ranking list; S3, obtaining the superiority B value of the comprehensive evaluation vector of each mining scheme, and optimizing the mining scheme; S4. Optimization of stope parameters and mining sequence. Based on the rock mass quality evaluation results and the selected mining scheme, combined with the preferred mining scheme and stope parameter recommendations, a numerical simulation method is used to further optimize the stope length, width and height mining parameters, and a reasonable mining scheme is proposed.

2. The method for optimizing a broken ore body mining scheme according to claim 1, characterized in that: In step S1, based on the rock mass quality evaluation results and combined with the annual production plan requirements, 3 to 4 mining plans are preliminarily selected, and technical and economic index descriptions and comparative analyses are performed to obtain a technical and economic index comparison table for each plan.

3. The method for optimizing a broken ore body mining scheme according to claim 1, characterized in that: In step S2, the economic indicators include mining cost, recovery rate and depletion rate; the ground pressure control indicators include the difficulty of ground pressure management and the impact of blasting on the stability of the stope; Technical indicators include thousand-ton mining and cutting ratio, large block rate, production capacity, program applicability and implementation difficulty.

4. The method for optimizing a broken ore body mining scheme according to claim 3 is characterized in that: The economic indicators, ground pressure control indicators and technical indicators are defined as the first-level indicators P1, P2 and P3 respectively, and the second-level evaluation indicators are: mining cost P 11 , comprehensive recovery rate P 12 , depletion rate P 13 , Ground pressure management difficulty P 21 , the influence degree of blasting on the stability of the stope 22 , 1,000 tons of mining and cutting ratio P 31 、Scheme adaptability P 32 , large block rate P 33 , Difficulty of implementation 34 and production capacity P 35 ; Based on the hierarchical analysis method, the weight vector matrix OP of the first-level evaluation index is constructed, and the weight matrix P1-P of the second-level evaluation index is constructed. 1j 、P2-P 2j and P3-P 3j .

5. The method for optimizing a broken ore body mining scheme according to claim 1, characterized in that: In step S2, the multi-factor judgment matrix is ​​subjected to consistency check. When the consistency coefficient CR<0.1, it is considered that the optimal result obtained by the multi-factor judgment matrix meets the conditions; Otherwise, it is considered unsatisfactory and the matrix is ​​readjusted.

6. The method for optimizing a broken ore body mining scheme according to claim 4, characterized in that: In step S3, based on the membership function method of profitability and consumption quantitative indicators, six quantitative indicators, i.e. indicators evaluated by numerical values, are evaluated: mining cost P 11 , comprehensive recovery rate P 12 , depletion rate P 13 , 1,000 tons of mining and cutting ratio P 31 , large block rate P 33 and production capacity P 35 , analyze and list the quantitative indicator vector matrix R 1-6 as follows: After normalizing the non-quantitative indicators and combining them with the above matrix, the total fuzzy matrix R is obtained, and then the superiority value B of the comprehensive evaluation vector is calculated according to the following formula: Where B is the superiority index of the comprehensive evaluation vector; W is the weight of each evaluation index; r is the membership degree of each evaluation index.

7. The method for optimizing a broken ore body mining scheme according to claim 1, characterized in that: In step S4, displacement comparison analysis, stress comparison analysis, shear stress comparison analysis and plastic zone comparison analysis are performed for two cases where the stope height is 60m and 30m, the stope length is 50-60m, and the stope width is 15m, 18m, 21m and 24m, respectively, to further determine reasonable stope length, width and height mining parameters; Under the two cases of stope height of 60m and 30m respectively, three schemes of "mining every other one", "mining every other two" and "mining every other three" in the vertical ore body strike direction, and two schemes of "mining every other one" and "mining every other two" along the ore body strike direction, comparative analysis of various schemes is carried out, mainly including: comparative analysis of vertical strike z-direction displacement, comparative analysis of z-direction displacement along the strike, comparative analysis of vertical strike y-direction displacement, comparative analysis of x-direction displacement along the strike, comparative analysis of vertical strike y-direction stress, comparative analysis of vertical strike z-direction stress, comparative analysis of vertical strike plastic zone and comparative analysis of plastic zone along the strike, then comparative analysis of Z-direction displacement of various schemes is carried out, and a comparison chart of Z-direction vertical displacement of various schemes is drawn; then comparative analysis of Y-direction horizontal displacement of pillars and Z-direction stress of pillars of various schemes is carried out, and a comparison chart of Y-direction horizontal displacement of pillars and comparison curve of pillar stress of various schemes are drawn, and finally a reasonable mining sequence is determined; Based on the optimization results of stope parameters and mining sequence, a reasonable mining plan is proposed.

8. The method for optimizing a broken ore body mining scheme according to claim 7, characterized in that: The displacement comparison analysis includes the vertical displacement comparison analysis of the top plate and the horizontal displacement comparison analysis of the side walls; the stress comparison analysis includes the vertical compressive stress comparison analysis of the top plate, the horizontal compressive stress comparison analysis of the side walls and the horizontal tensile stress comparison analysis of the side walls; the shear stress comparison analysis includes the shear stress comparison analysis of the top plate and the shear stress comparison analysis of the side walls; the plastic zone comparison analysis includes the plastic zone comparison analysis of the top plate and the plastic zone comparison analysis of the side walls.

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