A study on site selection of coal mine emergency material reserve based on genetic algorithm

China’s industrial development can not be separated from the support of energy, especially coal resources. Coal production has been growing rapidly in response to the growing demand for coal in China. However, China’s coal mine safety management level is limited, the coal million ton mortality rate, the number of coal mine accidents and the number of coal mine accident fatalities are still very large, especially the number of major accidents and the proportion of major accidents and fatalities in recent years is getting higher and higher, which has caused a great deal of social concern, and China’s coal mine safety production situation still needs to be strengthened and improved [1–3]. Coal mine emergency supplies reserve belongs to an important part of coal mine safety management, is an important guarantee when emergency coal mine accidents occur, especially when dealing with major mining accidents, due to the coal mine emergency supplies are not in place and delayed the best time to rescue, thus causing major economic losses very casualties [4–6].

Due to the suddenness and severity of coal mine accidents, it brings important casualties and economic losses to the society and the country, but due to the factors of technology, management and self-recognition, coal mine accidents can not be avoided completely, so the aftermath management of coal mine accidents is very important to the coal mine safety management [7–9]. How to utilize the existing emergency rescue system and emergency rescue materials in the coal mine mine is important for the rescue and relief of coal mine emergencies, which is the key to the emergency rescue of mine disaster accidents [10–12]. According to statistics, in 2016, the number of coal production mines in China’s provinces and cities is 5747, the number is particularly large, but due to the economic conditions of the limitations of each mine can not be equipped with a full set of emergency rescue materials, so when the disaster occurs, it is necessary to coal mine emergency supplies reserve in the shortest possible time to provide emergency supplies. Therefore, the layout of coal mine emergency material reserve depot will affect the efficiency of mine accident rescue and relief to a great extent [13–16].

Genetic algorithm is a kind of search algorithm, by simulating biological evolution, using population search technology to carry out genetic operations on the current population, so that the population gradually evolves to contain or near-optimal solutions. Genetic algorithms have a very strong search and expansion ability, and can be combined with other algorithms according to modeling requirements to improve the operation effect [17–19]. Therefore, we can try to apply the genetic algorithm to the coal mine emergency reserve site selection problem, in order to better cope with and deal with the coal mine mine emergencies, improve the level of emergency rescue of coal mining enterprises, and minimize the losses caused by mining disasters [20–22].

2

Site Selection Methods

In this section, this paper designs a two-stage siting model to solve the siting problem of emergency stockpile depot, as shown in Fig. 1, which includes the following main contents: siting model, scheme screening, and scheme comparison.

2.1

Preliminary selection of emergency stockpile program

2.1.1

Model equations

In response to the emergency situation of sudden coal mine incident, the siting problem of coal mine emergency reserve is a multi-objective optimization problem, for the main objectives of siting, namely, the cost of siting, the time spent and the attractiveness of the reserve and the coal mine point, the establishment of this multi-objective optimization model can be described as: 1)

Minimize the total cost of emergency rescue

In order to ensure the economy, this paper divides the total cost into four parts, the first part is the cost of establishing the emergency reserve, the second part is the maintenance cost of the emergency reserve, the third part represents the cost of hiring personnel for the emergency reserve, and the fourth part represents the transportation cost from the emergency reserve to the coal mine point; the objective function 1 is set as the minimum of the sum of the total cost of the emergency reserve to reach the accident point of the coal mine as shown in equation (1): 1 $\min C = \sum_{j \subseteq J} K_{j} M_{j S} + \sum_{j \subseteq J} K_{j} M_{j H} + \sum_{j \subseteq J} K_{j} M_{j g} Y_{j} + \sum_{j \subseteq J} \sum_{i \subseteq I} D_{i j} M_{i j} A_{i j} M_{j D} (P_{i} - B_{i})$

Where: C is the sum of the costs for the emergency reserve to reach the accidental coal mine point; M_jS is the construction cost of reserve j; M_jH is the daily maintenance cost of reserve j; M_jg is the wage cost of a single staff member of reserve j; Y_j is the number of staff members needed for reserve j; D_ij is the distance between reserve j and coal mine point i; M_ij is the unit transportation cost between the reserve j and the coal mine site i; P_i is the demand for relief supplies at the coal mine site i; and B_i is the storage capacity of relief supplies at the coal mine site i;

2)

The shortest total time for emergency rescue arrival

When there are emergencies such as roof, fire, gas, etc. in the coal mine, whether the emergency rescue team can quickly arrive at the accidental coal mine point is directly related to the consequences of the accident. Determine the accidental coal mine point and carry out the transportation of rescue materials, the objective function 2 is set as the shortest sum of time for the emergency reserve to reach the accidental coal mine point, as shown in equation (2): 2 $\min T = \frac{\sum_{j \subseteq J} \sum_{i \subseteq I} D_{i j} A_{i j} K_{j} W_{i}}{V} + \frac{\sum_{j \subseteq J} (P_{i} - B_{i})}{Y_{R}}$

Where: T is the sum of the time for the emergency reserve to reach the accidental coal mine point; D_ij is the distance between the reserve j and the coal mine point i; P_i is the demand for rescue materials at the coal mine point i; B_i is the storage capacity of the rescue materials at the coal mine point i; Y_R is the total loading and unloading efficiency of the staff; A_ij is the decision variable, which specifically refers to whether or not the reserve j provides emergency rescue services to the coal mine point i. K_j is the decision variable, specifically whether the candidate depot j is selected as the reserve depot W_i for the coal mine point i risk weight.

3)

The total gravitational force between the emergency reserve bank and the coal mine point is maximized

The total gravitational force between the emergency reserve and the coal mine point reflects the interaction strength between them. The larger the total gravitational force, the stronger the correlation between the two, and the more obvious the role of the emergency reserve in responding to coal mine accidents. The objective function 3 is set to maximize the total gravitational force between the emergency reserve and the coal mine point, as shown in equation (3): 3 $\max F = \sum_{j \subseteq J} \sum_{i \subseteq I} (\frac{B_{j} * S_{i}}{B_{i} * D_{i j}})$

Where: F is the total gravitational force between the emergency supplies reserve and the coal mine site; B_i is the original storage capacity of rescue supplies at the coal mine site i; B_j is the storage capacity of rescue supplies at the reserve j; and S_i is the risk level rating of the coal mine site i.

2.1.2

Constraints

1)

Reserve bank quantity constraint

The number of reserve banks should be at a certain limit, as shown in equation (4): 4 $0 \leq C \sum_{j \subseteq J} K_{j} \leq C$

2)

Distance constraint between candidate reserve and coal mine

In order to ensure the time for the candidate reserve to reach the coal mine point, the distance between the candidate reserve and the coal mine is constrained as shown in equation (5): 5 $D_{i j} \leq R (\forall i \in I, \forall j \in J)$

3)

Limitation on the amount of materials stored in the reserve bank

In order to ensure the adequacy of rescue materials, the amount of materials stored in the reserve should be greater than the amount of materials required by the coal mine, as shown in equation (6): 6 $\sum_{j \subseteq J} \sum_{i \subseteq I} (P_{i} - B_{i}) A_{i j} \leq \sum_{j \subseteq J} K_{j} B_{j}$

4)

Only Candidate Bank j is selected as a reserve bank to support Coal Mine Point i, as shown in Equation (7): 7 $A_{i j} \leq K_{j} (\forall i \in I, \forall j \in J)$

5)

Decision variable, specifically whether candidate bank j is selected as a reserve bank, when K_j = 1, that is, candidate bank j is selected as a support reserve bank; when K_j = 0, that is, candidate bank j is not selected as a support reserve bank, as shown in equation (8): 8 $K_{j} = (0, 1) (\forall i \in I, \forall j \in J)$

6)

Decision variable, specifically, whether or not Reserve j provides emergency relief services to Coal Mine Point i. At A_ij = 1, that is, there is a support relationship between Reserve j and Coal Mine Point i; at A_ij = 0, that is, there is no support relationship between Reserve j and Coal Mine Point i; as shown in Equation (9): 9 $A_{i j} = (0, 1) (\forall i \in I, \forall j \in J)$

2.1.3

Parameterization

According to the Liaoning Provincial Development and Reform Commission Announcement (No. 1 of 2023), the study is conducted for 26 production coal mines and 4 construction coal mines, totaling 30 coal mine sites in Liaoning Province. Since the information of the past years is not available to check the demand of the coal mines, this paper invokes a random number to generate the demand of the material and the original material at the coal mine sites, and calculates the amount of the material that needs to be transported to the coal mines from the reserve depot in order to carry out the subsequent analysis and processing, which has been widely accepted and used in similar studies in the past literature. According to the document issued by the Ministry of Emergency Management of the People’s Republic of China, the average speed of emergency rescue vehicles is between 50km/h and 70km/h, so this paper integrates the road conditions, weather conditions and other factors to set the average speed of 60km/h; according to the “Disaster Relief Materials Reservoir Construction Standard Jianbiao 121-2009”, it is known that the net height of the emergency reserve depot should not be less than 6 meters, so this paper sets the depot height to 6 meters. In this paper, the height of the warehouse is set to 6 meters. According to the data of National Bureau of Statistics, the staff composition of the material reserve depot should be composed of 12-14 managers and 18-21 professionals, and a total of 30-35 staff members are needed, so this paper sets the number of staff members as 30. According to the “disaster relief supplies reserve warehouse various types of room area table” can be seen in the reserve warehouse warehouse area of 3985-6641 square meters, the production of auxiliary room area of 308 square meters, the management of the room area of 422495 square meters, accessory room area of 179-192 square meters, so the total area of the warehouse for the warehouse area, the production of auxiliary area, the management of the room area, the area of accessory room and the area of 5000-7800 square meters. Therefore, the total storage area is the sum of storage area, production support room area, management room area and subsidiary room area, which is 5000-7800 square meters, so the storage area is set as 7200 square meters. The storage capacity is 43,200 cubic meters when the storage area and reserve height are combined. The rest of the experimental data collection process is shown in Table 1.

Table 1.

Variables and sources

Variable Name	Description	Source	Numerical value
Warehousing Costs	Industrial Storage Costs in Liaoning Province	IOT Cloud Warehouse Digital Research Institute	1.092192 million yuan 7200m²
Storage building area	Area of Emergency Reserve Depot	Liaoning Reserve Materials Management Bureau Website	1.092192 million yuan 7200m²
Height of storage	Net height of the warehouse of the emergency stockpile	Relief Materials Reserve Bank Construction Standard Jianbiao 121-2009
Material storage capacity	Material storage capacity of the reserve depot	Relief Materials Reserve Bank Construction Standard Jianbiao 121-2009	6m
Employment	Number of staff required for a single reserve depot	National Bureau of Statistics	43200m³
Unit transportation cost	Unit transportation cost from reserve depot to coal mine	China Coal Information Network	30 people
Total loading and unloading efficiency	Total loading and unloading efficiency of staff at the reserve depot	Statistical Indicators of Loading and Unloading Work	2.832 thousand yuan / km / m³
Labor cost	Average wage cost per staff member	Liaoning Provincial Department of Human Resources and Social Security	750 cubic meters / hour
Average speed	Average speed of emergency response vehicles	Ministry of Emergency Management of the People’s Republic of China	0.7121 thousand yuan

2.1.4

Solution algorithms

Commonly used multi-objective optimization algorithms mainly include genetic algorithms, evolutionary algorithms, simulated annealing algorithms, particle swarm algorithms, and so on. In this study, we chose NSGA-II for testing. NSGA-II is an effective algorithm for solving the global optimal solution of multi-objective optimization problems. Using Python programming software to run the genetic algorithm, it can be realized to solve the multi-objective model. The steps for solving the NSGA-II are as follows: 1)

Initialization: perform parameter setting and randomly generate the initialized population P(t).

2)

Evaluation: Evaluate the fitness of each initialized population P(t) and judge its superiority or inferiority.

3)

Selection: according to the fitness value of each individual, select a part of individuals as the population of the next generation in some way.

4)

Mutation: perform mutation operations on some individuals to increase the diversity of the population.

5)

Crossover: perform crossover operation on some individuals to produce new individuals.

Repeat steps 2-5 until the stopping condition is satisfied. The process is shown in Figure 2.

2.2

Emergency Stockpile Program Screening

Compared with the traditional entropy value method, the entropy value-TOPSIS method combines the two methods of entropy value method and TOPSIS, which can make better use of the information, reduce the subjectivity in the process of determining the weights, and can be ranked according to the degree of proximity of the evaluation object to the idealized target to improve the accuracy of the evaluation, and it is a kind of efficient multi-objective decision-making method. The method consists of the following steps. 1)

Construct the standardization matrix. Where x_ij is the value of the j rd indicator of the i nd demand point. The matrix is 10 $x_{i j} = [[\begin{matrix} x_{11} & \dots & x_{1 n} \\ ⋮ & ⋱ & ⋮ \\ x_{m 1} & \dots & x_{m n} \end{matrix}]]$

2)

Data standardization. For positive and negative indicators, the treatment is as follows: 11 $b_{P o s i t i v e i j} = \frac{x_{i j} - \min (x_{j})}{\max (x_{j}) - \min (x_{j})}$ 12 $b_{N e g a t i v e i j} = \frac{\max (x_{j}) - x_{i j}}{\max (x_{j}) - \min (x_{j})}$

3)

Calculate the weight of the indicator. 13 $p_{i j} = \frac{b_{i j}}{\sum_{i = 1}^{m} y_{i j}}$

4)

Calculate the entropy value of the indicator. 14 $e_{j} = \frac{1}{\ln n} \sum_{i = 1}^{n} p_{i j} \ln p_{i j}$

5)

Calculate the degree of variability of the indicator. 15 $g_{j} = 1 - e_{j}$

6)

Calculation of indicator weights. 16 $w_{j} = \frac{g_{j}}{\sum_{i = 1}^{m} g_{j}}$

7)

Calculate the weighted norm matrix. 17 $z_{i j} = y_{i j} w_{j}$

8)

Determine the positive and negative ideal solutions and the Euclidean distance. 18 $z_{j}^{+} = \max (z_{1 j}, z_{2 j}, z_{3 j}, \dots, z_{n j})$ 19 $z_{j}^{-} = \min (z_{1 j}, z_{2 j}, z_{3 j}, \dots, z_{n j})$

The Euclidean distance formula is derived from the resulting positive and negative ideal solutions as: 20 $d_{i}^{+} = \sqrt{{\sum_{j = 1}^{n} (c_{i j} - c_{j}^{+})}^{2}}$ 21 $d_{i}^{-} = \sqrt{{\sum_{j = 1}^{n} (c_{i j} - c_{j}^{-})}^{2}}$

9)

Calculate the proximity closeness of each scenario: 22 $c_{i} = \frac{z_{j}^{-}}{z_{j}^{+} + z_{j}^{-}}$

10)

Rank the schemes based on relative closeness and select the optimal scheme.

3

Example analysis

Liaoning Province, as an important province in the northeast region, has a strong industrial base and technical strength, and is an important industrial base in China, which provides the necessary technical support and talent guarantee for the establishment of a coal mine emergency reserve. Due to the large amount of coal mining, many accidents have occurred in coal mines in the region. Liaoning Province is located in the northeast of China and is adjacent to several provinces, which have certain advantages in terms of geographic location and are conducive to the deployment and transportation of emergency supplies. In addition, with the accelerated revitalization of the new round of old industrial bases in Liaoning Province, it provides policy support and historical opportunities for the establishment of coal mine emergency reserves. It is worth noting that despite the huge consumption of coal in Liaoning Province, the self-sufficiency rate of the province is decreasing, and a large amount of coal needs to be imported from outside. Therefore, Liaoning Province is selected as the study area in this paper.

3.1

Model results and analysis

The results of running the genetic algorithm for each parameter are as follows: crossover probability P_c = 0.9, variance probability P_m = 0.8, initialized population size is 200, and the maximum number of iterations is 500 generations. According to the above data and related parameters, the model is solved with the help of programming software using NSGA-II, resulting in 99 non-dominated solutions, and the set of non-dominated solutions of the three objective functions corresponding to each scheme is shown in Table 2.Fig. 3 shows the evolutionary curve of the fitness of the algorithm after 500 iterations, and the algorithm begins to converge from 120 generations onwards, which shows that the algorithm has a stronger ability of finding the optimal.

Table 2.

The corresponding objective function for each scheme

Order number	Cost / ten thousand yuan	Time / hour	Gravitati on	Order number	Cost / ten thousand yuan	Time / hour	Gravitati on
1	1407.22	2.2	32638.23	13	1441.96	1.44	27198.5
2	1170.72	2.4	24478.67	14	1445.81	1.25	27198.5
3	1412.07	1.51	29918.37	15	1225.83	2.4	27198.5
4	1205.66	2.35	24478.67	…	……	……	……
5	1413.7	1.47	27198.52	92	1845.62	0.89	32638.2
6	1424.82	1.48	29918.37	93	1347.16	1.55	27198.5
7	1437.24	1.58	32638.23	94	1919.16	0.8	32638.2
8	1359.92	1.52	27198.52	95	1394.86	1.47	27198.5
9	1352.11	2.2	29918.37	96	1893.32	0.81	32638.2
10	1307.37	2.28	29918.37	97	1351.91	1.49	24478.7
11	1312.86	1.58	27198.52	98	1772.25	0.94	29918.4
12	1884.22	0.84	32638.23	99	1845.62	0.89	32638.2

From the data in Table 2, it can be seen that each of the 99 scenarios has different advantages and disadvantages. For example, the 2nd scenario has the smallest total cost of 11,707,200 Yuan, which is a saving of 3,734,130 Yuan compared to the overall average cost. However, this scenario did not perform well in terms of gravity and rescue time. Specifically, the rescue time amounted to 2.40 hours, which exceeded the average rescue time for the scenario, and the gravitational force value of 24,478.7 was lower than the overall gravitational force average metric. Although the 87th scenario performed better in terms of rescue time and gravitational value, reaching the minimum and maximum values of 0.74 hours and 32,638.23, respectively, the total cost was as high as 2003,840,000 Yuan, which was the highest value among all the scenarios, which was not favorable for the construction of the Reserve Bank. Both the 2nd option and the 87th option have their limitations. When the cost of investment is more sufficient, the site plan with the smallest total time or the largest total gravitational force is chosen to improve the efficiency of emergency rescue, and when the cost of investment is limited, the three relationships are weighed to choose the optimal site plan.

3.2

Programmatic screening

Using the combined entropy-weight-TOPSIS method described above, the objective program is processed as follows.

Construct the weighting matrix and calculate the entropy value, weights and positive and negative ideal solutions, the objective function and the standardized results derived from the scheme to construct the weighting matrix, using the formula to calculate the entropy value, weights and positive and negative ideal solutions, the specific results are shown in Table 3 below.

Table 3.

Entropy values, weights and positive and negative ideal solutions

Name of index	Entropy value	Weight	Positive ideal solution	Negative ideal solution
Prime cost	0.975961	0.281278	0.281306	0.000028
Time	0.967633	0.37872	0.378758	0.000038
Gravitation	0.970942	0.340002	0.340036	0.000034

The above results provide some data support for the following proximity analysis, so that the research results are more realistic and reliable.

For the closeness and ranking, in order to more accurately and reliably analyze and study the comprehensive situation of the three objective functions, according to the weights of the indicators derived in the previous section to obtain the closeness of the cost, time and gravitational force indicators of the 99 programs, the specific analysis is shown in Table 4.

Table 4.

Closeness and ranking order

Name of index	Relative proximity	Name of index	Relative proximity
1	0.537339	13	0.51585
2	0.355945	14	0.557965
3	0.618677	15	0.393051
4	0.350116	……	……
5	0.515985	92	0.633924
6	0.623563	93	0.67881
7	0.67144	94	0.677623
8	0.517737	95	0.672332
9	0.471941	96	0.635342
10	0.468353	97	0.692494
11	0.515402	98	0.628608
12	0.671162	99	0.685945

The optimal solution selected from the above analysis is Solution 47, which has a cost of 15,658,300 yuan, of which 5,460,960,000 yuan is the cost of construction, 1,386,000 yuan is the cost of total staff salaries, 249,984,000 yuan is the cost of maintenance of the reserve, and 8,561,356,000 yuan is the cost of transportation. The total time spent was 97.21 hours and the total attraction was 32,638.23.

The number of reserve pools established was 9. The chemical enterprise pools were Fuxin Hengtong Fluorochemical Co. Ltd, Minlian Chemical Co. Ltd, Fushun Longfeng Chemical Factory, and Tieling Yuantai Chemical Co. Ltd, and the governmental pools were candidate pools 5, 11, 28, 63, and 64, respectively. The scheme achieves full coverage of 30 coal mine sites in Liaoning Province, and the locations of the reserve banks and the set of coal mine sites covered are shown in Table 5.

Table 5.

Location of the reserve bank and the collection of coal mine sites covered

Order Number	Reserve library type	Reserve name / number	longitude and latitude	Cover the coal mine point number collection
1	Enterprise reserve	Minlian Chemical Co., LTD	(123.498138,41.991741)	7
2		Fushun Longfeng Chemical Plant	(124.032753,41.858349)	10, 11, 12, 26, 27
3		Tieling Yuantai Chemical Industry Co., LTD	(123.557259,42.441074)	4, 5, 20, 21, 22, 23, 24, 25, 29
4		Fuxin Hengtong Fluorine Chemical Co., LTD	(121.601707,41.942741)	2, 3, 15, 16, 17
5	Government reserve	5	(123.37808,42.70544)	4, 5, 8
6		11	(121.65978,41.72352)	13, 14, 15, 16, 17
7		28	(124.57168,41.30891)	1
8		63	(121.3978,42.24609)	28
9		64	(123.26667,41.48151)	6, 9, 18, 19, 30

Using ArcGIS software we obtained Figure 4 and the results of the site selection study are shown in Figure 4.

As can be seen from Fig. 4, the black graphic area shows the locations of the 9 reserve depots and their numbers, and the green graphic area shows the geographic locations and numbers of the 30 coal mine sites. This site selection model has taken into account the locations and needs of all coal mines, and ensures that each coal mine can receive timely support for emergency supplies when needed.

First, for a particular coal mine, the distance and accessibility of its location to government or corporate reserves may affect the rescue relationship between them. For example, Government Reserve No. 28 provides rescue services for Coal Mine No. 1 (the coal mine number is known from Table 5), and Government Reserve No. 63 provides rescue services for Coal Mine No. 28. Similarly, the enterprise reserve Minlian Chemical Co., Ltd. provides rescue services for Coal Mine No. 7, and the enterprise reserve Fushun Longfeng Chemical Factory provides rescue services for Coal Mines No. 10, 11, 12, 26, and 27. Secondly, for coal mines that are located in geographically remote areas, like Coal Mines No. 6, 9, 18, 19 and 30, as there are no existing chemical plants in the vicinity, the establishment of Government Reserve No. 64 is required to provide rescue services for them. In addition, for some other mines, such as Coal Mines No. 20, 21, 22, 23, 24, 25 and 29, their rescue needs can be met by a single corporate reserve, the Tieling Yuantai Chemical Company Limited. Finally, for coal mines 2, 3, 15, 16, and 17, they are provided with rescue services by the enterprise reserve Fuxin Hengtong Fluorochemical Co., Ltd. and for coal mines 13 and 14, they are provided with rescue services by the government reserve No. 11. These cases show that geographic location has an important effect on the service relationship between the government and enterprise reserve pools and coal mines.

3.3

Comparative analysis

In order to prove the validity of the model, the site selection results of this paper are compared and analyzed with the established emergency stockpile system in Liaoning Province at this stage; the number of emergency stockpiles currently established in Liaoning Province is 11, which are located in Xihe District of Fuxin City, Guta District of Jinzhou City, Lianshan District of Huludao City, Tiexi District of Anshan City, Tieling County of Tieling City, Beipiao City of Chaoyang City, Hongwei District of Liaoyang City, Shuncheng District of Fushun City Tiexi District, Shenyang City, Xihu District, Benxi City, and Shuangtaizi District, Panjin City. On the basis of the model in this paper, the above method is used to process, and the program with the highest relative closeness is analyzed, and all other parameters are set the same. The comparison results for total emergency rescue time are shown in Figure 5, and other comparison results are shown in Table 6.

Table 6.

Compares the results

Scheme	This scheme	Contrast scheme
Total cost (ten thousand yuan)	1565.83	1732.14
Transportation cost (ten thousand yuan)	856.1356	922.4351
Establish the number of reserves	9	11
Total time (hours)	1.21	1.92
Total gravity	32638.23	38478.70

Firstly, in the current stage of the reserve depot system in Liaoning province, the total cost spent is 17,321,400 yuan, of which the transportation cost is 9,224,351 yuan, the total time spent is 1.92 hours, and the total gravitational force between the reserve depot and the coal mines is 384,787,70. The cost of this scheme is 15,658,300 yuan, the transportation cost is 8,561,356 yuan, and the total time spent is 1.21 hours and the total gravitational force between the reserve and the coal mine is 32638.23. As a result, in terms of the number of reserve depots established, this program saves 18.18% compared to the current program in Liaoning Province, and reducing the number of reserve depots is of great significance in improving the economy of the whole system. The cost spent on transportation increases by 23.94%, which is due to the fact that a reserve depot needs to provide rescue services for more coal mine sites, increasing the distance of individual transportation and thus the transportation cost. As for the total cost, this scheme saves 23.03% compared to the current stage scheme in Liaoning Province, which shows that this scheme effectively controls the cost. For the total gravitational force between the reserve and the coal mine, this scheme reduces the gravitational force by 15.18% compared with the current stage scheme in Liaoning Province. This is due to the fact that the number of reserve depots decreases and the distance between individual reserve depots and coal mines becomes larger, making the gravitational force decrease. As can be seen from Fig. 5, in this scheme the maximum time spent by the reserve depots to transport to a single coal mine is 0.68329 h and the minimum time is 0.216 h. At the present stage, the maximum time spent by the reserve depots in Liaoning Province to transport to a single coal mine is 0.71831 h and the minimum time is 0.26283 h, which is a saving of the maximum time of 0.03502 h and a saving of the minimum time of 0.04684 hours. In addition, the total time of emergency rescue, this program saves 36.98% compared with the current program in Liaoning Province, which is in line with the norms of the “14th Five-Year” National Emergency Response System Plan on rescue time, greatly improves the efficiency of rescue, and strongly ensures the safety of the affected people, which further proves the validity and reasonableness of this model.

The close cooperation between the government and enterprises provides strong support for effective response to emergencies. The optimal program establishes four enterprise reserve depots and five government reserve depots, reaching full coverage of 30 coal mines in Liaoning Province. This joint storage mode not only improves the economy of the reserve system, but also ensures that the rescue materials can arrive at the accidental coal mines quickly and accurately by shortening the rescue time, and at the same time, it makes the connection between the coal mines and the reserve depots closer. At the same time, it strengthens the connection between the coal mine and the reserve bank, and in the long run, this partnership model will also result in beneficial outcomes.

3.4

Sensitivity analysis

In order to deeply investigate the influence of different service radii on the siting and scheduling scheme of the model in multi-objective processing, this paper keeps other parameters unchanged, sets the service radii to 35 km, 40 km, 45 km, 50 km, 55 km, and 60 km, respectively, and repeats the above operation to derive the objective values of the optimal scheme under different service radii, which are shown in Table 7.

Table 7.

Optimal scheme target values at different service radius

Cover the radius / target value	Cost / ten thousand yuan	Time / hour	Gravitation
35 kilometers	1497.92	1.21	32638.23
40 kilometers	1725.78	1.5	32237.49
45 kilometers	1338.81	1.67	31478.67
50 kilometers	1858.79	1.92	29077.93
55 kilometers	1665.15	2.19	27358.08
60 kilometers	1662.98	2.54	24237.49

The total time, total gravitational force, total cost of the optimal solution derived from the maximum proximity value, as well as the number of reservoirs to be established, and the relationship between the service radius and the number of reservoirs are shown in Fig. 6.

As can be seen from Figure 6, the total number of reserve depots shows a decreasing trend as the service radius increases. This is because the expansion of the service radius allows the reserve bank to cover a larger area, thus providing rescue services to more coal mines. The number of enterprise reserves does not change with the trend of the number of reserves, indicating that the enterprise reserves have reached the minimum number of reserves and are reasonably distributed in different geographic locations. The trend of the number of government reserves is the same as the trend of the number of reserves, which is divided into two bands, and the number of government reserves reaches the highest value when the service radius is 30, 35, and 40. When the service radius is 45, 50, 55, or 60, the number of government reserves reaches its lowest value. The relationship between service radius and cost is shown in Figure 7.

As can be seen in Figure 7, with the increase of the service radius, the trend of the construction cost is the same as the trend of the number of reserves in Figure 6, and the construction cost reaches the highest value when the service radius is 30, 35, and 40. At the service radius of 45, 50, 55, 60, the cost of building storage reaches the lowest value. As for the total cost, there is a difference, in the service radius of 45km, the total cost is the lowest, this is due to the fact that in addition to the cost of construction, the total cost also includes the maintenance, transportation, employment costs, the cost of transportation in this scenario is 7,236,140,000 yuan, the distance between the coal mine and the reserve warehouse becomes smaller so that the cost of transportation is reduced by 1,325,176,000 yuan. In the actual rescue process, the cost required for rescue should not be considered only, the total time of rescue and the total gravitational force between the reserve depot and the coal mine are directly related to the efficiency of rescue. As shown in Fig. 8, the total time of rescue and the total gravitational force between the reserve and the coal mine change with the increase of service radius.

From Fig. 8, we can derive the following information: the optimal value of the target solution for total time tends to increase as the service radius increases, which indicates that as the coverage radius increases, the number of coal mines serviced by the reserve increases, and the rescue time increases as a result. And time is an inverse indicator. The smaller the target value, the higher the efficiency of rescue. Therefore, when the service radius is 35 km, the target value of total time is the shortest and the rescue efficiency is the highest. From Fig. 8, it can be seen that there is a certain contradiction between total gravity and total time. With the increase of service radius, the optimal value of the target solution of total gravitational force has a decreasing trend, which is due to the increasing coverage radius, the distance between the reserve and the coal mine increases, and the attractiveness has a decreasing trend. Total gravitational force is a positive indicator, and the higher value indicates the stronger rescue capacity of the reserve depot. The total attractiveness reaches the highest value when the service radius is 35 km, and the lowest value when the service radius is 60 km. This means that at a service radius of 35 km, the reserve has the highest rescue capacity. Choosing a suitable site selection plan and balancing the relationship between service radius and total gravitational force is crucial to improve the rescue capability of the reserve.

Overall analysis shows that the cost of this option is in the middle of the range when the service radius is 35 km. This means that the cost of the program is relatively reasonable and there is better control over the cost, which indicates that the cost-effectiveness of the program is at a higher level. The total time reaches the minimum value means that the total time spent in this time period is the least and the rescue operation is more efficient and rapid, which is a positive scenario indicating that the rescue operation is being carried out in an optimal way. Total gravitational force peaking indicates that the cooperation and synergy between the mine and the reserve is at its highest point, and this system ensures that the rescue supplies arrive without any problems, thus increasing the overall efficiency of the rescue operation. In the long run this means that the government and enterprises will gradually form closer and closer ties in the future long-term cooperation, which is conducive to the establishment of a better emergency coal mine rescue order.

4

Conclusion

In order to effectively solve the siting problem of coal mine reserve depot in Liaoning Province and explore the influence of different service radius on the siting scheme, this study adopts genetic algorithm to select the location of coal mine emergency reserve depot, which is favorable for material dispatching and economic management. Through the establishment of a multi-objective model and the comparison of the current system in Liaoning Province, this paper draws the following three conclusions: 1)

Using genetic algorithm, 32 enterprise reserve depots and 68 government reserve depots are selected as candidate reserve depots in Liaoning Province, and 99 scenarios are derived from NSGA-II, each of which covers all the coal mines in Liaoning Province, which verifies the reasonableness and validity of the algorithm in site selection and scheduling, and provides useful references for the planning and layout of the reserve depots.

2)

Through the entropy weight-TOPSIS combination method, the relative closeness of each scheme is compared to arrive at the optimal scheme as No. 47. From a cost perspective, the cost level of this scheme is in the middle of the range. However, the advantages and disadvantages of a scheme cannot be evaluated solely on the basis of the cost level, and other factors need to be considered comprehensively. In terms of time and gravitational force, Program No. 47 shows good performance. Time is an important evaluation index that reflects whether the materials in the reserve depot can efficiently reach the coal mine site. Gravitational force, on the other hand, represents the relationship between the reserve depot and the coal mine site. In both aspects, the 47th program is at a more excellent level.

3)

After comparing this paper’s scheme with the current stage of Liaoning Province’s reserve depot system, we find that this paper’s scheme has a significant advantage in terms of total cost and total time, and the total gravitational force between the reserve depot and the coal mines has been reduced, but in the overall analysis, this scheme has a high value of popularization and application, which can help to improve the efficiency of the rescue and the response speed, reduce the cost, and enhance the overall rescue capability.

In summary, the genetic algorithm can effectively establish the emergency reserve, and achieve one or more times of coverage for each coal mine to ensure the safety of coal mines, and the governmententerprise joint mode is in line with the relevant content of the national “14th Five-Year Plan” for the national emergency response system, which improves the efficiency of dispatching while minimizing the cost. These research results can provide advice to decision makers so that they can formulate effective site selection strategies and optimize the rescue layout. Meanwhile, under this model, a close linkage mechanism is formed between the government and enterprises, which is conducive to timely response and disposal of emergencies. The research content of this paper is limited, and only one mode of transportation is considered, and multiple modes of transportation can be considered in future research to further improve the study.

Lingua:: Inglese

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A study on site selection of coal mine emergency material reserve based on genetic algorithm

Tianyi Xia

Wenjun Fu

Xihua Zhou

Yumeng Wang

Zehao Jing

Zhibin Yang

Pubblicato online: 19 mar 2025

Ricevuto: 28 ott 2024

Accettato: 21 feb 2025

DOI: https://doi.org/10.2478/amns-2025-0488

Parole chiaveMulti-objective decision-making, Reserve depot, Genetic algorithm, Site selection program

© 2025 Tianyi Xia et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Parole chiave
Multi-objective decision-making, Reserve depot, Genetic algorithm, Site selection program