p-ISSN: 0972-6268 ature nvironment and ollution echnology N E P T (Print copies up to 2016) Vol. 20 No. 2 pp. 785-791 2021 An International Quarterly Scientific Journal e-ISSN: 2395-3454

Original Research Paper Originalhttps://doi.org/10.46488/NEPT.2021.v20i02.040 Research Paper Open Access Journal Vulnerability Measurement of Groundwater Inrush Channel in Mining Areas and Environmental Governance Measures – A Case Study on Taoshan Mine,

Wei Xiao Gang*(**), Dai Jun Wu*, Li Guang Hui**†, Hu Zhi Kai*** and Qin Sai*** *Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, China Earthquake Administration, 150080, China **College of Civil Engineering and Architecture, Zhengzhou University of Aeronautics, Zhengzhou 450046, China ***Kexing Construction Engineering Group Co., Ltd., Zhengzhou 450046, Henan, China †Corresponding author: Li Guang Hui: [email protected]

ABSTRACT Nat. Env. & Poll. Tech. Website: www.neptjournal.com The unrestricted resource behaviour of mines has caused considerable geological environmental problems. Specifically, the increasing water-induced accidents in mines affect safety production Received: 05-03-2021 and environmental safety in coal mines. To further decrease water inrush disasters to the maximum 31-03-2021 Revised: extent, vulnerability assessment of groundwater inrush channel in coal mines has become a primary Accepted: 05-04-2021 problem of chain-cutting disaster mitigation. In this study, first, influencing factors against formation Key Words: and project of water inrush channel in coals were analyzed comprehensively. Second, 14 indexes, Underground coal mines which influence the vulnerability of the water inrush channel, were selected from three perspectives of Water inrush channel coal seam features, coal quality features, and hydrogeological features. A case study based on data Vulnerability measurement of 56# coal seam and 68 coal seam of Taoshan Mine, China was carried out. The vulnerability of the Environmental governance groundwater inrush channel in the Taoshan Mine was estimated by analytic hierarchy process (AHP) Taoshan mine and fuzzy comprehensive evaluation. Results demonstrate that coal quality features, hydrogeological features, and coal seam features are major factors that influence the vulnerability of the water inrush channel. Among them, coal quality features contribute 48.36% of explanations to the vulnerability of the water inrush channel. According to the vulnerability grade evaluation results of fuzzy mathematics, the membership degree of belonging to “III” was 0.3731, which was the highest. This finding indicates that the vulnerability of the water inrush channel in Taoshan Mine belongs to grade III, which is a moderate state. Research conclusions have important references to perfect the evaluation index system for the vulnerability of water inrush channel in coal mines, provide early warning analysis of water inrush disasters in coal mines, and realize the mining–environmental protection coordinated development.

INTRODUCTION problems of coal mines by introducing scientific and rea- sonable evaluation systems can not only provide technical China has tremendous coal mines. The ecological envi- support to management planning of coal mines and solve ronment in coal mines is damaged seriously. Geological environmental problems in coal mines but also are one of the environmental protection and governance of coal mines are a important topics of modern environmental geological studies. large system project, which is characterized by a long period, large task, and complicated problems. Thus far, China has In particular, water inrush accidents in coal mines have not issued a perfect geological environmental governance been increasing continuously. To realize essential safety system of coal mines, divided the geological environmental and decrease disasters to the maximum extent, studying protection and governance in coal mines clearly, and released water diversion structures of the disaster causing ring in relevant technological standards at an appropriate time. The the coal disaster chain has become a primary problem geological environmental protection and governance of coal to chain-cutting disaster mitigation. With the increase in mines still cannot be balanced. With the long-term develop- exploitations in complicated and difficult-to-mine coal ment of coal resources, excessive mining phenomena occur, bodies, the underground hydrogeological conditions become thereby causing a series of environmental and geological more complicated. Traditional flooding disaster control problems, such as water and soil pollution, land resource technology of coal mines cannot adapt to new exploitation damages, geomorphologic landscape damages, and collapse environment and deviate from the engineering practices. of water inrush channel. Recently, China has never stopped New detection technology and method are necessary. The evaluations on the geological environmental impacts of coal vulnerability of water inrush channel of coal mines refers mines. Systematic evaluations of geological environmental to the possibility of disaster activation of the geological 786 Wei Xiao Gang et al. physical environment and engineering response features of of many coal mines in China, explored influencing factors water diversion structures in strata when the water inrush of water inrush by AHP, established a vulnerable index his- channel is used as the carrier and mining face approaches the togram, and proposed control measures to each risk grade. underground water source as well as the difficulties of system Based on the south region of Perak, Malaysia, Mogaji et al. recovery after the disaster. An evaluation index system for discussed the groundwater vulnerability prediction model the vulnerability of water inrush channel in coal mines was by using the ordered weighted average DRASTIC (The established. The higher vulnerability grade indicates that term “DRASTIC” stands for seven parameters in the model disasters can easily occur in coal mines, and specific defence which are depth to groundwater table (D), net recharge (R), measures are required. aquifer media (A), soil media (S), topography (T), impact of vadose zone (I), and hydraulic conductivity (C) method of PAST STUDIES GIS (Mogaji et al. 2014). Xiao et al. (2014) estimated water inrush evaluation of seam floor in 9# coal seams of Shanxi Studies on the vulnerability of water inrush channel in coal Liulin Hongsheng Jude Coal Industry Co. Ltd. through the mines are relatively weak. In engineering practices, the vulnerability index analysis. They compared the evaluation concept of vulnerability assessment is introduced for rap- results with the results of the traditional water inrush coef- id, reliable, and comprehensive detection of water inrush ficient evaluation technique. The results demonstrated that channel. Vulnerability, as an important index to measure the vulnerability index method, which considered various risk performance, characterizes the ability of the system to factors, was more advantageous. Liu et al. (2014) proposed resist disasters and maintain stability, including adaptabil- an AHP vulnerability index method based on GIS to evalu- ity, risks, and restorability. Janssen et al. (2006) introduced ate the water inrush phenomenon of many aquifers in seam the relevant concept of environmental vulnerability in the floor under complicated hydrological conditions and used global environment changes for groundwater vulnerability, it to evaluate the water inrush vulnerability of aquifers in the vulnerability of water inrush channel in coal mines and a coal mine. The results demonstrated that the proposed comprehensive environmental governance in coal mines. method solved the water inrush indication problem of seam Wu et al. (2008) believed that in Northern China, coal floor under complicated hydrogeological conditions. Li et exploitation was often influenced by groundwater inrush al. (2014) established a vulnerability index model of water from underground karst aquifer, established a geographical inrush channel of coal mines according to the coupling information system (GIS) for water inrush vulnerability evaluation, and determined weight coefficients of different theory of GIS and AHP, evaluated the probability of water influencing factors by using the artificial neural network. inrush in major minable seam roof and floors of the well Qiang et al. (2009) believed that water inrush was a geo- field, and proposed suggestions for safety production and logical disaster that influenced coal mine safety production water disaster control. Abdullah et al. (2015) designed the in China seriously. Based on powerful spatial data analysis groundwater pollution vulnerability diagram by using the functions of GIS, they established a neural network model of standard DRASTIC method and applied the linear structural water inrush risk assessment and carried out a case study by density diagram into the standard DRASTIC model to assure using the water inrush vulnerability index histogram. Rupert the accuracy of effects of potential pollution vulnerability. (2010) corrected the point rating scheme based on practical Wu et al. (2015) evaluated the water inrush vulnerability of groundwater quality data to improve the validity of the un- aquifer in Mengkeqing Mine, predicted mine inflow under derground water vulnerability map significantly by using the natural conditions and mining conditions, and proposed parameter statistical technology and geological information corresponding control measures. Li et al. (2016) evaluated system. Qiang et al. (2011) pointed out that water inrush from water inrush risk in mines by hydrochemical method and seam floor was a complicated nonlinear phenomenon, and it evaluated water inrush risk by analyzing concentrations of was controlled by various factors. In addition, a case study conservation ions through detailed hydrochemical investi- based on data of three coal seams in Tashan Mine, China gation and sampling. Wu, Qiang et al. (2017) believed that was carried out using the vulnerability index method of GIS. hydraulic pressure and water yield of the aquifer, equivalent Research results demonstrated that the vulnerability index thickness of the water-resistant layer, and geological struc- method of GIS had many potential advantages in evaluating tural property are the main factors to control water inrush; the possibilities of water inrush. Fijani et al. (2013) proposed they evaluated water inrush risks by vulnerability index a model based on artificial intelligence to improve the (VI) method by combining GIS and AHP. Based on existing groundwater vulnerability evaluation method of the aquifer studies, the vulnerability of the water inrush channel of coal in Maragheh–Bonab Plain, Iran. Qiang et al. (2013) believed mines is developed and perfected with the comprehensive that water inrush disasters influenced the safety production environmental governance of coal mines gradually. The

Vol. 20, No. 2, 2021 • Nature Environment and Pollution Technology VULNERABILITY MEASUREMENT OF GROUNDWATER INRUSH IN MINING AREAS 787

possibility of disaster activation of the geological physical In the matrix R, the element in the row i and column environment and engineering response characteristics of j (rij) indicates the degree of membership of the evaluated water diversion structure in rock strata as well as difficulties object to the grade fuzzy subset (vj) from the factor ( ui). of system recovery after a disaster are influencing factors of The performances of the evaluated object on ui is depicted vulnerability of water inrush channel in coal mines. Hence, an through the fuzzy vector (R|ui) = (ri1, ri2, …, rim) by the actual index system for the vulnerability of water inrush channel in value of one index in other evaluation methods. Finally, the coal mines was set up by combining the development law of weight vector of the evaluation factors was determined. In water inrush channel, incidence on the underground project the fuzzy comprehensive evaluation, the weight vector was gradually.gradually. TheThe possibilitypossibility ofof disasterdisaster activationactivation ofof thethe geologicalgeological physicalphysical environmenvironmeentnt andand gradually. The possibility afterof disasterdisasters, activation and difficulties of the in geologicalgovernance physicaltechnology. environm determinedent and as follows: engineeringengineering responseresponse characteristicsThischaracteristics index system ofof waswaterwater used diversiondiversion to evaluate structurestructure the vulnerability inin rockrock stratastrata asas wellwell asas engineering response characteristics of water diversion structure in rock strata as well as A = (a1,a2, ...... ,ap) …(4) difficultiesdifficulties ofof systemsystem recoveryrecoverygrade of the afterafter water aa disaster disasterinrush channel, areare influencininfluencin and somegg specific factorsfactors defence ofof vulnerabilityvulnerability ofof waterwater difficulties of system recoverymeasures after were a disaster adopted. are These influencin conceptsg havefactors extremely of vulnerability im- of waterIn Eq.(3), element ai in the weight vector A is the inrushinrush channel channel in in coal coal mines. mines. Hence, Hence, an an index index system system for for t hethe vu vulnerabilitylnerability of of water water inrush inrush channel channel inrush channel in coal mines.portant Hence, effects an indexon guaranteeing system for safe the production vulnerability and realizingof water inrushdegree channel of membership of factor ui to the fuzzy subset inin coal coal mines mines was was set set up upenvironmental by by combining combining protection the the development development of coal mines. law law ofTheof water water vulnerability inrush inrush channel, channel,of (important incidence incidence factors on on to the evaluated object). The relative in coal mines was set up by combining the development law of water inrush channel, incidenceimportance on sequence of evaluation indexes was determined thethe undergroundunderground projectprojectthe after afterwater disdis inrushasters,asters, channel andand difficulties difficultiesof coal mines inin was governancegovernance assessed basedtechnology.technology. ThisThis indexindex the underground project after disasters, and difficulties in governance technology. byThis AHP; index thus, the weight coefficient can be obtained. system was used to evaluonate existing the vulne studies.rability Evaluation grade of indexes the water of theinrush vulnerability channel, and some specific system was used to evaluof atewater the inrush vulne channelrability ingrade coal of mines the waterwere determined, inrush channel and , andAll some evaluation specific indexes were normalized before synthesis. system was used to evaluate the vulnerability grade of the water inrush channel, and somep specific defence measures were adopted. These concepts have extremely important effects on guarantee ing defence measures were anadopted. index system These was concepts constructed.evaluation have indexes extremelyThe were weights normalized important of influencing before synthesis. effects ona iguarantee1, ai  0 , ingin 1, 2, , .. A andand R R of the evaluated objects defence measures were adopted. These concepts have extremely important effects on guaranteei1 ing p safe production and realizfactorsing wereenvironmental concluded byprotection AHP, and ofvulnerability coal mines. grade The was vulnerabilit were synthesizedy of the by using an appropriate operation, through safe production and realizing environmentalof the protection evaluated objects of coalwere symines.nthesizedevalu ation Theby using indexes vulnerabilit an appropriatewere normalizedy ofoperation, the before through synthesis. which the ai 1, ai  0 , in1, 2, , . A and R safe production and realizing environmental protection of coal mines. The vulnerability of the i1 water inrush channel of judgedcoal mines by combining was assessedvector fuzzy of basedfuzzy mathematics. comprehensive on existing Finally, evaluation studies specific results. Evaluation (B ) ofwhich the evaluated indexes the vector objects of ofwere fuzzy obtained comprehensive. evaluation results water inrush channel of coal mines was assessed based on existing studiesof therr evaluated. Evaluation r objects indexes were synthesized of by using an appropriate operation, through which the comprehensive environmental protection measures 11of coal 12 1m water inrush channel of coal mines was assessed based on existing studiesvector. Evaluation of fuzzy comprehensive(B indexes) of the evaluatedof evaluation objectsresults ( Bwere) of the obtained. evaluated objects were obtained. the vulnerability of water inrush channel in coal mines were determined,rr 21and 22 an index r2m system was …(5) the vulnerability of watermines inrush were channel proposed. in coal mines wereA R determined aa1,,, 2 apm , and an indexbb 12system,,, b was  B the vulnerability of water inrush channel in coal mines were determined, and an index system was rr11 12 r1m constructed. The weights of influencing factors were concluded by AHP, and vulnerability grade  constructed. The weights of influencing factors were concluded by AHPrrp12, and p vulnerability rpm grade rr21 22 r2m …(5) A R aa,,, a bb,,, b  B constructed. The weights ofMODEL influencing AND factors INDEX were SYSTEM concluded by AHP, and vulnerability grade1 2 pm 12 …(5) waswas judgedjudged byby combiningcombining fuzzyfuzzy mathematics.mathematics. Finally,Finally, specificspecific comprehencomprehensivesive environmentalenvironmental where b1 is obtained from operation of A and column j of R. It expresses the degree of was judged by combining fuzzy mathematics. Finally, specific comprehensive environmental rrp12 p rpm protectionprotection measures measures of of coal Fuzzycoal mines mines Hierarchy were were propose propose Comprehensivemembershipd.d. of the evalua Evaluationted object toMethod the grade fuzzy subset νj, in general. protection measures of coal mines were proposed. where bi is obtained from operation of A and column j of Index System where b1 is obtained from operation of A and column j of R. It expresses the degree of MODELMODEL AND AND INDEX INDEXFuzzy SYSTEM SYSTEM hierarchy comprehensive evaluation is used to quan- R. It expresses the degree of membership of the evaluated MODEL AND INDEX SYSTEM Influencing factors of the vulnerabilitymembership of water inrushof the evaluachannelted in objectcoal mines to the we gradere summarized fuzzy subset νj, in general. FuzzyFuzzy H Hierarchyierarchy C Comprehensiveomprehensivetize the fuzzy E Eindexesvaluationvaluation of the M M evaluatedethodethod object by constructing object to the grade fuzzy subset nj, in general. Fuzzy Hierarchy Comprehensive Evaluationbased Method on academic studies on permeabilityIndex Slawystem of water inrush formation and engineering practice Fuzzy hierarchy comprehensivea grade fuzzy evaluation subset experiences is(this used approach to. Meanwhile, quantize determines an the index fuzzy sythestem degreeindexes of the vulnerability of the evaluated of groundwater inrush channel in Fuzzy hierarchy comprehensive evaluation is used to quantize the fuzzyInfluencing indexes factors ofIndex ofthe the Systemevaluated vulnerability of water inrush channel in coal mines were summarized Fuzzy hierarchy comprehensiveof membership). evaluation Then, is usedTaoshan various to Mine quantize indexes was proposed theare ,combined fuzzyconsider indexesing theby possi the of bility the of evaluated available index data (Table 1). object by constructing a grade fuzzy subset (this approach determinesbased the ondegree academic of mstudiesembership). on permeability law of water inrush formation and engineering practice object by constructing afuzzy grade transformation fuzzy subset principle.(this approachTable 1: Index determine system of the vsulnerability the degree of groundwater of membership). inrush channel in Coal Mines. object by constructing a grade fuzzy subset (this approach determines theexperiences degree .of Meanwhile, mInfluencingembership). an index factors system of of thethe vulnerabilityvulnerability of groundwaterof water inrushinrush channel in ThenThen, ,various various indexes indexes a arere combined combinedFirst, the domainby by the the fuzzy offuzzy discourseLevel transformation transformation-1 indexes of factors Lev prin ofprinel -the2 indexesciple.ciple. evaluated Units Variable No. Then, various indexes are combined by the fuzzy transformation principle.Taoshan Mine waschannel proposed in, consider coal minesing the were possi summarizedbility of available based index on data academic (Table 1). Mine ventilation system State grade X1 FirFirst,st, thethe domaindomain ofofobject discoursediscourse was determined; ofof factorsfactors ofitof re thethefers evaluatedevaluated to the P evaluation objectobject waswas index, determineddeterminedTable 1studies: Index; ; it its ystem refersonrefers permeabilityof the toto v ulnerability law of g roundwaterof water i nrushinrush channel formation in Coal Mines and. Relative gas emission First, the domain of discourse of factors of the evaluated object was determined; itm3 /trefers to X2 as follows: volume engineering practice experiences. Meanwhile, an index thethe P P evaluation evaluation index index, ,as as follows follows: : Coal seam features Level-1 indexes Level-2 indexes Units Variable No. the P evaluation index, as follows: Coal seam stability systemState grade of the vulnerabilityX3 of groundwater inrush channel Mine ventilation system State grade X1 u  uu12,, , up Coal seam thickness …(1) m …(1) X4 u  uu12,, , up in Taoshan … Mine(1) was proposed, considering the possibility  Relative(1) gas emission 3 u uu12,, , up Water content Ma % … X5 m /t X2 Second, the domain of discourse of comment gradesCoal was seam features of available volumeindex data (Table 1). Second, the domaindetermined, of discourse as offollows: comment grades was deteAshrmined content , as follows:Ad % Coal seam stability X6 State grade X3 Second, the domain of discourse of comment grades was determined, as follows: Indexes are divided into qualitative indexes and quanti- Second, the domain of discourse of comment grades was determinedVolatile con,tent as follows: Vdaf% Coal seam thickness X7 m X4  Coal quality features (2) vv vv vv12,,,, , ,v vp …(2) ……(2)  12 p Gel layer tativeYmm indexesWater incontent studies X8 on the vulnerabilityMa% of groundwaterX5 v  vv12,, , vp …(2) After constructing the grade fuzzy subset,S evaluation inrushSt,d% channelAsh content in coalX9 mines. TheAd% qualitative indexesX6 in After constructing the grade fuzzy subset, evaluation factors ui (i = 1, 2, …, p) of the After constructingfactors the grad u (i e= 1,fuzzy 2, …, subset, p) of the evaluation evaluated object factors areP quantizedui (i = 1, 2,Table Pd…% , 1p contain) of the mine ventilationX10 system, coal seam stability, After constructing the grade i fuzzy subset, evaluation factors ui (i = 1, 2, …, p) of theVolatile content Vdaf% X7 evaluated object are quantized one by one. In other words, the degreeWater-resist ingof layer membershipC oal quality featureswater-resistingState ( gradeR│ ui) of the layer, waterX11 filling characteristics, number of evaluated object are quantizedone by one. one Inby other one. words, In other the words, degree theof membership degree of membership (R|ui) (R│ui) of the evaluated object are quantized one by one. In other words, the degree of membership (R│ui) of theGel layer Ymm X8 of the evaluated object to the grade subsetWater wasfilling characteristics determined coalState grade seams, and fault nature.X12 The data of all six indexes were evaluatedevaluated objectobject toto thethe gradegrade subsetsubset waswas determineddeterminedHydrogeological features ffromrom aa singlesingle facfactortor toto obtainobtain thethe fuzzyfuzzyS St,d% X9 evaluated object to the gradefrom subset a single was factor determined to obtain thefrom fuzzy a single relationNumber offac coal matrix, seamstor to asobtain statisticalState the grade fuzzy evaluation resultsX13 through a questionnaire survey relation matrix, as follows: P Pd% X10 relation matrix, as followsfollows:: Fault nature ofState geologicalgrade experts X14and research members. The data of relation matrix, as follows: Water-resisting layer State grade X11 RuRu|| 1 Indexesrr11rr are 12divided into r1 rm qualitative indexes andthe quantitative remaining indexes quantitative in studies indexes on the were collected from the Ru|1rr11 12 r1m 1 vulnerability11 12of groundwate1m r inrush channel in coal minesgeological. TheWater qualitative filling survey characteristics andindexes research in Table reportsState1 grade in Taoshan Mine.X12 RuRu|| 2 rr21rr 22 r2 rm Hydrogeological features …(3) 2  21 22 2m Number … of( coal3) seams State grade X13 RRRu| 2 containrr21  mine 22 ventilation r2m system, coal seam stability, water-resisting layer, water filling    …(3) R characteristics, number of coal seams, and …(3)fault nature. The data of allFault six nature indexes were statisticalState grade X14 EMPIRICAL STUDY Ru| evaluationp rr resultsp12 pthrough a questionnaire rpm survey of geological experts and research members. The Ru| p rrp12 p rpm Indexes are divided into qualitative indexes and quantitative indexes in studies on the Ru| p rrp12 p rpm data of the remaining quantitative invulnerabilitydexes were collected of groundwateTaoshan from the Mine rgeological inrush is locatedchannel survey andinin the researchcoal eastern mines . regionsThe qualitative of the Westernindexes in Table 1 In the matrix R, the element in thereports row in iTaoshan and Mine.column j ( r ) indicates the degree of In the matrix R, the element in the row i and column j (containrijij ) indicates mine ven thetilation degree system, of coal seam stability, water-resisting layer, water filling In the matrix R, the element in the rowEMPIRICAL i and column STUDY j ( rij ) indicates the degree of membership of the evaluated object to the grade fuzzy subset ( ch) aracteristics,from theNature factornumber Environment of( coal). seamsThe and , and Pollution fault nature. Technology The data •of Vol. all six20, indexes No.2, 2021 were statistical membership of the evaluated object to theTaoshan grade Mine fuzzy is locate subsetd in the eastern(vvj ) fromregions theof the factor Western (uProductionui ). The Zone in Mine, membership of the evaluated object to the grade fuzzy subset ( v ) fromevaluationj the resultsfactor through ( u ). a Theiquestionnaire survey of geological experts and research members. The and the administrative regionj is classified to Taoshan Distirict, Qitaihe City. Taoshan mine is pperformanceserformances ofof thethe evaluatedevaluated objectobject onon uui i isis depicteddepicted throughthrough thethe fuzzyfuzzy vectorvector ((RR││uui)i) == ((rri1i1, , bordered at Taoshan Fault in the eastdata, and of itthe is adjacentremaining to thequantitative Xinfu Mine. indexes In the w cereoal collectedmine, the from the geological survey and research performancesri2, …, rim) byof the actualevaluated value object of one on index ui is in depicted other evaluation through methods.the fuzzy Finally, vector the(R│ weightui) = ( vectorri1, ri2, …, rim) by the actual value of one index in other evaluation methods.reports Finally, in Taoshan the Mine. weight vector ri2, …, rim) by the actual value of one index in strikingother evaluationlength and incline methods.d width were Finally, approximately the weight 5 and 5 vectorkm, respe ctively. The inclined area ofof thethe evaluatievaluationon factorsfactors wwasas determined.determined. InIn thethe fuzzyfuzzy comprehensivecomprehensive evaluation,evaluation, thethe weightweight of the evaluation factors was determined. Inand the the fuzzyarea of miningcomprehensive right were aEMPIRICALpproximately evaluation, 25 and STUDY the 22.9952 weight km2, respectively. On the north vectorvector was was determined determined as as follows follows: : vector was determined as follows: Taoshan Mine is located in the eastern regions of the Western Production Zone in Qitaihe Mine, A aa12,, , ap …(4) A aa12,, , ap and the administrative region … is (classified4) to Taoshan , Qitaihe City. Taoshan mine is A  aa12,, , ap  …(4) bordered at Taoshan Fault in the east, and it is adjacent to the Xinfu Mine. In the coal mine, the In Eq.(3), element ai in the weight vector A is the degree of membership of factor ui to the In Eq.(3), element ai in the weight vector A is the degree of membershipstriking length ofand factor incline du widthi to the were approximately 5 and 5 km, respectively. The inclined area In Eq.(3), element ai in the weight vector A is the degree of membership of factor ui to the fuzzyfuzzy subsetsubset (im(importantportant factorsfactors toto thethe evaluatedevaluated object).object). TThehe relativerelative importanceimportance sequencesequence ofof 2 fuzzy subset (important factors to the evaluated object). The relativeand importance the area of miningsequence right wereof approximately 25 and 22.9952 km , respectively. On the north evaluationevaluation indexesindexes waswas detedeterminedrmined byby AHPAHP; ; thusthus, , thethe weightweight coefficientcoefficient cancan bebe obtained.obtained. AllAll evaluation indexes was determined by AHP; thus, the weight coefficient can be obtained. All 788 Wei Xiao Gang et al.

Table 1: Index system of the vulnerability of groundwater inrush channel in coal mines.

Level-1 indexes Level-2 indexes Units Variable No. Coal seam features Mine ventilation system State grade X1 Relative gas emission volume m3/t X2 Coal seam stability State grade X3 Coal seam thickness m X4 Coal quality features Water content Ma% X5 Ash content Ad% X6

Volatile content Vdaf% X7 Gel layer Ymm X8 S St,d% X9 P Pd% X10 Hydrogeological features Water-resisting layer State grade X11 Water filling characteristics State grade X12 Number of coal seams State grade X13 Fault nature State grade X14

Production Zone in Qitaihe Mine, and the administrative system of the vulnerability of groundwater inrush channel region is classified to Taoshan District, Qitaihe City. Taos- was constructed based on the principle of AHP (Saaty et al. han mine is bordered at Taoshan Fault in the east, and it is 1985). Calculation results are listed in Table 2. adjacent to the Xinfu Mine. In the coal mine, the striking Table 2 shows that coal quality features, hydrogeological length and inclined width were approximately 5 and 5 km, features, and coal seam features can influence the vulner- respectively. The inclined area and the area of mining right 2 ability of the water inrush channel significantly. The coal were approximately 25 and 22.9952 km , respectively. On quality features contribute 48.36% of the explanation to the the north edge, railways run through the Qitaihe Station, vulnerability of the water inrush channel. The upper 40–48 connect to the National Railway, and extend all regions in coal seams in Taoshan Mine belong to the semi-bright coals, China. Highways extend to Yilan, Kiamusze, , Baoqing, which are mainly dominated by bright coals. Bright coals and Harbin, and Duisu Port. Hence, the traffic con- have glassy lustre, stripped structure, endogenous fracture ditions are very convenient. The mine exploitation began in development, and high vulnerability. The middle 55–79 coal 1958. The disk deviation well group was adopted, followed seams belong to semi-bright coals and semidark coals in by technological reconstruction and construction. In the stripped and lamellar structures. Massive structures account coal mine, the total thickness of the coal-bearing seam was for a high proportion, and the coal seams have a large amount approximately 1470 m, which covers 65 coal seams, and of internal dirt. Hydrogeological features contribute 34.87% the average total thickness of coal seams was 38 m. The of the explanation to the vulnerability of the water inrush coal-bearing coefficient was 2.6%. The 56# coal seam and channel. Taoshan mine has many small rivers and valleys, 68# coal seam were selected as the research object for fuzzy and it belongs to an aged river. After several diversion, the comprehensive evaluation of the vulnerability of water watercourse twists and turns, forming many cutoff lakes. The inrush channel. river width is 20-30 m, the water depth is approximately 4 m, and the maximum flooding water level is 165 m. Large and Determination of the Weight of Evaluation Indexes small gobs below the groove are superficial, and the surface Based on AHP soil is thin; thus, the water filling in the ore bed is affected AHP transforms the semiqualitative and semiquantitative to some extent, easily causing vulnerability of water inrush problems into quantitative computation by constructing a channel. Moreover, surface water bodies are a water filling pairwise matrix, calculating weight vectors, consistency factor in Taoshan Mine; they are mainly catchments during test, and weight sequencing, and making a comprehensive rainy seasons in several valleys. Surface runoffs penetrate judgment on weights of evaluation indexes of water inrush underground through surface collapse pits in the gob and channel. When selecting evaluation indexes, the principle can influence water filling in coal mines. Coal seam features of reflecting the primary and the most comprehensive infor- contribute 16.77% of the explanation to the vulnerability of mation by the least indexes should be observed. An index the water inrush channel. Recently, Taoshan mine manage-

Vol. 20, No. 2, 2021 • Nature Environment and Pollution Technology

bed is affected to some extent, easily causing vulnerability of water inrush channel. Moreover, surface water bodies are a water filling factor in Taoshan Mine; they are mainly catchments during rainy seasons in several valleys. Surface runoffs penetrate underground through surface collapse pits in the gob and can influence water filling in coal mines. Coal seam features contribute 16.77% VULNERABILITY MEASUREMENTof the explanation OF GROUNDWATER to the vulnerability INRUSH of the IN water MINING inrush AREAS channel. Recently,789 Taoshan mine management agency has focused on safety management and adopted centralized inflow and zoned Table 2: Weights of Indexes of the vulnerability of waterventilation inrush channel. measures. The gross installed capacity of the major fan is 1615 kW. The total air inflows in the entire coal mine are 13100 m3/min, and the total ventilation volume is 1435 m3/min. Variable No. Name of variables Level-1 weights Level-2 weights Total weights The effective wind volume in the entire mine is 92%. As a result, the possibility of gas explosion X1 Mine ventilation system 0.1677 0.1113 0.0187 is decreased. The level-2 weight of coal seam stability (X3) is 0.5329, which has occupied more X2 Relative gas emission volume 0.0674 0.0113 than half of the weights of the level-1 index coal seam features. The reason is that the total coal X3 Coal seam stability 0.5329 0.0894 seam thickness in wells is approximately 1470 m, which covers 65 coal seams. The average total X4 Coal seam thickness 0.2884 0.0484 thickness of the coal seam is 38 m, and the coal-bearing coefficient is 2.6%. The coal seam X5 Water content 0.4836 0.1590 0.0769 features have four stable coal seams and four relatively stable coal seams, and the remainder X6 Ash content 0.1845 0.0892 includes unstable coal seams. X7 Volatile content 0.1983 0.0959 X8 Gel layer Vulnerable Grade Evaluation Based on0.0494 Fuzzy Mathematics 0.0239 The fuzzy mathematics maximum membership principle was used to evaluate the vulnerability of X9 S 0.1554 0.0751 X10 P the water inrush channel and obtain specific0.2535 and explicit ambiguous0.1226 problems. A comprehensive X11 Water-resisting layer fuzzy mathematics0.3487 model was constructed.0.1399 In accordance with 0.0488the index system and quota of the X12 Water filling characteristicsindexes, the standard eigenvalues of five0.4551 levels of indexes were0.1587 recognized, thereby obtaining the X13 Number of coal seams standard eigenvalue matrix A. Subsequently0.0723, fuzzy evaluation was0.0252 implemented. The fuzzy subset X14 Fault nature was evaluated by combining the weights0.3327 of AHP and the membership0.1160 matrix. The principle of obtaining the larger product was used. After normalization, the maximum was selected as the ment agency has focused on safety managementevaluat anded adopted grade of themembership vulnerability principle. of the water According inrush channel to Eqs. according (1)-(4), theto thefuzzy maximum fuzzy centralized inflow and zoned ventilation measures. The gross evaluation matrix of level-1 indexes was as below. installed capacity of the major fan is 1615 kW.mathemati The totalcs memberair ship principle. According to Eqs. (1)-(4), the fuzzy evaluation matrix of 3 inflows in the entire coal mine are 13100 m /min, and the 0.3970 0.4234 0.0966 0.0257 0.0573 3  total ventilation volume is 1435 m /min. Thelevel effective-1 indexes wind was 0.1367 0.1657 0.4775 0.2046 0.0155 . According to Eq. (5), the comprehensive volume in the entire mine is 92%. As a result, the possibility 0.2315 0.3243 0.3613 0.0829 0.0000 of gas explosion is decreased. The level-2 weight of coal fuzzy evaluation vector was [0.2134 0.2642 0.3731 0.1322 0.0171]. The results show that the five seam stability (X3) is 0.5329, which has occupied more than According to Eq. (5), the comprehensive fuzzy evaluation half of the weights of the level-1 index coalnumbers seam features. are memberships vector of was the vulnerability[0.2134 0.2642 of water 0.3731 inrush 0.1322 channel 0.0171].to “I, II, III The, IV and V”, and The reason is that the total coal seam thicknessthe membership in wells is to results“III” is show 0.3731, that which the five is thenumbers highest. are Hence, memberships the maximum of the membership approximately 1470 m, which covers 65 coal seams. The vulnerability of water inrush channel to “I, II, III, IV and V”, principle indicates that the vulnerability of the water inrush channel in Taoshan mine belongs to average total thickness of the coal seam is 38 m, and the and the membership to “III” is 0.3731, which is the highest. coal-bearing coefficient is 2.6%. The coal seamGrade features III, indicating have Hence, the moderate the maximum state of vulnerabilitymembership of principle the water indicates inrush channel that in Taoshan four stable coal seams and four relatively stablemine. coal seams, the vulnerability of the water inrush channel in Taoshan and the remainder includes unstable coal seams. mine belongs to Grade III, indicating the moderate state of POLICY SUGGESTIONSvulnerability of the water inrush channel in Taoshan mine. Vulnerable Grade Evaluation Based on FuzzyStrengthening Geological Environmental Monitoring in Coal Mines Mathematics Strengthening geologicalPOLICY environmental SUGGESTIONS monitoring and management in coal mines. A responsibility system shall be implemented for geological environmental restoration in coal mines. The fuzzy mathematics maximum membership principle was Strengthening Geological Environmental Monitoring used to evaluate the vulnerability of the waterT inrushhe principle channel that thein party Coal that Mines explores coal mines is held responsible for the protection and the and obtain specific and explicit ambiguousparty problems. that destroys A the coal mines is responsible for governance shall be observed. Responsibilities comprehensive fuzzy mathematics model was constructed. In Strengthening geological environmental monitoring and accordance with the index system and quotaof of all the links indexes, shall be implementedmanagement thoroughly in coal mines., and a Amanagement responsibility mechanism system and shall system shall be the standard eigenvalues of five levels of indexes were rec- be implemented for geological environmental restoration in ognized, thereby obtaining the standard eigenvalue matrix A. coal mines. The principle that the party that explores coal Subsequently, fuzzy evaluation was implemented. The fuzzy mines is held responsible for the protection and the party that subset was evaluated by combining the weights of AHP and destroys the coal mines is responsible for governance shall the membership matrix. The principle of obtaining the larger be observed. Responsibilities of all links shall be implement- product was used. After normalization, the maximum was se- ed thoroughly, and a management mechanism and system lected as the evaluated grade of the vulnerability of the water shall be established and perfected to strengthen monitoring inrush channel according to the maximum fuzzy mathematics and management of all coal mines, especially those that are

Nature Environment and Pollution Technology • Vol. 20, No.2, 2021 790 Wei Xiao Gang et al. destroyed seriously. Thus, regulations on the protection and improving standards; (6) adopting comprehensive govern- governance of coal mines are developed. The monitoring ance, controlling energy and water resources, which are col- of geological environmental restoration and governance in lected from coal mines, performing full-process monitoring coal mines shall be strengthened. Relevant departments shall on wastes and emissions during mining activities, increasing increase supervision and verification of mining application, monitoring strength, and urging enterprises to reform green expanding secondary mining scale and changing the mining clean mineral industries; (7) promoting green clean mining mode. Mining protection and governance restoration scheme technologies positively and applying the philosophy of green shall be formulated. Mining closing, mining termination, and cleaning mining industry into mining, transportation, and land reclamation can only be implemented after acceptance processing of coal mines. by relevant departments. CONCLUSIONS Improving Environmental Engineering Governance of Coal Mines Excessive or disordered coal resource exploitation leads to occurrences of geological disasters in coal mines, such as Barren rocks at open mining edges are cleaned. Two sides collapse, landslide, debris flow, and surface collapse. The are solidified, and the surface is greened. On one hand, ecological environment in mining areas and surrounding catchwater should be constructed on top of mountains to areas are worsened and the ecosystem is degenerated due to stop water flow into the stope and further cause groundwater vegetation damages. Water inrush in coal mines is a typical pollutions or trigger geological disasters. On the other hand, natural disaster, which negatively affects normal production the land use scope of mining activities must be restricted. and environmental protection of coal mines. Influencing Land resources shall be used reasonably and standardly, and factors of formation and project of water inrush channel in all random stacking phenomena shall be eradicated. Waste coal mines are analyzed. Then, 14 indexes that influence the residues, which are produced in the mining process, are used vulnerability of the water inrush channel are selected. A case scientifically, and resource recycling is realized. When coal study based on data of 56# and 68# coal seams in Taoshan mines are closed, waste residues can fill in the stope to prevent Mine, China is carried out. The vulnerability of the water pollution from the source. The green vegetation in the mining inrush channel is estimated by AHP and fuzzy comprehen- area that protects some vegetation transplantation shall be sive evaluation. Results demonstrate that coal quality features adopted in the mining process rather than deforestation. This influence the vulnerability of water inrush channel mostly, approach can prevent excessive vegetation damages, thereby followed by hydrogeological features and coal seam features causing great disasters. Moreover, trees and grasses shall be successively. The vulnerability grade evaluation results of planted appropriately, the green area shall be expanded in fuzzy mathematics suggest that the membership of “Ⅲ” is the coal mine, and the vulnerable ecological problem in the 0.3731, indicating that the Taoshan Mine belongs to “III” mining area must be eliminated. After coal exploitation, a in terms of vulnerability of the water inrush channel. This large-area gob can cause floor cracks, surface collapse, and reflects that the vulnerability of the water inrush channel of settling. The collapse and fractures shall be filled up timely, Taoshan mine is in a moderate state. Finally, three govern- and large-area settlement shall be flattened timely. ance measures of strengthening geological environmental Strengthening Technological Content of monitoring, improving environmental governance, and in- Environmental Protection in Coal Mines creasing technological content for environmental protection in coal mines are proposed. In-depth studies on enriching Details are introduced as follows: (1) increasing efforts in influencing factors of vulnerability of water inrush channel, research and development of deep processing of mineral re- geological environmental comprehensive evaluation, and sources, expansion of peripheral industrial chains of mineral recovery and governance of geological disasters in coal resources, and increasing mining products; (2) enriching deep mines are required in the future. processing technology of mineral resources and extending in- dustrial chain; (3) adjusting mineral exploitation technology ACKNOWLEDGMENT and introducing the automatic and scientific mineral mining system; (4) improving management level, decreasing num- This work was supported by the Foundation of Science ber of operation posts, and attempting to realize unmanned and Technology Innovation Leading Talent project of Cen- mineral exploitation comprehensively; (5) promoting green taline thousand talents plan (194200510015), Foundation clean mineral industrial development positively, shutting of Henan Science and Technology Project(192102310465, down mines with resource wastes and severe pollutions 202102310240), Foundation of Key Scientific Research through technological reforms, optimizing management, and Project of Universities of Henan Province (19A560023), and

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Nature Environment and Pollution Technology • Vol. 20, No.2, 2021