# Exploration and Research on the Propagation Law of Seepage Risk Network in Tailings Storage Facility

Authors: Zhixin Zhen; Xuewei Ma; Bo Ma
Journal: Discrete Dynamics in Nature and Society
 (2021)

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## Abstract

The seepage accident of a tailings pond poses a serious threat to the stability of tailings dams and the surrounding environment. To reduce the occurrence of seepage accidents, this paper studies the identification of seepage hazards, the propagation law of seepage risk, the importance of hazards, and the priority of hazard treatment. To overcome the subjectivity and omission of hazard identification, according to the complexity and dynamics of tailings seepage, this paper proposes the evidence-based identification method of three-dimensional seepage hazards (EIMTSH) to identify the hazards of the tailings seepage system and the relationship between hazards. Then, on the basis of identifying the hazards of the tailings seepage system, the propagation network of seepage risk in tailing ponds (PNSRTP) is constructed based on the complex network theory. By analyzing the characteristics of the PNSRTP, it can be found that the propagation of seepage risk is scale-free and small-world. Through the node deletion method, this paper finds that the nodes with a higher degree value can reduce the network efficiency more quickly and should be governed first. By giving priority to the treatment of hazards with higher degree, the propagation of seepage risk can be reduced more quickly and the risk management level of tailings ponds can be improved, which is helpful to realize the sustainable development of mining production.


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## Body

## 1. Introduction

Tailings pond is a kind of geotechnical facility used for storing mine waste, which is called tailings in the mining industry. The composition of tailings is very complex, which may show strong corrosive, volatile, acidic, and other characteristics affected by the types of minerals mined. If the tailings cannot be managed effectively, the tailings may leak under the action of seepage, mainly in the form of flowing soil, piping, contact erosion,contact flowing soil, etc., which is called tailings seepage [1]. Seepage accident of tailings pond is one of the typical accident types of tailings pond, which not only directly pollutes the surrounding environment but also destroys the stability of the tailings dams. In serious cases, it will lead to dam breaks, causing greater accidents and ecological disasters [2, 3].Seepage refers to the flow of fluid in porous media. The material which is composed of granular or fragmentary material and contains many pores or fissures is called the porous medium. Seepage is widely used in many fields. Tong Shujiao et al. used the two-dimensional seepage accident consequence analysis software to analyze the temporal and spatial variation law of leakage poison concentration [4]. In order to improve the design, management, and follow-up restoration of the landfill site, Shu et al. proposed a new simplified method to calculate breakthrough time of municipal solid waste landfill liners [5]. He et al. studied the biological damage to Sprague-Dawley rats by contaminated groundwater from rare earth metals tailings pond seepage at the individual, organ, tissue, and cell level [6]. CA López-Morales and Lilia conducted research on seepage in wastewater treatment and reuse processes [7].In order to correctly analyze the change law of seepage field and stress field caused by tailings storage and rainfall, we should attach great importance to the identification of seepage hazards. Hazard identification, also known as risk identification, is an important basis for risk management [8]. To achieve the sustainable development goals, Li used the official data of the Belt and Road Initiative (BRI) countries from year 2000 to year 2015 to identify socioeconomic vulnerability to natural hazards of Belt and Road Initiative countries [9]. Makowski and Niedbalski used the geomechanical method to identify rock burst hazards in underground mining, which helped to predict rock burst accidents before mining operations [10]. Ibrahim used the national data of fire anomalies to analyze the risk of waste-fires in Sweden and found that controlling upstream hazards in waste management chain helped to reduce the risk of fire [11]. Ferreira et al. proposed a hazard classification system based on the use of the CFs of the virtual substances as a hazardous reference to help perform a preliminary screening, which can be integrated with other criteria to facilitate the identification of PBT chemicals [12]. Wu Deng et al. improved the safety level of complex systems by optimizing complex systems [13–15].For the seepage problem of the dam body, there are dozens of common identification methods for hazards, such as fault type and impact analysis, prehazard analysis, checklist method, hazard and operability research, fault tree analysis, and event tree analysis [16]. In addition, some new methods are also applied to the identification of dam hazard. Gao Shipei et al. combined the detection of levee engineering with numerical simulation analysis, so as to determine the location, outline, and size of levee hazard [17]. Based on the distributed optical fiber temperature measurement technology, Wang monitored the leakage volume of homogeneous earth dam and the damage degree of optical fiber geomembrane, so as to realize a more comprehensive monitoring of the hazard of seepage field [18]. Ma et al. have conducted treatment and research on the leakage hazard of Yuecheng dam in combination with the engineering practice [19].The cause of seepage accident in tailings pond is complex, and many influencing factors are coupled with each other. At the same time, the seepage system is constantly changing with the construction of tailings pond, which creates a big problem for the characterization of seepage risk propagation process in tailings pond. Complex network has the characteristics of node diversity and connection diversity, which can better represent the internal relationship between research objects (nodes) [20]. In order to promote the sustainable use of rare earths (RE), Xibo Wang built an embodied RE network by combining both input-output analysis and complex network theory [21]. Jiujie Shi used thw complex network analysis method to analyze the historical evolution of the international plastic wastes trade and showed that China’s management policies are the main driving forces for the expansion and shrinkage of the global plastic wastes trade network [22]. Guo S took the Chinese construction industry as an example and conducted research and exploration on the accident behavior risk chain network based on the accident causality theory [23]. Mohmand and Wang studied the structural properties of the Pakistan railway network (PRN) [24]. After the construction of the complex network which represents the relationship between nodes, scholars began to try to use the characteristics of the complex network to find the key nodes that dominate the operation of the network. Yu et al. converted the critical node identification problem in complex networks into a regression problem and presented it to identify critical nodes with the best spreading ability [25]. Because it is difficult to distinguish the importance of nodes with the same degree, an average shortest path centrality to rank the spreaders was proposed [26]. Zhen et al. initially tried to apply the important nodes of complex network identified by the network centrality index to the prevention of tailing pond accidents [27].


## 2. Research Overview

In order to explore and study the propagation law of seepage risk in tailings storage facility, this paper studies this problem in three steps. Firstly, based on the constitution and function of the seepage system of tailings ponds, the hazards in different life cycle stages of the tailings pond are identified objectively and systematically by using laws and regulations, literature, and accident cases, and the list of seepage hazards and propagation paths of seepage risk are determined after the same hazards are integrated. Secondly, based on the list of seepage hazards, this paper uses the Pajek software to construct the propagation network of seepage risk in tailing ponds (PNSRTP) for the first time; Finally, this paper analyzes the characteristics of this PNSRTP with the help of some analysis methods in the complex network theory and tries to find the key hazards that dominate the propagation of seepage risk from the perspective of reducing the network efficiency. The entire research process of this paper is shown in Figure1.Figure 1
The flow chart of research methods and results.


## 3. Identification of Seepage Hazard in Tailings Pond

### 3.1. Identification Method

A hazard may cause loss of life, injury, or other health impacts, property damage, social and economic disruption, or environmental degradation [28]. In this paper, according to the characteristics of the tailing pond seepage system with the dynamic change of tailing pond life cycle, combined with industry laws and regulations and technical specifications, the seepage hazards of tailing ponds are divided into three modes or three states from the perspective of safety production. The first state is the dormant hazard, which is the initial factor or event to cause the seepage. It is an indirect factor and cannot be triggered by other factors or events. Its state is basically stable. The second is the armed hazard, which refers to the intermediate state of hazard evolution. It may evolve from the dormant hazard, or other armed hazards may cause it [29]. The third is the active hazard, which mainly refers to the seepage events that are happening [29].The causes of seepage accidents in tailings pond are complex, and the seepage system changes continuously with the life cycle of tailings pond. These characteristics make it difficult to identify the seepage hazards in tailings ponds. Although some scholars have proposed a series of hazard identification methods for such dynamic complex systems, these methods are mainly based on the experience and subjective judgment of the identification personnel. The result is that some key hazards may be missed [30]. In order to overcome the above shortcomings, this paper proposes a method to identify the seepage hazards of tailings pond, which is called the evidence-based identification method of three-dimensional seepage hazards (EIMTSH), as shown in Figure 2.Figure 2
The evidence-based identification method of three-dimensional seepage hazards.It can be seen from Figure2 that the EIMTSH includes three dimensions and each point in the space specifically represents the seepage hazards and influencing factors at each life cycle stage of tailings ponds under different supporting evidence. The Y-axis is composed of eight subsystems of the tailings pond seepage system, mainly including pond area subsystem, personnel subsystem, conveyor subsystem, drainage subsystem, monitoring subsystem, dam subsystem, material subsystem, and management subsystem. Each subsystem can be divided into different modules according to its function and structural characteristics. The Z-axis is the life cycle stage of tailings pond, which mainly includes construction stage, operation stage, closing stage, and reclamation stage or recovery stage. The division method of Z-axis and Y-axis is used to divide all the objects that need to be identified at different time periods and in different subsystems [29]. The X-axis is the supporting evidence used to identify the potential seepage hazards of tailings ponds, mainly including the relevant technical specifications and laws and regulations, seepage accident cases, literature, news media information, etc., as shown in Appendix A, B, and C [29].In order to find out all the seepage hazards, the paper analyzes the Code for Design of Tailings Facilities (GB 50863-2013), Code for Construction and Acceptance of Tailings Facilities (GB-T 50864-2013), and other evidence in Appendix A and then extract the hazards and the influence mechanism between hazards in each content one by one [29]. At the same time, referring to the content in Appendix B and Appendix C, we can get all the hazards of the seepage system in tailings ponds that has not been integrated, that is, all the spatial nodes in Figure 2. After integrating these identified hazards, all hazards of the seepage system in tailings ponds can be obtained, as shown in Table 1.Table 1
List of seepage hazards in tailings pond.
Tailings dam subsystemModules of the subsystemNumber (v)Hazard nameEvidenceNumber of hazards causedPond area subsystemPond environment2FloodW1-1.2.1, W6, W7, W8, W97, 19, 60, 62, 64, 65, 66, 67, 69, 150, 151, 156, 158, 167, 190, 191, 192, 193, 195, 273, 3253Ice and snowF2-3.4, W719, 67, 112, 181, 1954Strong windW5, W1-3.4.47, 19, 66, 3255Heavy rainfallW5, W9, W4, W6, W7, W8, F4, C2, C11, C1319, 67, 69, 150, 151, 193, 1956Extreme temperature changesW1-3.4.4, W719, 62, 65–67, 191, 232, 267, 3257SurgeW6, W1-3.4.4, F1-4.2, W6, C3, C1162, 65–67, 69, 150, 151, 190, 1938Beyond standard earthquakeW5, W2-3, W9, W11, W12, W4, W6, F419, 60, 62, 64–66, 70, 136, 150, 151, 191, 192, 232, 267, 273, 3259MudslideW2-2, W10, W83910Gravel foundationF1-4.1, W2-3, F315711Liquefied soil, soft clay, and collapsible loess foundationF1-4.1, W2-3, F3, C268, 70, 135, 136, 15712Water burst in the tailings pondF1-5.7, W2-3, F3127, 15813Karst cave or existence of mine shaftsF1-4.1, W2-3, F368, 135, 136, 15814Insufficient geological explorationW1-3.4.4, W6, F4, F389, 12115Failure to do engineering geological weaving and surveying during excavation and tunnelingW1-3.4.4, F5, F4, F334716Failure to predict and forecast engineering geological problems that may occur during constructionW1-3.4.4, F5, F4, F312117Inadequate research on adverse geological problems and improper handling measuresW1-3.4.4, F4, F319, 12118No engineering geological and hydrogeological surveys were carried out when the tailings dam reached the corresponding heightW1-3.4.4, F5, F319, 121, 34719Landslides in the tailings pondF6, W1-3.4.4, W9, W10, W67, 39, 19520The overburden of the bank slope connected to both ends of the tailings dam is thinW1-3.4.4, F315821The rock on the bank slope is broken, joints are developed, or faults pass throughW1-3.4.4, W8, F319, 15822Animals burrow, camp, and graze illegallyW1-3.4.3, W1-3.4.419, 64, 66, 150, 151, 15823Private digging in the tailings impoundmentW1-3.4.4, W2-3, W619, 64, 66, 150, 15124Illegal soil borrowing behind the damW1-3.4.4, W2-3, W664, 66, 15725There are mining activities near the siteF1-3.1, W2-3, W619, 62, 64, 6626Inappropriate selection of pond locationF1-3.1, W11, F310–13, 20, 21, 25, 32–34, 52, 208Selection of pond location31Open pits and depressions reserve tailings without special safety demonstrationF1-3.113532Insufficient impoundment length (upstream wet tailings impoundment)W1-1.1.13933The dam site is not conducive to the layout of drainage structuresF1-6.1, C820034Large catchment areaW2-2, W2-3, W8195Tailings pond construction35Unreasonable multidatabase phased construction planF1-139, 19436No operation plan for the joint impoundmentF1-139, 19437Overdue service of tailings pondF1-7, W9, W11, W5, W839, 65-66, 70, 73, 183, 191–193, 232–23438Inaccurate storage capacity calculationF1-3.239, 19439Insufficient storage capacity of tailings pondF1-3.2, W919042No antifreeze measures have been taken for tailings facilitiesF1-10, F1-1166, 112, 191, 232, 24443Antifreezing measures have not been finished before freezingF1-1066, 112, 191, 232, 24444Blasting construction does not meet the technical specificationsF2-4.2, W619, 62, 64–66, 191Material subsystem45Tailings particle size/gradation does not meet the requirementsW1-3.5.2, W9, F347, 48, 50, 51, 66, 68, 61, 23446Excessive flow of tailings slurryF1-11, W1-3.5.250, 61, 233, 234, 26747Excessive tailings unit weightW1-3.5.2, C251, 52, 68, 61, 23348Concentration and consistency of tailings slurry do not meet the requirementsF1-11, W1-3.5.250, 51, 68, 61, 233, 23449Strongly corrosive tailingsF1-11, W1-3.5.2, W12, C3, C9233, 23850Tailings are highly abrasiveF1-11, W1-3.5.223351Unqualified dry beach-covering materialsW1-3.4.453, 157, 158, 19552Unqualified filling materialsF2-3.364–68, 70, 73, 135, 136, 15753Erodible tailings exposureW1-3.4.4, C3, C5, C6157Dam subsystemDam body63Decrease of dam elevationW6, W11, W6, C239, 190, 19465Dam deformationW1-3.4.5, W8, C262, 64, 157, 267, 27366Dam crackF6, W1-3.6.6, W6, W7, C8, C11–C1362, 64, 73, 15867Dam surface water saturationW2-3, W3, W662, 64–66, 73, 15768Uneven settlement of the damW1-3.6.6, W6, C962–66, 191, 192, 267, 27369Scouring of the damW6, W2-3, W6, W7, C11, C1362, 64–6670Tailings liquefactionF1-4.4, W1-1.1.4, W8, W962, 64, 68, 136, 156–15871Defects in seismic calculation of tailing pondF1-4.47272Improper seismic designF1-4.4, W862, 64, 66, 70, 73, 135, 13675Improper calculation method of tailings dam stabilityF1-4.4, W464, 73, 77–81, 89, 90, 92–9477The tailings dam slope ratio is unreasonableF1-4.5, W4, W762, 64, 65, 73, 15778Unreasonable width of dam crestF1-4.5, W462, 64, 65, 15779Improper dam type selection for the initial damW1-1.1.239, 64, 15780The height of initial dam is unreasonableF1-4.1, W939, 64, 65, 73, 81, 88, 19481The ratio of the initial dam height to the total dam height of the upstream tailings dam is unreasonableF1-4.1, W964, 65, 7382The dam layout is unreasonable (the location of subdam and primary dam)F1-4.1, C232, 39, 69, 73, 13561Poor control of tailings depositsW1-1.1.364, 65, 68, 77, 152, 154, 155, 15783The rising speed of tailings between dam downstream and upstream is unbalancedW1-1.1.36184The rising speed of the dam does not meet the requirements of the rising speed of the sedimentary beachW1-1.1.380, 61, 85, 8685The accumulation dam is too highF1-4.1, F562, 64, 65, 8186The height of the accumulation dam is lower than the height of tailings accumulationF1-4.1, F539, 65, 88, 190, 19487Defects in the layout of maintenance passages of the primary damF1-4.5, F565, 66, 8288The requirements for discharge under ice cannot be met in frozen areasF1-4.111289The upstream method is used to build dams on the seismic zoneF1-4.160, 62, 7090Fine-grained tailings dams using the direct methodF1-4.164, 65, 6191Unreasonable setting of tailings dam bermF1-4.565, 66, 8292The tailings dam is not equipped with antiscouring measuresF1-4.6, F569, 8293No filtration water and sediment storage dams are built in the centerline and downstream tailings damsF1-4.664, 8294Unreasonable height of the filtration water and sediment storage damsF1-4.639, 64, 6595Defects of step arrangement on the outer slope of accumulation damF1-3.465, 66, 82Dam filling96Use of only one tailings discharge point for a long timeF1-3.4, W2-361, 86, 15297Long time no replacement of tailings discharge pointF1-3.4, W2-361, 86, 15298The tailings discharge method does not match the direction of advancementF1-3.4, W2-361, 15299The branch pipes that discharge tailings are opened too littleF1-3.4, W2-361, 152, 234100Failure to evenly discharge tailingsF1-3.4, W2-361, 86, 152101Unreasonable layout of ore branch pipeF1-3.461, 86, 88, 152, 234102Layered filling and layered compaction are not carried outF2-3.4, F564–66, 68, 77103Improper method of sectionalized filling and rollingF2-3.4, F564–66, 68, 77, 122104Unreasonable slope of the top surface of layered rollingF2-3.4, F564–66, 68105The tailings discharged into the pond are not leveled and rolledF2-3.4, F586106Improper selection of tailings leveling and compaction equipmentF2-3.4, F577, 104, 122107Rolling is perpendicular to the dam axisF2-3.4, F565, 66, 104108Laying the upper layer of new materials before the dam body is qualifiedF2-3.4, F565, 66, 68, 104, 122, 158109The filling and rolling of the cohesive tailings dam is not continuousF2-3.4, F565, 66, 68, 104, 122110Improper pavingF2-3.4, F564–66, 68, 104111Downhill paving when the ground is unevenF2-3.4, F564–66, 68, 104112The dam is filled with ice, snow, or other debrisF2-3.4, F564–66, 68, 158113Improper unloading methodF2-3.4, F565, 66114Filling and slope adjustment are not carried out at the same timeF2-3.4, F564, 66, 77115Construction machinery and personnel crossing the dam surface in violation of regulationsF2-3.4, F565, 66116Resuming work in violation of regulationsF2-3.4, F5112117The maintenance platform in downstream dam slope is defectiveF2-3.465, 66, 73, 122118Unreasonable determination and modification of dam construction indicatorsF2-3.464, 77, 78120The subsidence allowance of the dam filling is unreasonableF2-3.465, 66, 158121Improper handling of dam-bank junctionW1-3.4.465, 66, 73, 158122There is a horizontal weld on the slopeF2-3.664, 66, 73124Slope cutting did not follow the design requirementsF2-3.6, F519, 64, 65125Slope protection was not carried out in timeF2-3.6, F519, 62, 64, 65, 73, 122126Unreasonable design of cast-in-place protective surfaceF2-3.619, 62, 64–66, 73, 77, 122, 157127When the dry storage method is adopted, the accumulated water in the pond area is not discharged in timeF1-564, 67128Mixing dry and wet tailings when using dry storageF1-564, 65, 68129Tailings pond of insufficient depth and water resources chooses wet storageF1-539Dam foundation131Poor construction quality of vertical antiseepage facilitiesF2-3.266, 157, 165132No effective filter layer is set on the dam foundationW1-3.4.4131, 157, 165133The concrete cutoff wall is not on the fresh bedrockF2-3.2131, 157, 165134Inadequate protection measures after dam foundation excavationF2-3.266, 131, 135, 136135Uneven foundation subsidenceW1-1.4, W963–66, 68, 73, 136, 191, 267, 273136Dam foundation instabilityF4, F6, W1-1.4, W11, W12, W8, W964–66, 68, 73137The protective layer reserved has not been removed before filling when the natural clay is used as the dam foundationF2-3.2, F5131, 133, 135, 136, 158138No measurement and set-up before clearing dam foundationF2-3.2, F5131, 133, 135, 136, 165139Untreated strong weathered layer and broken zone of rock foundationF2-3.2, F5131, 133, 135, 136, 158140Improper handling of the alluvium above the bedrockF2-3.2, F5131, 133, 135, 136, 158141Irregular grouting work for dam foundation treatmentF2-3.2, F5131, 135, 136, 157Dry beach145No coverage measures in the pond areaW1-3.4.453, 157146The main dam has not been reclaimed and greened in timeF1-5.753147Insufficient soil cover or greening on the dam slope (dry)W1-3.4.4, F1-5.753148Weakness of paving has not been reinforcedW1-3.4.4, F5158130Poor construction quality of horizontal pavingW1-3.4.4157149The length or thickness of the horizontal paving in front of the dam is insufficientW1-3.4.4157150Natural paving (covering) is destroyedW1-3.4.4158151The protective layer (cover) of the dry beach is destroyedW1-3.4.453, 158152Poor deposition control for dry beach faceW1-3.4.4, F4154, 155, 157154The minimum dry beach length does not meet the requirementsF1-4.2, W864, 167155The minimum free height does not meet the requirementsF1-4.2, W864, 167Seepage156Leakage damageF6, W1-3.4.4, W2-3, W8, W9, W11, W12, C1-C1360, 62, 64157Filter failureW1-3.4.4, W864, 67, 136, 156, 167, 195158Leakage channelW1-3.4.4, W8, C1, C5, C9-C10, C12-C1364, 68, 135-136, 156159No special seepage simulation experiments were done for the 1st and 2nd level tailings dams according to the terrain conditionsF1-4.393, 162, 167160The seepage calculation of the dam body was not carried out in the preliminary design stageF1-4.393, 162, 167161The expanded or heightened tailings pond did not carry out the dam seepage calculationF1-4.3162, 167162Unreasonable antiseepage designW1-3.4.467, 156-157164The dam foundation area between the initial dam and sediment storage dam is not equipped with drainage facilitiesW1-3.4.4157165Defects of dam foundation drainage facilitiesW1-3.4.4157166Inaccurate confirmation of critical and control seepage linesF1-4.3167167Seepage line is higher than control seepage lineF1-4.3, W11, W3, F4, C165–67, 154–156168Improper measures to reduce the seepage lineF1-4.3167169Improper construction connection of impermeable geosyntheticsF2-4.3157, 165, 184170Insufficient protection measures for seepage prevention facilitiesF2-11158, 165, 183171Improper selection of soil for the soil cushionF2-11157, 165, 184172Unqualified soil pad compactionF2-11157, 165, 184173Improper laying of geomembraneF2-11, F4157, 165, 184365The HDPE geomembrane did not conduct visual inspection and physical performance index testing before layingF5-11.3173366The laying amount of HDPE geomembrane exceeds the amount of welding that can be completed in one working dayF5-11.3173367When laying the HDPE geomembrane, unfold first and then dragF5-11.3173368Improper windproof measures of HDPE geomembraneF5-11.3173369After the HDPE geomembrane was laid, no welding was carried out within the specified timeF5-11.3173370Welding seam and welding inspection and quality control are not carried out in the HDPE geomembrane layingF5-11.3173371The vehicle is rolled directly on the HDPE geomembrane and the HDPE geomembrane is damagedF5-11.3173372The laying of HDPE geomembrane does not allow for expansion and contraction of the materialF5-11.3173174Unqualified geomembraneF2-11157, 165, 184175No drainage measures under the geomembrane protective layerF2-11157, 165, 184176Poor drainage of composite geotechnical drainage networkF2-11157, 165177Improper installation of composite geotechnical drainage networkF2-11157, 165, 176, 183178Improper construction of sodium bentonite matF2-11157, 165, 184360The sodium bentonite pad appears wrinkled and suspendedF5-11.5178361Personnel and vehicles rolled on on the sodium bentonite padF5-11.5178362Improper repair materials and scope for damaged parts of sodium bentonite padF5-11.5178363Construction of sodium bentonite pad under rain and snowF5-11.5178364The construction of sodium bentonite mat shows a crossF5-11.5178179The materials are poured down from the top of the slopeF2-3.5184180People walking, rolling stones, and handling other materials on the paved filter layerF2-3.5183181Ice and snow and debris are mixed in the filter materialF2-3.5182182Unqualified filter materialF2-3.5183183Filter failureF2-3.5, W2-3, W3, F465, 157, 165184Unqualified filter layer pavingF2-3.5, F466, 183186Improper laying of geotextileF2-3.5165, 184187Geotextile cloggedF2-3.5165, 183188The geotextile is exposed to the sun for a long timeF2-3.5165, 183189Unreasonable geotextile designF2-3.5165, 183Drainage subsystemDrainage plan190OvertoppingF6, W2-3, W9, W12, W11, F4, C1, C3, C1160, 62, 64, 69191Fracture of drainage structureW1-3.4.4, F466, 69, 127, 158, 192, 200192Leaking drainage structureW1-3.4.4, F4, C766, 67, 69, 127, 150, 151, 158, 195, 200193Scour or cavitation drainage structuresW1-3.4.4, F4191, 192194Insufficient regulating water storageW1-3.4.439195Rapid rise of pond water levelW1-3.4.4, W2-3, C2, C139, 65, 67, 152, 154, 155, 167, 190, 194196No drainage facilitiesF1-6.1127, 195, 200197The foundation pit at the higher groundwater level has no drainage facilitiesF1-6.1195, 200198The flood drainage system does not match the dam construction methodF1-6.3, F4191, 200199The determination of the flood control standard of the tailing pond is not accurateF1-6.1127, 190, 194, 200200Insufficient flood discharge capacityF1-6.2, F6, W9127, 193, 195201Blocking defects of flood drainage facilitiesF1-6.3192, 193, 195, 200202Unreasonable temporary flood control plan during construction periodW1-3.4.4195, 200203Improper diversion measuresW1-3.4.4195, 200205The installation location and elevation of drainage facilities do not meet the design requirementsF1-6.1, F4193, 195, 200206Insufficient elevation of drainage holes in front of the damF1-6.1200207Flood drainage structures are directly located on the tailings sediment beachF1-6.1, F4191208The foundation of the flood drainage structure is set in the area with poor engineering geologyF1-6.1191209Insufficient foundation bearing capacity of underground flood drainage structuresF1-6.1191210Improper installation of flood interception and drainage facilitiesF1-6.1, F4191, 200211The dry tailings pond of third-class and above adopts flood interception ditch for flood dischargeF1-6.1, F4200212Drainage facilities are not located in front of the blocking damF1-5.6193213Use of mechanical flood drainageF1-6.2200214The on-site line setting is inconsistent with the construction drawingF2-3.177, 78, 205, 210, 237, 273, 274215Confluence calculation is not accurateF1-6.2, F4195, 200216Use of unproven non-24-hour rainfall durationF1-6.2215218Improper installation of energy dissipation facilitiesF1-6.3191, 193219No energy dissipation measures have been taken in the tailings facilityF1-6.3191, 193220The maximum flow rate of flood is greater than the allowable flow rate of the building materialsF1-6.2191, 193Backwater plan221The clarified water of the tailings pond is not used for backwater utilizationF1-9, F4195222One-sided pursuit of backwater qualityW1-3.4.3, W8, F4195224Low tailings water recovery rateF1-9195227Insufficient volume of backwater pondF1-9224Conveyor subsystemConveying facilities231Leaks in transmission facilitiesF6, W1-3.4.4, W8, C469, 61, 150–152232Broken conveying facilitiesW1-3.4.4, W1269, 100, 231, 253233Scour or cavitation transportation facilitiesW1-3.4.4232, 238-239234Blockage or siltationW1-3.5.2100, 165, 176, 191, 195, 200, 232, 253235No overload alarm signal and protection deviceF1-1046, 191, 233-234, 239236No flow and pressure detection instrumentF1-1046, 191, 233-234, 239237The installation location and elevation of the transportation facilities do not meet the design requirementsF2-10234238Serious corrosion of equipmentW1-3.4.4, W11, W12191, 231-232, 253, 325239Serious wear and tear of conveying facilitiesW1-3.4.4231-232, 253240No anticorrosion treatment in tailings facilitiesF1-6.3, F2-5.3, W9233, 238, 244241Unqualified anticorrosion materialsF2-5.3193, 233, 238, 244242Improper anticorrosion constructionF2-5.3, W11193, 233, 238, 244244Incident pool defectW1-3.5.5231245Improper installation of the instrument of the thickenerF1-10, F446–48, 233, 238, 239246Unreasonable area of thickening tankW1-3.5.5, F2-10, F4250247The height of the thickening tank is unreasonableW1-3.5.5, F2-10, F4231, 250248Improper selection of thickening tankW1-3.5.5, F2-10231, 250249Improper selection of the inclined plate and inclined pipeW1-3.5.5231-232, 238-239, 250250Insufficient production capacity of the thickenerW1-3.5.5234251The pipelines and valves of the conveying equipment are not connected tightlyF2-10, F4231, 238, 239, 253252Flocculant preparation and addition do not meet the requirementsF1-1047-48, 234, 253253Concentration equipment failureF2-1047-48, 231, 234, 250258Waste mixed into tailings slurryW1-3.5.247–50, 65, 112, 233-234, 238-239, 253, 267260Improper handling of local hydraulic phenomenaW1-3.5.2233-234, 238-239, 267261Unreasonable selection of classification equipmentW1-3.5.545, 254, 264262No spare grading equipmentW1-3.5.5264263The pressure of the cyclone to feed the tailings is unstableW1-3.5.545, 233, 239254Damaged grading equipmentW1-3.5.545, 231, 234, 263, 264264Insufficient cyclone production capacityW1-3.5.5234265Damaged dredgerW1-3.5.5234266Insufficient production capacity of dredgerW1-3.5.5234Other transportation facilities267Pipes and grooves deformationF2-5.3191, 193, 232, 234, 239268Defects of the interception ring the in pipe bodyF2-5.369, 192, 193269The pipe body is in direct contact with the big rocksF2-5.3191, 232, 267270The outer wall of the pipe is not protectedF2-5.3191, 232, 267271The dimensions of pipes, grooves, tunnels, etc. do not meet the requirementsF1-6.3, W1-3.5.2191, 193, 234, 267272Pipes and grooves material unqualifiedF1-11, F4191, 193, 232, 267273Subsidence or deformation of supporting facilities such as pipes, trenches, and tunnelsF1-11, F2-4.3191, 232, 267274Improper installation of supporting facilitiesF1-11,F2-4.3191, 232, 267, 273275Excessive slope deviation for laying pipes, trenches, tunnels, etc.F1-11, W1-3.5.2191, 193, 233, 234, 239, 267276Improper design of corners of pipes, grooves, tunnels, etc.F1-11191, 193, 233, 234, 239, 267277Improper subgrade design of pipes and groovesF1-11193, 233, 234, 239278Improper design of slope ratio of pipe trench and embankmentF1-11, F4193, 239279The pipe opening was not closed when the pipeline installation and laying were suspendedF1-11192280Pipes and grooves failed the pressure testF1-11, F2-8.4191, 232, 267281Poor quality of fill around the pipelineF1-11191, 267282The axial filling height of the pipe in the dam body is differentW1-3.4.4191, 267283Improper rolling of the backfill on the top of the facilityW1-3.4.4191, 267284Improper pipe weldingF1-6.3191, 192, 233, 251, 267285No settlement joints between pipe and wellF1-6.3191, 233, 267286The joint length of the drain pipe is unreasonableF1-6.3191, 192, 233, 267287Deformation joints are not provided at both ends of the drain pipe according to the design requirementsF1-6.3191, 233, 267288Lax masonry of pipe wallsF2-5.2192, 232, 233, 251289Improper excavation (pipes, trenches, tunnels, etc.)F2-4.2, F2-5.265, 66, 87, 91, 95, 117, 120, 131, 133, 191Pump293Pump selection does not meet the requirementsF1-12, W1-4.446, 195, 200, 232, 234, 307294Insufficient capacity of pumping station designF1-9, F1-12195, 200296Poor pump qualityF1-12, W1-4.4192, 193, 233, 234, 239, 307297Unreasonable valve selection in pumping stationF1-12, W1-4.4192, 234, 251, 307298Improper pump station configurationF1-12, W1-4.446, 192, 195, 234, 307378There are no flow and pressure detection instruments in the pumping stationW1-4.4298379Defect of buffer device in pumpW1-4.4298380Defects of the slurry pipeline in the pumping stationW1-4.4298299Improper installation of pumpsF1-11, W1-4.4192, 195, 200, 233, 234, 307307Pump failureF1-11, W1-4.461, 100, 127, 192, 195, 200, 231373No liquid can be discharged from the sand pumpW1-4.4307374Insufficient liquid output from sand pumpW1-4.4307375Pump consumes too much powerW1-4.4307376Pump bearing heatW1-4.4307377Deformed or broken pump shaftW1-4.4307308Closure design not in accordance with regulationsF1-6.3, W5, F419, 37, 62–70, 73, 135, 136, 148, 157, 158, 167, 183, 191, 192, 232, 234, 238, 254, 265, 267, 273, 307, 314309The tailings pond are closed without understanding the hidden dangers and risksF1-7, W5, F4, F366, 310, 312, 313310The surrounding environment improvement does not meet the requirementsF1-7, W519312Dam body renovation does not meet the requirementsF1-7, W562–70, 73, 135, 136, 148, 157, 158, 167, 183,313The improvement of flood discharge system does not meet the requirementsF1-7, W5191, 192, 195, 234, 267, 273, 307314No plans for reclamation and ecological restoration after closure designF1-7, W5, F419315Unreasonable reclamation planW2-5, W8, F419, 310, 312, 313316Simultaneous mining and discharge of tailings in a tailings pondF1-8, F465, 66, 68, 61, 151, 152, 157, 158, 191, 232317The upstream wet-stacking tailings pond adopts the recovery method advancing from the embankment to the pondF1-864–66318Mechanical excavation of tailings near drainage facilitiesF1-8191, 192, 267, 273320Unreasonable tailings recovery planF1-8, F464, 151, 157, 158, 191, 192321Stability analysis and safety measures of the tailings dam and the slope is insufficientF1-819, 64, 73Monitoring subsystem324Improper selection of monitoring instruments and equipmentF1-3.4, W8, F4, C2235, 327, 343325Monitoring instrument failure and work interruptionF1-3.4, W8, C2327, 343326The third-class and above tailings ponds are not equipped with monitoring facilities that combine manual and automatic monitoringF1-3.419, 22–24, 154, 155, 231, 327327Safety monitoring facilities cannot fully reflect the operating status of the tailings pondF1-3.4, C27, 19, 22–24, 37, 45–50, 65–69, 135, 136, 191, 192, 200, 267, 343328No monitoring points are arranged outside the dam toeW1-3.4.519, 22, 23, 231, 310, 327329No additional monitoring facilities are installed at the dam abutment, bedrock faults, and buried pipes in the damW1-3.4.565–69, 135, 136, 191, 192, 267, 327330No monitoring of the amount and composition of tailings entering the pondF1-3.445–50, 327331No external drainage and composition monitoringF1-3.4200, 327332No monitoring of groundwater and surrounding water bodiesF1-3.4327334The number of water quality monitoring wells around the tailings pond is insufficientF1-3.4327336The setting of monitoring facilities is not included in the construction planF2-3.7325, 327337Improper safety monitoring during tunnel excavationF2-6.1214, 271, 273–276, 289, 327Management subsystem339Insufficient capital investmentW2-3, W314–18, 24, 31, 37, 42, 52, 89, 90, 92, 93, 132, 134, 145–148, 159–161, 164, 196, 197, 221, 235, 236, 240, 268, 293, 294, 308, 310, 312, 324, 326, 328–334, 351,340Insufficient safety supervisionW2-3, W11, W12, W5, C47, 14–19, 22–24, 26, 31, 36, 37, 42–52, 60, 62–70, 73, 74, 76–173, 174–178, 179–214, 218–298, 299, 307, 308–337, 346, 348, 351–355343Inadequate safety evaluationW2-3, W3, W519, 31, 60, 156, 190, 200, 224, 231, 327344Outdated specifications and standards for survey, design, construction, and acceptanceW2-3, W314–18, 23, 24, 26–33, 35, 36, 42, 43, 73–82, 85–87, 89–94, 101, 103, 104, 107, 108, 110, 111, 115, 116, 118, 120, 123, 124, 128, 131, 141, 145, 130, 157–164, 168, 170, 172–174, 177, 178, 184, 191, 192, 194, 196–200, 207, 208, 210–212, 214, 221, 227, 238–240, 242, 244, 246, 247, 261, 262, 268–271, 274–279, 281–298, 299, 308–315, 320, 324, 326, 337, 343, 346, 351, 354345Defects in safety production rules and regulations and operating proceduresW2-3, W315, 16, 18, 23, 24, 37, 39, 42, 43, 46, 80, 82, 84–87, 90–94, 96–100, 102–105, 107–115, 120–125, 128, 131–134, 137–148, 130, 150, 151, 157, 158, 164, 165, 167–170, 172–175, 177, 178–184, 189, 191–193, 201, 203, 205–208, 213, 214, 216–224, 232–236, 238–240, 242, 245–247, 251–253, 258, 260, 254, 265, 267, 268, 270, 274, 275, 279, 281–289, 307, 310, 312, 313, 316–318, 321, 325, 337, 343, 352346Improper data managementF2-1, F2-3.716, 17, 26, 38, 42, 43, 71, 72, 79, 118, 162, 197, 199, 205, 207, 208, 215, 216, 237, 274, 299, 309, 315, 320, 321, 324, 327, 343, 352347Insufficient or wrong hydrological and geological dataF2-116, 17, 26, 38, 42, 43, 71, 72, 79, 118, 162, 197, 199, 205, 207, 208, 215, 216, 237, 274, 299, 309, 315, 320, 321, 324, 327, 343, 352348Improper quality acceptanceF2-3.4, F2-119, 60, 62–70, 135, 136, 156–158, 167, 183, 190–193, 200, 231, 232, 234, 238, 239, 253, 267, 307, 310, 312, 313351Improper maintenanceW2-5, W1160, 62, 64–70, 156–158, 167, 183, 190–193, 231–234, 238, 239, 253, 254, 265, 267, 307, 325352Design defects of emergency planW2-5, W819, 60, 62, 156, 190, 191, 195, 231, 232354Insufficient emergency plan drillsW2-5, W819, 60, 62, 156, 190, 191, 195, 231, 232Personnel subsystem355Insufficient experience in personnel or organization qualification problemsF2-1, W8, W11, W2-314–18, 23, 24, 26, 31, 35, 36, 38, 44, 71, 72, 74–76, 79, 82, 61, 96–116, 121, 123–134, 137–149, 159–164, 166, 168–173, 174–178, 179–180, 184–189, 196–199, 201–224, 235–237, 240, 242, 245–252, 260–263, 268–272, 274–279, 281–294, 297–298, 299, 308–324, 326, 328–337, 343, 346–354


### 3.2. Identification Result

Based on the EIMTSH, the seepage hazards of tailings pond are systematically identified. In this paper, 313 seepage hazards of tailings ponds are identified and 1912 relationships among them are shown in Table1 [31]. In the first column of Table 1, the names of eight subsystems of seepage system of tailings pond are listed. The fourth column is the hazard identified by the EIMTSH, which is given as the number in the third column. The second column indicates the specific category of the seepage subsystem of tailings ponds to which the fourth column of hazards belongs. The fifth column indicates that the hazard in the fourth column of the same row is identified by the supporting evidence, and the type and location of the evidence are marked. The details of the evidence are shown in Appendix. The last column is the hazard number, which indicates the hazard or event directly caused by the hazard in the fourth column of the same row.Take hazard 77 (The tailings dam slope ratio is unreasonable) as an example, the number of this hazard is 77, which belongs to the dam body class of the dam system. Based on the evidence F1-4.5, W4, and W7, we can confirm the existence of hazard 77 and find that hazard 77 can directly cause hazards 62, 64, 65, 73, and 157. Evidence F represents laws, standards, and norms, and W represents the scientific literature and accurate case. F1-4.1 indicates that the evidence is located in the first section of Chapter IV of ‘Code for Design of Tailings Facilities (GB 50863–2013)’. More detailed supporting evidence information is provided in appendix A, B, and C.


## 3.1. Identification Method

A hazard may cause loss of life, injury, or other health impacts, property damage, social and economic disruption, or environmental degradation [28]. In this paper, according to the characteristics of the tailing pond seepage system with the dynamic change of tailing pond life cycle, combined with industry laws and regulations and technical specifications, the seepage hazards of tailing ponds are divided into three modes or three states from the perspective of safety production. The first state is the dormant hazard, which is the initial factor or event to cause the seepage. It is an indirect factor and cannot be triggered by other factors or events. Its state is basically stable. The second is the armed hazard, which refers to the intermediate state of hazard evolution. It may evolve from the dormant hazard, or other armed hazards may cause it [29]. The third is the active hazard, which mainly refers to the seepage events that are happening [29].The causes of seepage accidents in tailings pond are complex, and the seepage system changes continuously with the life cycle of tailings pond. These characteristics make it difficult to identify the seepage hazards in tailings ponds. Although some scholars have proposed a series of hazard identification methods for such dynamic complex systems, these methods are mainly based on the experience and subjective judgment of the identification personnel. The result is that some key hazards may be missed [30]. In order to overcome the above shortcomings, this paper proposes a method to identify the seepage hazards of tailings pond, which is called the evidence-based identification method of three-dimensional seepage hazards (EIMTSH), as shown in Figure 2.Figure 2
The evidence-based identification method of three-dimensional seepage hazards.It can be seen from Figure2 that the EIMTSH includes three dimensions and each point in the space specifically represents the seepage hazards and influencing factors at each life cycle stage of tailings ponds under different supporting evidence. The Y-axis is composed of eight subsystems of the tailings pond seepage system, mainly including pond area subsystem, personnel subsystem, conveyor subsystem, drainage subsystem, monitoring subsystem, dam subsystem, material subsystem, and management subsystem. Each subsystem can be divided into different modules according to its function and structural characteristics. The Z-axis is the life cycle stage of tailings pond, which mainly includes construction stage, operation stage, closing stage, and reclamation stage or recovery stage. The division method of Z-axis and Y-axis is used to divide all the objects that need to be identified at different time periods and in different subsystems [29]. The X-axis is the supporting evidence used to identify the potential seepage hazards of tailings ponds, mainly including the relevant technical specifications and laws and regulations, seepage accident cases, literature, news media information, etc., as shown in Appendix A, B, and C [29].In order to find out all the seepage hazards, the paper analyzes the Code for Design of Tailings Facilities (GB 50863-2013), Code for Construction and Acceptance of Tailings Facilities (GB-T 50864-2013), and other evidence in Appendix A and then extract the hazards and the influence mechanism between hazards in each content one by one [29]. At the same time, referring to the content in Appendix B and Appendix C, we can get all the hazards of the seepage system in tailings ponds that has not been integrated, that is, all the spatial nodes in Figure 2. After integrating these identified hazards, all hazards of the seepage system in tailings ponds can be obtained, as shown in Table 1.Table 1
List of seepage hazards in tailings pond.
Tailings dam subsystemModules of the subsystemNumber (v)Hazard nameEvidenceNumber of hazards causedPond area subsystemPond environment2FloodW1-1.2.1, W6, W7, W8, W97, 19, 60, 62, 64, 65, 66, 67, 69, 150, 151, 156, 158, 167, 190, 191, 192, 193, 195, 273, 3253Ice and snowF2-3.4, W719, 67, 112, 181, 1954Strong windW5, W1-3.4.47, 19, 66, 3255Heavy rainfallW5, W9, W4, W6, W7, W8, F4, C2, C11, C1319, 67, 69, 150, 151, 193, 1956Extreme temperature changesW1-3.4.4, W719, 62, 65–67, 191, 232, 267, 3257SurgeW6, W1-3.4.4, F1-4.2, W6, C3, C1162, 65–67, 69, 150, 151, 190, 1938Beyond standard earthquakeW5, W2-3, W9, W11, W12, W4, W6, F419, 60, 62, 64–66, 70, 136, 150, 151, 191, 192, 232, 267, 273, 3259MudslideW2-2, W10, W83910Gravel foundationF1-4.1, W2-3, F315711Liquefied soil, soft clay, and collapsible loess foundationF1-4.1, W2-3, F3, C268, 70, 135, 136, 15712Water burst in the tailings pondF1-5.7, W2-3, F3127, 15813Karst cave or existence of mine shaftsF1-4.1, W2-3, F368, 135, 136, 15814Insufficient geological explorationW1-3.4.4, W6, F4, F389, 12115Failure to do engineering geological weaving and surveying during excavation and tunnelingW1-3.4.4, F5, F4, F334716Failure to predict and forecast engineering geological problems that may occur during constructionW1-3.4.4, F5, F4, F312117Inadequate research on adverse geological problems and improper handling measuresW1-3.4.4, F4, F319, 12118No engineering geological and hydrogeological surveys were carried out when the tailings dam reached the corresponding heightW1-3.4.4, F5, F319, 121, 34719Landslides in the tailings pondF6, W1-3.4.4, W9, W10, W67, 39, 19520The overburden of the bank slope connected to both ends of the tailings dam is thinW1-3.4.4, F315821The rock on the bank slope is broken, joints are developed, or faults pass throughW1-3.4.4, W8, F319, 15822Animals burrow, camp, and graze illegallyW1-3.4.3, W1-3.4.419, 64, 66, 150, 151, 15823Private digging in the tailings impoundmentW1-3.4.4, W2-3, W619, 64, 66, 150, 15124Illegal soil borrowing behind the damW1-3.4.4, W2-3, W664, 66, 15725There are mining activities near the siteF1-3.1, W2-3, W619, 62, 64, 6626Inappropriate selection of pond locationF1-3.1, W11, F310–13, 20, 21, 25, 32–34, 52, 208Selection of pond location31Open pits and depressions reserve tailings without special safety demonstrationF1-3.113532Insufficient impoundment length (upstream wet tailings impoundment)W1-1.1.13933The dam site is not conducive to the layout of drainage structuresF1-6.1, C820034Large catchment areaW2-2, W2-3, W8195Tailings pond construction35Unreasonable multidatabase phased construction planF1-139, 19436No operation plan for the joint impoundmentF1-139, 19437Overdue service of tailings pondF1-7, W9, W11, W5, W839, 65-66, 70, 73, 183, 191–193, 232–23438Inaccurate storage capacity calculationF1-3.239, 19439Insufficient storage capacity of tailings pondF1-3.2, W919042No antifreeze measures have been taken for tailings facilitiesF1-10, F1-1166, 112, 191, 232, 24443Antifreezing measures have not been finished before freezingF1-1066, 112, 191, 232, 24444Blasting construction does not meet the technical specificationsF2-4.2, W619, 62, 64–66, 191Material subsystem45Tailings particle size/gradation does not meet the requirementsW1-3.5.2, W9, F347, 48, 50, 51, 66, 68, 61, 23446Excessive flow of tailings slurryF1-11, W1-3.5.250, 61, 233, 234, 26747Excessive tailings unit weightW1-3.5.2, C251, 52, 68, 61, 23348Concentration and consistency of tailings slurry do not meet the requirementsF1-11, W1-3.5.250, 51, 68, 61, 233, 23449Strongly corrosive tailingsF1-11, W1-3.5.2, W12, C3, C9233, 23850Tailings are highly abrasiveF1-11, W1-3.5.223351Unqualified dry beach-covering materialsW1-3.4.453, 157, 158, 19552Unqualified filling materialsF2-3.364–68, 70, 73, 135, 136, 15753Erodible tailings exposureW1-3.4.4, C3, C5, C6157Dam subsystemDam body63Decrease of dam elevationW6, W11, W6, C239, 190, 19465Dam deformationW1-3.4.5, W8, C262, 64, 157, 267, 27366Dam crackF6, W1-3.6.6, W6, W7, C8, C11–C1362, 64, 73, 15867Dam surface water saturationW2-3, W3, W662, 64–66, 73, 15768Uneven settlement of the damW1-3.6.6, W6, C962–66, 191, 192, 267, 27369Scouring of the damW6, W2-3, W6, W7, C11, C1362, 64–6670Tailings liquefactionF1-4.4, W1-1.1.4, W8, W962, 64, 68, 136, 156–15871Defects in seismic calculation of tailing pondF1-4.47272Improper seismic designF1-4.4, W862, 64, 66, 70, 73, 135, 13675Improper calculation method of tailings dam stabilityF1-4.4, W464, 73, 77–81, 89, 90, 92–9477The tailings dam slope ratio is unreasonableF1-4.5, W4, W762, 64, 65, 73, 15778Unreasonable width of dam crestF1-4.5, W462, 64, 65, 15779Improper dam type selection for the initial damW1-1.1.239, 64, 15780The height of initial dam is unreasonableF1-4.1, W939, 64, 65, 73, 81, 88, 19481The ratio of the initial dam height to the total dam height of the upstream tailings dam is unreasonableF1-4.1, W964, 65, 7382The dam layout is unreasonable (the location of subdam and primary dam)F1-4.1, C232, 39, 69, 73, 13561Poor control of tailings depositsW1-1.1.364, 65, 68, 77, 152, 154, 155, 15783The rising speed of tailings between dam downstream and upstream is unbalancedW1-1.1.36184The rising speed of the dam does not meet the requirements of the rising speed of the sedimentary beachW1-1.1.380, 61, 85, 8685The accumulation dam is too highF1-4.1, F562, 64, 65, 8186The height of the accumulation dam is lower than the height of tailings accumulationF1-4.1, F539, 65, 88, 190, 19487Defects in the layout of maintenance passages of the primary damF1-4.5, F565, 66, 8288The requirements for discharge under ice cannot be met in frozen areasF1-4.111289The upstream method is used to build dams on the seismic zoneF1-4.160, 62, 7090Fine-grained tailings dams using the direct methodF1-4.164, 65, 6191Unreasonable setting of tailings dam bermF1-4.565, 66, 8292The tailings dam is not equipped with antiscouring measuresF1-4.6, F569, 8293No filtration water and sediment storage dams are built in the centerline and downstream tailings damsF1-4.664, 8294Unreasonable height of the filtration water and sediment storage damsF1-4.639, 64, 6595Defects of step arrangement on the outer slope of accumulation damF1-3.465, 66, 82Dam filling96Use of only one tailings discharge point for a long timeF1-3.4, W2-361, 86, 15297Long time no replacement of tailings discharge pointF1-3.4, W2-361, 86, 15298The tailings discharge method does not match the direction of advancementF1-3.4, W2-361, 15299The branch pipes that discharge tailings are opened too littleF1-3.4, W2-361, 152, 234100Failure to evenly discharge tailingsF1-3.4, W2-361, 86, 152101Unreasonable layout of ore branch pipeF1-3.461, 86, 88, 152, 234102Layered filling and layered compaction are not carried outF2-3.4, F564–66, 68, 77103Improper method of sectionalized filling and rollingF2-3.4, F564–66, 68, 77, 122104Unreasonable slope of the top surface of layered rollingF2-3.4, F564–66, 68105The tailings discharged into the pond are not leveled and rolledF2-3.4, F586106Improper selection of tailings leveling and compaction equipmentF2-3.4, F577, 104, 122107Rolling is perpendicular to the dam axisF2-3.4, F565, 66, 104108Laying the upper layer of new materials before the dam body is qualifiedF2-3.4, F565, 66, 68, 104, 122, 158109The filling and rolling of the cohesive tailings dam is not continuousF2-3.4, F565, 66, 68, 104, 122110Improper pavingF2-3.4, F564–66, 68, 104111Downhill paving when the ground is unevenF2-3.4, F564–66, 68, 104112The dam is filled with ice, snow, or other debrisF2-3.4, F564–66, 68, 158113Improper unloading methodF2-3.4, F565, 66114Filling and slope adjustment are not carried out at the same timeF2-3.4, F564, 66, 77115Construction machinery and personnel crossing the dam surface in violation of regulationsF2-3.4, F565, 66116Resuming work in violation of regulationsF2-3.4, F5112117The maintenance platform in downstream dam slope is defectiveF2-3.465, 66, 73, 122118Unreasonable determination and modification of dam construction indicatorsF2-3.464, 77, 78120The subsidence allowance of the dam filling is unreasonableF2-3.465, 66, 158121Improper handling of dam-bank junctionW1-3.4.465, 66, 73, 158122There is a horizontal weld on the slopeF2-3.664, 66, 73124Slope cutting did not follow the design requirementsF2-3.6, F519, 64, 65125Slope protection was not carried out in timeF2-3.6, F519, 62, 64, 65, 73, 122126Unreasonable design of cast-in-place protective surfaceF2-3.619, 62, 64–66, 73, 77, 122, 157127When the dry storage method is adopted, the accumulated water in the pond area is not discharged in timeF1-564, 67128Mixing dry and wet tailings when using dry storageF1-564, 65, 68129Tailings pond of insufficient depth and water resources chooses wet storageF1-539Dam foundation131Poor construction quality of vertical antiseepage facilitiesF2-3.266, 157, 165132No effective filter layer is set on the dam foundationW1-3.4.4131, 157, 165133The concrete cutoff wall is not on the fresh bedrockF2-3.2131, 157, 165134Inadequate protection measures after dam foundation excavationF2-3.266, 131, 135, 136135Uneven foundation subsidenceW1-1.4, W963–66, 68, 73, 136, 191, 267, 273136Dam foundation instabilityF4, F6, W1-1.4, W11, W12, W8, W964–66, 68, 73137The protective layer reserved has not been removed before filling when the natural clay is used as the dam foundationF2-3.2, F5131, 133, 135, 136, 158138No measurement and set-up before clearing dam foundationF2-3.2, F5131, 133, 135, 136, 165139Untreated strong weathered layer and broken zone of rock foundationF2-3.2, F5131, 133, 135, 136, 158140Improper handling of the alluvium above the bedrockF2-3.2, F5131, 133, 135, 136, 158141Irregular grouting work for dam foundation treatmentF2-3.2, F5131, 135, 136, 157Dry beach145No coverage measures in the pond areaW1-3.4.453, 157146The main dam has not been reclaimed and greened in timeF1-5.753147Insufficient soil cover or greening on the dam slope (dry)W1-3.4.4, F1-5.753148Weakness of paving has not been reinforcedW1-3.4.4, F5158130Poor construction quality of horizontal pavingW1-3.4.4157149The length or thickness of the horizontal paving in front of the dam is insufficientW1-3.4.4157150Natural paving (covering) is destroyedW1-3.4.4158151The protective layer (cover) of the dry beach is destroyedW1-3.4.453, 158152Poor deposition control for dry beach faceW1-3.4.4, F4154, 155, 157154The minimum dry beach length does not meet the requirementsF1-4.2, W864, 167155The minimum free height does not meet the requirementsF1-4.2, W864, 167Seepage156Leakage damageF6, W1-3.4.4, W2-3, W8, W9, W11, W12, C1-C1360, 62, 64157Filter failureW1-3.4.4, W864, 67, 136, 156, 167, 195158Leakage channelW1-3.4.4, W8, C1, C5, C9-C10, C12-C1364, 68, 135-136, 156159No special seepage simulation experiments were done for the 1st and 2nd level tailings dams according to the terrain conditionsF1-4.393, 162, 167160The seepage calculation of the dam body was not carried out in the preliminary design stageF1-4.393, 162, 167161The expanded or heightened tailings pond did not carry out the dam seepage calculationF1-4.3162, 167162Unreasonable antiseepage designW1-3.4.467, 156-157164The dam foundation area between the initial dam and sediment storage dam is not equipped with drainage facilitiesW1-3.4.4157165Defects of dam foundation drainage facilitiesW1-3.4.4157166Inaccurate confirmation of critical and control seepage linesF1-4.3167167Seepage line is higher than control seepage lineF1-4.3, W11, W3, F4, C165–67, 154–156168Improper measures to reduce the seepage lineF1-4.3167169Improper construction connection of impermeable geosyntheticsF2-4.3157, 165, 184170Insufficient protection measures for seepage prevention facilitiesF2-11158, 165, 183171Improper selection of soil for the soil cushionF2-11157, 165, 184172Unqualified soil pad compactionF2-11157, 165, 184173Improper laying of geomembraneF2-11, F4157, 165, 184365The HDPE geomembrane did not conduct visual inspection and physical performance index testing before layingF5-11.3173366The laying amount of HDPE geomembrane exceeds the amount of welding that can be completed in one working dayF5-11.3173367When laying the HDPE geomembrane, unfold first and then dragF5-11.3173368Improper windproof measures of HDPE geomembraneF5-11.3173369After the HDPE geomembrane was laid, no welding was carried out within the specified timeF5-11.3173370Welding seam and welding inspection and quality control are not carried out in the HDPE geomembrane layingF5-11.3173371The vehicle is rolled directly on the HDPE geomembrane and the HDPE geomembrane is damagedF5-11.3173372The laying of HDPE geomembrane does not allow for expansion and contraction of the materialF5-11.3173174Unqualified geomembraneF2-11157, 165, 184175No drainage measures under the geomembrane protective layerF2-11157, 165, 184176Poor drainage of composite geotechnical drainage networkF2-11157, 165177Improper installation of composite geotechnical drainage networkF2-11157, 165, 176, 183178Improper construction of sodium bentonite matF2-11157, 165, 184360The sodium bentonite pad appears wrinkled and suspendedF5-11.5178361Personnel and vehicles rolled on on the sodium bentonite padF5-11.5178362Improper repair materials and scope for damaged parts of sodium bentonite padF5-11.5178363Construction of sodium bentonite pad under rain and snowF5-11.5178364The construction of sodium bentonite mat shows a crossF5-11.5178179The materials are poured down from the top of the slopeF2-3.5184180People walking, rolling stones, and handling other materials on the paved filter layerF2-3.5183181Ice and snow and debris are mixed in the filter materialF2-3.5182182Unqualified filter materialF2-3.5183183Filter failureF2-3.5, W2-3, W3, F465, 157, 165184Unqualified filter layer pavingF2-3.5, F466, 183186Improper laying of geotextileF2-3.5165, 184187Geotextile cloggedF2-3.5165, 183188The geotextile is exposed to the sun for a long timeF2-3.5165, 183189Unreasonable geotextile designF2-3.5165, 183Drainage subsystemDrainage plan190OvertoppingF6, W2-3, W9, W12, W11, F4, C1, C3, C1160, 62, 64, 69191Fracture of drainage structureW1-3.4.4, F466, 69, 127, 158, 192, 200192Leaking drainage structureW1-3.4.4, F4, C766, 67, 69, 127, 150, 151, 158, 195, 200193Scour or cavitation drainage structuresW1-3.4.4, F4191, 192194Insufficient regulating water storageW1-3.4.439195Rapid rise of pond water levelW1-3.4.4, W2-3, C2, C139, 65, 67, 152, 154, 155, 167, 190, 194196No drainage facilitiesF1-6.1127, 195, 200197The foundation pit at the higher groundwater level has no drainage facilitiesF1-6.1195, 200198The flood drainage system does not match the dam construction methodF1-6.3, F4191, 200199The determination of the flood control standard of the tailing pond is not accurateF1-6.1127, 190, 194, 200200Insufficient flood discharge capacityF1-6.2, F6, W9127, 193, 195201Blocking defects of flood drainage facilitiesF1-6.3192, 193, 195, 200202Unreasonable temporary flood control plan during construction periodW1-3.4.4195, 200203Improper diversion measuresW1-3.4.4195, 200205The installation location and elevation of drainage facilities do not meet the design requirementsF1-6.1, F4193, 195, 200206Insufficient elevation of drainage holes in front of the damF1-6.1200207Flood drainage structures are directly located on the tailings sediment beachF1-6.1, F4191208The foundation of the flood drainage structure is set in the area with poor engineering geologyF1-6.1191209Insufficient foundation bearing capacity of underground flood drainage structuresF1-6.1191210Improper installation of flood interception and drainage facilitiesF1-6.1, F4191, 200211The dry tailings pond of third-class and above adopts flood interception ditch for flood dischargeF1-6.1, F4200212Drainage facilities are not located in front of the blocking damF1-5.6193213Use of mechanical flood drainageF1-6.2200214The on-site line setting is inconsistent with the construction drawingF2-3.177, 78, 205, 210, 237, 273, 274215Confluence calculation is not accurateF1-6.2, F4195, 200216Use of unproven non-24-hour rainfall durationF1-6.2215218Improper installation of energy dissipation facilitiesF1-6.3191, 193219No energy dissipation measures have been taken in the tailings facilityF1-6.3191, 193220The maximum flow rate of flood is greater than the allowable flow rate of the building materialsF1-6.2191, 193Backwater plan221The clarified water of the tailings pond is not used for backwater utilizationF1-9, F4195222One-sided pursuit of backwater qualityW1-3.4.3, W8, F4195224Low tailings water recovery rateF1-9195227Insufficient volume of backwater pondF1-9224Conveyor subsystemConveying facilities231Leaks in transmission facilitiesF6, W1-3.4.4, W8, C469, 61, 150–152232Broken conveying facilitiesW1-3.4.4, W1269, 100, 231, 253233Scour or cavitation transportation facilitiesW1-3.4.4232, 238-239234Blockage or siltationW1-3.5.2100, 165, 176, 191, 195, 200, 232, 253235No overload alarm signal and protection deviceF1-1046, 191, 233-234, 239236No flow and pressure detection instrumentF1-1046, 191, 233-234, 239237The installation location and elevation of the transportation facilities do not meet the design requirementsF2-10234238Serious corrosion of equipmentW1-3.4.4, W11, W12191, 231-232, 253, 325239Serious wear and tear of conveying facilitiesW1-3.4.4231-232, 253240No anticorrosion treatment in tailings facilitiesF1-6.3, F2-5.3, W9233, 238, 244241Unqualified anticorrosion materialsF2-5.3193, 233, 238, 244242Improper anticorrosion constructionF2-5.3, W11193, 233, 238, 244244Incident pool defectW1-3.5.5231245Improper installation of the instrument of the thickenerF1-10, F446–48, 233, 238, 239246Unreasonable area of thickening tankW1-3.5.5, F2-10, F4250247The height of the thickening tank is unreasonableW1-3.5.5, F2-10, F4231, 250248Improper selection of thickening tankW1-3.5.5, F2-10231, 250249Improper selection of the inclined plate and inclined pipeW1-3.5.5231-232, 238-239, 250250Insufficient production capacity of the thickenerW1-3.5.5234251The pipelines and valves of the conveying equipment are not connected tightlyF2-10, F4231, 238, 239, 253252Flocculant preparation and addition do not meet the requirementsF1-1047-48, 234, 253253Concentration equipment failureF2-1047-48, 231, 234, 250258Waste mixed into tailings slurryW1-3.5.247–50, 65, 112, 233-234, 238-239, 253, 267260Improper handling of local hydraulic phenomenaW1-3.5.2233-234, 238-239, 267261Unreasonable selection of classification equipmentW1-3.5.545, 254, 264262No spare grading equipmentW1-3.5.5264263The pressure of the cyclone to feed the tailings is unstableW1-3.5.545, 233, 239254Damaged grading equipmentW1-3.5.545, 231, 234, 263, 264264Insufficient cyclone production capacityW1-3.5.5234265Damaged dredgerW1-3.5.5234266Insufficient production capacity of dredgerW1-3.5.5234Other transportation facilities267Pipes and grooves deformationF2-5.3191, 193, 232, 234, 239268Defects of the interception ring the in pipe bodyF2-5.369, 192, 193269The pipe body is in direct contact with the big rocksF2-5.3191, 232, 267270The outer wall of the pipe is not protectedF2-5.3191, 232, 267271The dimensions of pipes, grooves, tunnels, etc. do not meet the requirementsF1-6.3, W1-3.5.2191, 193, 234, 267272Pipes and grooves material unqualifiedF1-11, F4191, 193, 232, 267273Subsidence or deformation of supporting facilities such as pipes, trenches, and tunnelsF1-11, F2-4.3191, 232, 267274Improper installation of supporting facilitiesF1-11,F2-4.3191, 232, 267, 273275Excessive slope deviation for laying pipes, trenches, tunnels, etc.F1-11, W1-3.5.2191, 193, 233, 234, 239, 267276Improper design of corners of pipes, grooves, tunnels, etc.F1-11191, 193, 233, 234, 239, 267277Improper subgrade design of pipes and groovesF1-11193, 233, 234, 239278Improper design of slope ratio of pipe trench and embankmentF1-11, F4193, 239279The pipe opening was not closed when the pipeline installation and laying were suspendedF1-11192280Pipes and grooves failed the pressure testF1-11, F2-8.4191, 232, 267281Poor quality of fill around the pipelineF1-11191, 267282The axial filling height of the pipe in the dam body is differentW1-3.4.4191, 267283Improper rolling of the backfill on the top of the facilityW1-3.4.4191, 267284Improper pipe weldingF1-6.3191, 192, 233, 251, 267285No settlement joints between pipe and wellF1-6.3191, 233, 267286The joint length of the drain pipe is unreasonableF1-6.3191, 192, 233, 267287Deformation joints are not provided at both ends of the drain pipe according to the design requirementsF1-6.3191, 233, 267288Lax masonry of pipe wallsF2-5.2192, 232, 233, 251289Improper excavation (pipes, trenches, tunnels, etc.)F2-4.2, F2-5.265, 66, 87, 91, 95, 117, 120, 131, 133, 191Pump293Pump selection does not meet the requirementsF1-12, W1-4.446, 195, 200, 232, 234, 307294Insufficient capacity of pumping station designF1-9, F1-12195, 200296Poor pump qualityF1-12, W1-4.4192, 193, 233, 234, 239, 307297Unreasonable valve selection in pumping stationF1-12, W1-4.4192, 234, 251, 307298Improper pump station configurationF1-12, W1-4.446, 192, 195, 234, 307378There are no flow and pressure detection instruments in the pumping stationW1-4.4298379Defect of buffer device in pumpW1-4.4298380Defects of the slurry pipeline in the pumping stationW1-4.4298299Improper installation of pumpsF1-11, W1-4.4192, 195, 200, 233, 234, 307307Pump failureF1-11, W1-4.461, 100, 127, 192, 195, 200, 231373No liquid can be discharged from the sand pumpW1-4.4307374Insufficient liquid output from sand pumpW1-4.4307375Pump consumes too much powerW1-4.4307376Pump bearing heatW1-4.4307377Deformed or broken pump shaftW1-4.4307308Closure design not in accordance with regulationsF1-6.3, W5, F419, 37, 62–70, 73, 135, 136, 148, 157, 158, 167, 183, 191, 192, 232, 234, 238, 254, 265, 267, 273, 307, 314309The tailings pond are closed without understanding the hidden dangers and risksF1-7, W5, F4, F366, 310, 312, 313310The surrounding environment improvement does not meet the requirementsF1-7, W519312Dam body renovation does not meet the requirementsF1-7, W562–70, 73, 135, 136, 148, 157, 158, 167, 183,313The improvement of flood discharge system does not meet the requirementsF1-7, W5191, 192, 195, 234, 267, 273, 307314No plans for reclamation and ecological restoration after closure designF1-7, W5, F419315Unreasonable reclamation planW2-5, W8, F419, 310, 312, 313316Simultaneous mining and discharge of tailings in a tailings pondF1-8, F465, 66, 68, 61, 151, 152, 157, 158, 191, 232317The upstream wet-stacking tailings pond adopts the recovery method advancing from the embankment to the pondF1-864–66318Mechanical excavation of tailings near drainage facilitiesF1-8191, 192, 267, 273320Unreasonable tailings recovery planF1-8, F464, 151, 157, 158, 191, 192321Stability analysis and safety measures of the tailings dam and the slope is insufficientF1-819, 64, 73Monitoring subsystem324Improper selection of monitoring instruments and equipmentF1-3.4, W8, F4, C2235, 327, 343325Monitoring instrument failure and work interruptionF1-3.4, W8, C2327, 343326The third-class and above tailings ponds are not equipped with monitoring facilities that combine manual and automatic monitoringF1-3.419, 22–24, 154, 155, 231, 327327Safety monitoring facilities cannot fully reflect the operating status of the tailings pondF1-3.4, C27, 19, 22–24, 37, 45–50, 65–69, 135, 136, 191, 192, 200, 267, 343328No monitoring points are arranged outside the dam toeW1-3.4.519, 22, 23, 231, 310, 327329No additional monitoring facilities are installed at the dam abutment, bedrock faults, and buried pipes in the damW1-3.4.565–69, 135, 136, 191, 192, 267, 327330No monitoring of the amount and composition of tailings entering the pondF1-3.445–50, 327331No external drainage and composition monitoringF1-3.4200, 327332No monitoring of groundwater and surrounding water bodiesF1-3.4327334The number of water quality monitoring wells around the tailings pond is insufficientF1-3.4327336The setting of monitoring facilities is not included in the construction planF2-3.7325, 327337Improper safety monitoring during tunnel excavationF2-6.1214, 271, 273–276, 289, 327Management subsystem339Insufficient capital investmentW2-3, W314–18, 24, 31, 37, 42, 52, 89, 90, 92, 93, 132, 134, 145–148, 159–161, 164, 196, 197, 221, 235, 236, 240, 268, 293, 294, 308, 310, 312, 324, 326, 328–334, 351,340Insufficient safety supervisionW2-3, W11, W12, W5, C47, 14–19, 22–24, 26, 31, 36, 37, 42–52, 60, 62–70, 73, 74, 76–173, 174–178, 179–214, 218–298, 299, 307, 308–337, 346, 348, 351–355343Inadequate safety evaluationW2-3, W3, W519, 31, 60, 156, 190, 200, 224, 231, 327344Outdated specifications and standards for survey, design, construction, and acceptanceW2-3, W314–18, 23, 24, 26–33, 35, 36, 42, 43, 73–82, 85–87, 89–94, 101, 103, 104, 107, 108, 110, 111, 115, 116, 118, 120, 123, 124, 128, 131, 141, 145, 130, 157–164, 168, 170, 172–174, 177, 178, 184, 191, 192, 194, 196–200, 207, 208, 210–212, 214, 221, 227, 238–240, 242, 244, 246, 247, 261, 262, 268–271, 274–279, 281–298, 299, 308–315, 320, 324, 326, 337, 343, 346, 351, 354345Defects in safety production rules and regulations and operating proceduresW2-3, W315, 16, 18, 23, 24, 37, 39, 42, 43, 46, 80, 82, 84–87, 90–94, 96–100, 102–105, 107–115, 120–125, 128, 131–134, 137–148, 130, 150, 151, 157, 158, 164, 165, 167–170, 172–175, 177, 178–184, 189, 191–193, 201, 203, 205–208, 213, 214, 216–224, 232–236, 238–240, 242, 245–247, 251–253, 258, 260, 254, 265, 267, 268, 270, 274, 275, 279, 281–289, 307, 310, 312, 313, 316–318, 321, 325, 337, 343, 352346Improper data managementF2-1, F2-3.716, 17, 26, 38, 42, 43, 71, 72, 79, 118, 162, 197, 199, 205, 207, 208, 215, 216, 237, 274, 299, 309, 315, 320, 321, 324, 327, 343, 352347Insufficient or wrong hydrological and geological dataF2-116, 17, 26, 38, 42, 43, 71, 72, 79, 118, 162, 197, 199, 205, 207, 208, 215, 216, 237, 274, 299, 309, 315, 320, 321, 324, 327, 343, 352348Improper quality acceptanceF2-3.4, F2-119, 60, 62–70, 135, 136, 156–158, 167, 183, 190–193, 200, 231, 232, 234, 238, 239, 253, 267, 307, 310, 312, 313351Improper maintenanceW2-5, W1160, 62, 64–70, 156–158, 167, 183, 190–193, 231–234, 238, 239, 253, 254, 265, 267, 307, 325352Design defects of emergency planW2-5, W819, 60, 62, 156, 190, 191, 195, 231, 232354Insufficient emergency plan drillsW2-5, W819, 60, 62, 156, 190, 191, 195, 231, 232Personnel subsystem355Insufficient experience in personnel or organization qualification problemsF2-1, W8, W11, W2-314–18, 23, 24, 26, 31, 35, 36, 38, 44, 71, 72, 74–76, 79, 82, 61, 96–116, 121, 123–134, 137–149, 159–164, 166, 168–173, 174–178, 179–180, 184–189, 196–199, 201–224, 235–237, 240, 242, 245–252, 260–263, 268–272, 274–279, 281–294, 297–298, 299, 308–324, 326, 328–337, 343, 346–354


## 3.2. Identification Result

Based on the EIMTSH, the seepage hazards of tailings pond are systematically identified. In this paper, 313 seepage hazards of tailings ponds are identified and 1912 relationships among them are shown in Table1 [31]. In the first column of Table 1, the names of eight subsystems of seepage system of tailings pond are listed. The fourth column is the hazard identified by the EIMTSH, which is given as the number in the third column. The second column indicates the specific category of the seepage subsystem of tailings ponds to which the fourth column of hazards belongs. The fifth column indicates that the hazard in the fourth column of the same row is identified by the supporting evidence, and the type and location of the evidence are marked. The details of the evidence are shown in Appendix. The last column is the hazard number, which indicates the hazard or event directly caused by the hazard in the fourth column of the same row.Take hazard 77 (The tailings dam slope ratio is unreasonable) as an example, the number of this hazard is 77, which belongs to the dam body class of the dam system. Based on the evidence F1-4.5, W4, and W7, we can confirm the existence of hazard 77 and find that hazard 77 can directly cause hazards 62, 64, 65, 73, and 157. Evidence F represents laws, standards, and norms, and W represents the scientific literature and accurate case. F1-4.1 indicates that the evidence is located in the first section of Chapter IV of ‘Code for Design of Tailings Facilities (GB 50863–2013)’. More detailed supporting evidence information is provided in appendix A, B, and C.


## 4. Propagation Network of Seepage Risk in Tailings Pond

### 4.1. Model Construction

In order to apply the complex network model to characterize the seepage risk evolution process of tailings pond, this paper uses the seepage hazard to represent the network node and the relationship between hazards represents the network edge. At the same time, according to the three states of seepage hazards mentioned above, the PNSRTP is divided into three-layer nodes (dormant hazard, threat hazard, and activity hazard/accident) and two stages (from dormant hazard to threat hazard and from threat hazard to activity hazard). In this paper, with the help of complex network software Pajek, the hazard and the relationship between hazards in Table1 are constructed as the PNSRTP, as shown in Figure 3.Figure 3
Model of the PNSRTP.In Figure3, the first layer of nodes constitutes dormant hazards, represented by yellow nodes, with a total of 31. Dormant hazards are the initial hazards that cause other hazards, which cannot be caused by others. Earthquakes, floods, strong winds, etc., are all dormant hazards. The second layer of nodes includes armed hazards, represented by orange, with a total of 279. The second-layer node can be formed by the evolution of the initial dormant hazard and can also be caused by other armed hazards. The evolution relationship between hazards is complex, such as slope ratio, rapid rise of pond water level, and high phreatic line. The third-layer nodes are active hazards, which are indicated by red nodes, indicating that the accidents are happening or have happened. The seepage system of the tailings pond mainly includes three types of accidents: overtopping, leaks in transmission facilities, and seepage damage.


### 4.2. Analysis of Network Statistical Characteristics

#### 4.2.1. Degree Values and Degree Distribution

The degree values of each node in the PNSRTP are shown in Figure4. The degree value of the seepage hazard node is an important index to reflect the influence of hazards. According to the different directions of the relationship between hazards, it can be divided into out degree and in degree. Through the calculation using Pajek software, the average degree of the PNSRTP is found to be 12.22 and the network density is 0.02. It shows that a node with potential seepage hazard is directly related to 12.22 hazards on average, but the overall density of the PNSRTP is not large.Figure 4
Node degree in the PNSRTP.As can be seen from Figure4, the node with the largest degree is 340 (insufficient safety supervision), which can directly affect 261 kinds of hazards. 355 (lack of qualification and experience of personnel and institutions) belongs to the personnel system, which is the second largest hazard (182). The degree values of 345 (defects of safety production rules and regulations and operation procedures) and 344 (outdated specifications and standards for survey, design, construction, and acceptance) are 145 and 136, respectively. The degree values of 65 (dam deformation), 66 (dam crack), and 191 (drainage structure fracture) are all 59, of which 65 and 66 belong to the dam system and 191 belongs to the drainage system. 157 (filter water failure) also belongs to the dam system, for which the degree value is 49. The degree value of 339 (insufficient capital input) is 45, which belongs to the management system with hazards 340, 344, and 345, which highlights that the management factor plays a vital role in the safety management of the tailings seepage system. The degree value of 234 (blockage or siltation) is 41, which is the smallest hazard in the top ten hazards and also the only hazard belonging to the conveying system. It shows that the conveying system also has a certain impact on the seepage of tailings pond.From the perspective of out degree, 340 (lack of safety supervision), 355 (lack of qualification and experience of personnel and institutions), 345 (defects in safety production rules and regulations and operating procedures), 344 (outdated specifications and standards for survey, design, construction, and acceptance), and 339 (insufficient capital investment) are the five biggest hazards, which are 261, 181, 145, 136, and 45, respectively. These hazards can easily trigger other hazards, which are important causes of seepage risk transmission. 65 (dam deformation), 66 (dam crack), 191 (drainage structure fracture), 157 (filter water failure), and 234 (blockage or siltation) are the five biggest hazards of in-degree value, which have degree values 58, 56, 53, 45, and 33 respectively. Because these are easily caused by other hazards, these hazards should be monitored and paid attention to in the prevention of seepage accidents.The cumulative degree distribution of the PNSRTP is shown in Figure5. The cumulative degree distribution presents a power-law distribution that has the approximate fit Pk=3.8428x−1.192 (R2=0.9468) [23]. The above result deviates from the power-law nature for lager k, which indicates that the PNSRTP has scale-free property [23]. The scale-free property shows that a few nodes have high degree values in the PNSRTP, which is consistent with the distribution of degree values in Figure 4. These nodes make the PNSRTP robust to random attacks. This is reflected in the fact that although the world’s major economies have invested a lot of resources in the safety management of the seepage system of tailings pond in the past, the seepage accidents of tailings pond often occur due to the inability to find out the key hazards (determine the importance of the hazards). At the same time, these high degree value nodes show vulnerability to specific attacks. If we can apply this characteristic to the treatment of seepage risk of tailings pond, determine the optimal treatment sequence of hazards, and block the correlation between hazards, the occurrence of seepage accidents will be greatly reduced.Figure 5
Cumulative degree distribution of the PNSRTP.


#### 4.2.2. Average Path Length and Network Diameter

According to Pajek calculation, the diameter of the PNSRT network is 13, which represents the longest distance between two hazard nodes in the network. The distance between node 9 (mudslide) and 224 (low tailings water recovery rate) or node 8 (beyond standard earthquake) and 207 (flood drainage structures are directly located on the tailings sediment beach) is 13. They are the node pairs with the farthest risk propagation distance in the network.The average path length of the PNSRTP is 4.90, which means that the seepage risk propagates from one hazard node to other hazard nodes in the network with an average of no more than 5 nodes. The PNSRTP has more than 300 hazard nodes and nearly 2000 hazard relationships, but the average distance between the two hazard nodes is very short. The above characteristics show that the cause of seepage risk is complex and the propagation speed is fast. When the seepage risk is formed, if effective measures are not taken to control and manage it in time, the seepage accident of tailings pond may be caused.


#### 4.2.3. Clustering Coefficient and Small-World Property

According to the definition of clustering coefficient, the node with degree value of 1 has no agglomeration. Therefore, when calculating the clustering coefficient of each node in the PNSRTP, the node with degree value of 1 is excluded. The clustering coefficient of each point in the PNSRTP is shown in Figure6. It can be seen from Figure 6 that the clustering coefficient of nodes is between 0 and 0.5. The clustering efficiency of hazards 83 (the rising speed of tailings between dam downstream and upstream is unbalanced) and 266 (insufficient production capacity of dryer) is 0.5. The clustering of other most nodes is between 0.05 and 0.35, and the distribution is more uniform. This reflects the aggregation of the PNSRTP around hazards 83 and 266.Figure 6
Clustering coefficient of nodes in PNSRTP.In order to determine whether the PNSRTP has the small-world property, this paper uses Pajek complex network software to generate a random network with the same number of nodes and average degree value as the PNSRTP, as shown in Figure7. After calculation, the average clustering coefficient of this random network is 0.04, which is far less than that of the PNSRTP (0.19). Combined with the fact that the average path length of the PNSRTP is less than 5, it can be concluded that the PNSRTP has the small-world property [32].Figure 7
Equal-sized seepage risk random network.


## 4.1. Model Construction

In order to apply the complex network model to characterize the seepage risk evolution process of tailings pond, this paper uses the seepage hazard to represent the network node and the relationship between hazards represents the network edge. At the same time, according to the three states of seepage hazards mentioned above, the PNSRTP is divided into three-layer nodes (dormant hazard, threat hazard, and activity hazard/accident) and two stages (from dormant hazard to threat hazard and from threat hazard to activity hazard). In this paper, with the help of complex network software Pajek, the hazard and the relationship between hazards in Table1 are constructed as the PNSRTP, as shown in Figure 3.Figure 3
Model of the PNSRTP.In Figure3, the first layer of nodes constitutes dormant hazards, represented by yellow nodes, with a total of 31. Dormant hazards are the initial hazards that cause other hazards, which cannot be caused by others. Earthquakes, floods, strong winds, etc., are all dormant hazards. The second layer of nodes includes armed hazards, represented by orange, with a total of 279. The second-layer node can be formed by the evolution of the initial dormant hazard and can also be caused by other armed hazards. The evolution relationship between hazards is complex, such as slope ratio, rapid rise of pond water level, and high phreatic line. The third-layer nodes are active hazards, which are indicated by red nodes, indicating that the accidents are happening or have happened. The seepage system of the tailings pond mainly includes three types of accidents: overtopping, leaks in transmission facilities, and seepage damage.


## 4.2. Analysis of Network Statistical Characteristics

### 4.2.1. Degree Values and Degree Distribution

The degree values of each node in the PNSRTP are shown in Figure4. The degree value of the seepage hazard node is an important index to reflect the influence of hazards. According to the different directions of the relationship between hazards, it can be divided into out degree and in degree. Through the calculation using Pajek software, the average degree of the PNSRTP is found to be 12.22 and the network density is 0.02. It shows that a node with potential seepage hazard is directly related to 12.22 hazards on average, but the overall density of the PNSRTP is not large.Figure 4
Node degree in the PNSRTP.As can be seen from Figure4, the node with the largest degree is 340 (insufficient safety supervision), which can directly affect 261 kinds of hazards. 355 (lack of qualification and experience of personnel and institutions) belongs to the personnel system, which is the second largest hazard (182). The degree values of 345 (defects of safety production rules and regulations and operation procedures) and 344 (outdated specifications and standards for survey, design, construction, and acceptance) are 145 and 136, respectively. The degree values of 65 (dam deformation), 66 (dam crack), and 191 (drainage structure fracture) are all 59, of which 65 and 66 belong to the dam system and 191 belongs to the drainage system. 157 (filter water failure) also belongs to the dam system, for which the degree value is 49. The degree value of 339 (insufficient capital input) is 45, which belongs to the management system with hazards 340, 344, and 345, which highlights that the management factor plays a vital role in the safety management of the tailings seepage system. The degree value of 234 (blockage or siltation) is 41, which is the smallest hazard in the top ten hazards and also the only hazard belonging to the conveying system. It shows that the conveying system also has a certain impact on the seepage of tailings pond.From the perspective of out degree, 340 (lack of safety supervision), 355 (lack of qualification and experience of personnel and institutions), 345 (defects in safety production rules and regulations and operating procedures), 344 (outdated specifications and standards for survey, design, construction, and acceptance), and 339 (insufficient capital investment) are the five biggest hazards, which are 261, 181, 145, 136, and 45, respectively. These hazards can easily trigger other hazards, which are important causes of seepage risk transmission. 65 (dam deformation), 66 (dam crack), 191 (drainage structure fracture), 157 (filter water failure), and 234 (blockage or siltation) are the five biggest hazards of in-degree value, which have degree values 58, 56, 53, 45, and 33 respectively. Because these are easily caused by other hazards, these hazards should be monitored and paid attention to in the prevention of seepage accidents.The cumulative degree distribution of the PNSRTP is shown in Figure5. The cumulative degree distribution presents a power-law distribution that has the approximate fit Pk=3.8428x−1.192 (R2=0.9468) [23]. The above result deviates from the power-law nature for lager k, which indicates that the PNSRTP has scale-free property [23]. The scale-free property shows that a few nodes have high degree values in the PNSRTP, which is consistent with the distribution of degree values in Figure 4. These nodes make the PNSRTP robust to random attacks. This is reflected in the fact that although the world’s major economies have invested a lot of resources in the safety management of the seepage system of tailings pond in the past, the seepage accidents of tailings pond often occur due to the inability to find out the key hazards (determine the importance of the hazards). At the same time, these high degree value nodes show vulnerability to specific attacks. If we can apply this characteristic to the treatment of seepage risk of tailings pond, determine the optimal treatment sequence of hazards, and block the correlation between hazards, the occurrence of seepage accidents will be greatly reduced.Figure 5
Cumulative degree distribution of the PNSRTP.


### 4.2.2. Average Path Length and Network Diameter

According to Pajek calculation, the diameter of the PNSRT network is 13, which represents the longest distance between two hazard nodes in the network. The distance between node 9 (mudslide) and 224 (low tailings water recovery rate) or node 8 (beyond standard earthquake) and 207 (flood drainage structures are directly located on the tailings sediment beach) is 13. They are the node pairs with the farthest risk propagation distance in the network.The average path length of the PNSRTP is 4.90, which means that the seepage risk propagates from one hazard node to other hazard nodes in the network with an average of no more than 5 nodes. The PNSRTP has more than 300 hazard nodes and nearly 2000 hazard relationships, but the average distance between the two hazard nodes is very short. The above characteristics show that the cause of seepage risk is complex and the propagation speed is fast. When the seepage risk is formed, if effective measures are not taken to control and manage it in time, the seepage accident of tailings pond may be caused.


### 4.2.3. Clustering Coefficient and Small-World Property

According to the definition of clustering coefficient, the node with degree value of 1 has no agglomeration. Therefore, when calculating the clustering coefficient of each node in the PNSRTP, the node with degree value of 1 is excluded. The clustering coefficient of each point in the PNSRTP is shown in Figure6. It can be seen from Figure 6 that the clustering coefficient of nodes is between 0 and 0.5. The clustering efficiency of hazards 83 (the rising speed of tailings between dam downstream and upstream is unbalanced) and 266 (insufficient production capacity of dryer) is 0.5. The clustering of other most nodes is between 0.05 and 0.35, and the distribution is more uniform. This reflects the aggregation of the PNSRTP around hazards 83 and 266.Figure 6
Clustering coefficient of nodes in PNSRTP.In order to determine whether the PNSRTP has the small-world property, this paper uses Pajek complex network software to generate a random network with the same number of nodes and average degree value as the PNSRTP, as shown in Figure7. After calculation, the average clustering coefficient of this random network is 0.04, which is far less than that of the PNSRTP (0.19). Combined with the fact that the average path length of the PNSRTP is less than 5, it can be concluded that the PNSRTP has the small-world property [32].Figure 7
Equal-sized seepage risk random network.


## 4.2.1. Degree Values and Degree Distribution

The degree values of each node in the PNSRTP are shown in Figure4. The degree value of the seepage hazard node is an important index to reflect the influence of hazards. According to the different directions of the relationship between hazards, it can be divided into out degree and in degree. Through the calculation using Pajek software, the average degree of the PNSRTP is found to be 12.22 and the network density is 0.02. It shows that a node with potential seepage hazard is directly related to 12.22 hazards on average, but the overall density of the PNSRTP is not large.Figure 4
Node degree in the PNSRTP.As can be seen from Figure4, the node with the largest degree is 340 (insufficient safety supervision), which can directly affect 261 kinds of hazards. 355 (lack of qualification and experience of personnel and institutions) belongs to the personnel system, which is the second largest hazard (182). The degree values of 345 (defects of safety production rules and regulations and operation procedures) and 344 (outdated specifications and standards for survey, design, construction, and acceptance) are 145 and 136, respectively. The degree values of 65 (dam deformation), 66 (dam crack), and 191 (drainage structure fracture) are all 59, of which 65 and 66 belong to the dam system and 191 belongs to the drainage system. 157 (filter water failure) also belongs to the dam system, for which the degree value is 49. The degree value of 339 (insufficient capital input) is 45, which belongs to the management system with hazards 340, 344, and 345, which highlights that the management factor plays a vital role in the safety management of the tailings seepage system. The degree value of 234 (blockage or siltation) is 41, which is the smallest hazard in the top ten hazards and also the only hazard belonging to the conveying system. It shows that the conveying system also has a certain impact on the seepage of tailings pond.From the perspective of out degree, 340 (lack of safety supervision), 355 (lack of qualification and experience of personnel and institutions), 345 (defects in safety production rules and regulations and operating procedures), 344 (outdated specifications and standards for survey, design, construction, and acceptance), and 339 (insufficient capital investment) are the five biggest hazards, which are 261, 181, 145, 136, and 45, respectively. These hazards can easily trigger other hazards, which are important causes of seepage risk transmission. 65 (dam deformation), 66 (dam crack), 191 (drainage structure fracture), 157 (filter water failure), and 234 (blockage or siltation) are the five biggest hazards of in-degree value, which have degree values 58, 56, 53, 45, and 33 respectively. Because these are easily caused by other hazards, these hazards should be monitored and paid attention to in the prevention of seepage accidents.The cumulative degree distribution of the PNSRTP is shown in Figure5. The cumulative degree distribution presents a power-law distribution that has the approximate fit Pk=3.8428x−1.192 (R2=0.9468) [23]. The above result deviates from the power-law nature for lager k, which indicates that the PNSRTP has scale-free property [23]. The scale-free property shows that a few nodes have high degree values in the PNSRTP, which is consistent with the distribution of degree values in Figure 4. These nodes make the PNSRTP robust to random attacks. This is reflected in the fact that although the world’s major economies have invested a lot of resources in the safety management of the seepage system of tailings pond in the past, the seepage accidents of tailings pond often occur due to the inability to find out the key hazards (determine the importance of the hazards). At the same time, these high degree value nodes show vulnerability to specific attacks. If we can apply this characteristic to the treatment of seepage risk of tailings pond, determine the optimal treatment sequence of hazards, and block the correlation between hazards, the occurrence of seepage accidents will be greatly reduced.Figure 5
Cumulative degree distribution of the PNSRTP.


## 4.2.2. Average Path Length and Network Diameter

According to Pajek calculation, the diameter of the PNSRT network is 13, which represents the longest distance between two hazard nodes in the network. The distance between node 9 (mudslide) and 224 (low tailings water recovery rate) or node 8 (beyond standard earthquake) and 207 (flood drainage structures are directly located on the tailings sediment beach) is 13. They are the node pairs with the farthest risk propagation distance in the network.The average path length of the PNSRTP is 4.90, which means that the seepage risk propagates from one hazard node to other hazard nodes in the network with an average of no more than 5 nodes. The PNSRTP has more than 300 hazard nodes and nearly 2000 hazard relationships, but the average distance between the two hazard nodes is very short. The above characteristics show that the cause of seepage risk is complex and the propagation speed is fast. When the seepage risk is formed, if effective measures are not taken to control and manage it in time, the seepage accident of tailings pond may be caused.


## 4.2.3. Clustering Coefficient and Small-World Property

According to the definition of clustering coefficient, the node with degree value of 1 has no agglomeration. Therefore, when calculating the clustering coefficient of each node in the PNSRTP, the node with degree value of 1 is excluded. The clustering coefficient of each point in the PNSRTP is shown in Figure6. It can be seen from Figure 6 that the clustering coefficient of nodes is between 0 and 0.5. The clustering efficiency of hazards 83 (the rising speed of tailings between dam downstream and upstream is unbalanced) and 266 (insufficient production capacity of dryer) is 0.5. The clustering of other most nodes is between 0.05 and 0.35, and the distribution is more uniform. This reflects the aggregation of the PNSRTP around hazards 83 and 266.Figure 6
Clustering coefficient of nodes in PNSRTP.In order to determine whether the PNSRTP has the small-world property, this paper uses Pajek complex network software to generate a random network with the same number of nodes and average degree value as the PNSRTP, as shown in Figure7. After calculation, the average clustering coefficient of this random network is 0.04, which is far less than that of the PNSRTP (0.19). Combined with the fact that the average path length of the PNSRTP is less than 5, it can be concluded that the PNSRTP has the small-world property [32].Figure 7
Equal-sized seepage risk random network.


## 5. Importance and Treatment Sequence of Hazard Nodes

The global network efficiency of seepage network refers to the average value of the reciprocal sum of the shortest path lengths between pairs of hazard nodes, which reflects the propagation speed of seepage risk in the PNSRTP [33,34]. According to the above definition, this paper takes the global network efficiency as an index to measure the management effect of seepage risk after the treatment of seepage hazard.The betweenness centrality and the degree value and the node clustering coefficient mentioned above are the indicators to measure the importance of nodes. In the process of seepage risk propagation, the node with larger betweenness centrality is the main channel of risk propagation. Therefore, in the treatment of tailings dam seepage risk, we should focus on the nodes with larger betweenness centrality. After calculation, the overall betweenness centralization of the PNSRTP is 0.0643 and the betweenness centrality of each node is shown in Figure8. It can be seen from Figure 8 that the distribution of the betweenness centrality of the nodes presents serious heterogeneity and the betweenness centrality among the nodes has serious uneven distribution. The betweenness centrality of hazards 65 (dam deformation), 267 (pipes and grooves deformation), and 253 (concentration equipment failure) is 0.0669, 0.0647, and 0.0577, respectively, which are significantly larger than those of other nodes, indicating that timely treatment of these hazards is helpful to reduce the spread of seepage risk of tailings dam.Figure 8
Betweenness centrality of nodes in the PNSRTP.In order to verify which one of the three indicators can reduce the global efficiency of the network more quickly and effectively, that is, to reduce the spread of seepage risk, according to the order (size) of the index value, the hazard nodes are treated (deleted) in turn in this paper and then the global efficiency of the network after treatment is calculated. In the management of hazard nodes, the hazard node with the largest index value is treated for the first time and then 5 hazards are treated at a time according to the order of index values, until all hazards are treated. The decline of the network efficiency of the PNSRTP under the three hazard remediation methods is shown in Figure9.Figure 9
The change of the network efficiency of the PNSRTP.As can be seen from Figure9, after the hazard of high clustering coefficient is treated, the network efficiency cannot decline rapidly. Even when the node deletion ratio is less than about 70%, the network efficiency shows an increasing trend. Therefore, the nodes with a large clustering coefficient are not suitable for priority governance. Both betweenness centrality and degree centrality can quickly reduce the network efficiency of the PNSRTP, but obviously, the effect of degree centrality is better. When the ratio of hazard treatment is less than 5%, the two indexes have the same effect on the reduction of seepage risk and even the betweenness centrality is slightly dominant. However, with the increase in remediation proportion, the gap between the two began to increase. When the governance ratio reaches about 30%, the network efficiency of the PNSRTP is quickly reduced to around 0 under the degree centrality, while the network efficiency is maintained between 0.1 and 0.15 under the betweenness centrality. Therefore, in the prevention and control of tailings pond seepage risk, we should select degree centrality as the index to measure the importance of nodes and give priority to the nodes with large degree value.


## 6. Discussion

The cause of seepage accident in tailings pond is complex, and the seepage hazards changes with the life cycle of tailings ponds, which makes it very difficult to identify the seepage hazard completely and accurately. At the same time, the existing methods of hazard identification are mainly based on the subjective judgment of researchers and these methods lack objective supporting evidence. In order to solve these problems, this paper divides the seepage system of tailings pond into eight subsystems according to its functions and composition characteristics and identifies the seepage hazards in different life cycles according to laws and regulations, accident cases, and other evidence. The evidence is collectively compiled by the most experienced and knowledgeable experts in the industry. At the completion of the compilation, it has undergone decades of practical application verification. After multiple rounds of updates and improvements, the evidence can fully meet the goal of identifying all the hazards of the seepage system [29]. In a sense, the EIMTSH is a separation of the causal model, which divides the complex system and various influencing factors into small modules to reduce the difficulty of hazard identification.The nodes and edges of the complex network can better represent the operation process of the complex system. Therefore, this paper takes the seepage hazards as the nodes and the relationship between hazards as the edges to represent the propagation process of seepage risk of tailings pond and constructs the PNSRTP. By analyzing the network characteristics of the PNSRTP with universal applicability, we can get the following: (a) The cumulative degree distribution of the PNSRTP presents a power-law distribution, which shows that the PNSRTP presents the scale-free property. (b) The PNSRTP has a larger clustering coefficient and smaller characteristic path length, which indicates that the network is a small-world network. Compared with the nodes with high betweenness centrality and high clustering coefficient, the nodes with higher degree value can reduce the network efficiency more quickly, which indicates that the nodes with higher degree value have greater importance in the propagation of seepage risk and belong to the hazard nodes with priority governance. It should be noted that the conclusion here is drawn from the perspective of the PNSRTP as a whole. Since the hazards of the tailings ponds and the relationship between hazards are constantly changing in a real tailings pond, it is necessary to use the safety inspection data, work logs, and safety evaluations of the tailings ponds to determine them.The advantage of the EIMTSH is that it provides support for the complete identification of hazards and the relationship between hazards. However, these support evidence pieces are simplified to have the same reliability without considering the strength of the relationship between hazards, which is obviously different from the actual propagation process of seepage risk. In addition, we analyzed the PNSRTP as a universal network, which contains all the hazards and their relationship of different types and different life cycles of tailings ponds, but the actual operating tailings pond only has some of these hazards and their relationship. This may lead to that some properties and conclusions obtained by analyzing the universal PNSRTP are not applicable to the actual seepage system of tailings ponds.In order to solve the above problems, the authors will consider the classification of supporting evidence in the future and divide the relationship weight between hazards by combining with AHP, triangular fuzzy, and other methods. At the same time, a number of specific cases are selected to use the above methods for application analysis and research, the nature differences between the PNSRTP and the case networks are observed, and then the above methods are modified and improved, so as to build a more practical research system for the seepage risk of tailings ponds.


## 7. Conclusion

This paper uses the proposed EIMTSH to identify the hazards of the tailings pond seepage system and obtains a hazard list supported by evidence. This list includes a total of 313 hazards and 1912 relationships among hazards. This list will help decision makers and scientists to actively participate in the evidence-based risk assessment process for tailing pond seepage.Based on the identified list of seepage hazards in tailings ponds, the PNSRTP with nodes of three layers and two stages is constructed based on the complex network theory, which realizes the characterization of the seepage risk propagation process of tailings pond. Through the analysis of the characteristics of the PNSRTP, we can find that the PNSRTP has the scale-free property and small-world property.In this paper, the network efficiency is selected as the criterion of seepage risk propagation ability. By comparing the effects of degree centrality, node betweenness centrality, and clustering coefficient in reducing the network efficiency of the PNSRTP, it is concluded that nodes with higher degree values play a more important role in the process of seepage risk propagation. Through giving priority to the treatment of nodes with a high degree value, the seepage risk can be reduced more quickly and the occurrence of seepage accidents can be avoided, which is conducive to the sustainable development of the mining industry.



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*Source: 8704259-2021-11-08.xml*