Water-conducting Fractured Zone Research Articles

Study on Height Development Characteristics of Water-Conducting Fracture Zone in Fully Mechanized Mining of Shallow Thick Coal Seam under Water

The height of water-conducting fracture zone (HWCFZ) is one of the important technical parameters for water-preserved coal mining. The purpose of this paper is to acquire information about the height development characteristics of water-conducting fracture zone (WCFZ) in fully mechanized mining of shallow thick coal seam under water body in western mining area of China. The 91,105 fully mechanized mining face of Daheng coal mine under composite water body was taken as the research object, the development height, morphological characteristics, development and evolution process of WCFZ in working face mining were studied through underground up-hole water injection method by intervals, borehole TV and numerical simulation. The results show that the HWCFZ in 91,105 fully mechanized mining face is 52.7~53.6 m, and the fracture mining ratio is 12.55~12.76. The final development form is saddle-shaped with “large at both ends and small in the middle”. It is accurate and reliable to determine the development characteristics of overburden fractures and the HWCFZ by the field measurement of the combination of underground upward hole segmented water injection method and borehole TV. The development height of the water-conducting fracture zone obtained by numerical simulation is consistent with the field measured results. The development and evolution of the height of WCFZ presents four stages: “development–slow increase–sudden increase–stability”. When the WCFZ develops to a certain layer, the cracks generated by the weak strata in the fracture zone of overlying strata on the working face will automatically close with the advancement of the working face, resulting in “bridging phenomenon”, which inhibits the further development of the WCFZ. That is, the existence of soft rock with a certain thickness in overburden will become the key inhibiting layer for the development of WCFZ, effectively blocking the communication between water-conducting fracture and overlying aquifer. The research results are intended to provide guidance for the implementation of water preserving mining and ecological environment protection in ecologically fragile areas in western China.

Characteristic Developments of the Water-Conducting Fracture Zones in Weakly Cemented Overlying Strata of Jurassic Coal Mines in Western China

The overlying weakly cemented, and poorly performing strata in Jurassic mines of western China have mechanical properties that are generally lower than those in the Carboniferous-Permian coal mines of central and east China. During coal mining, the overlying strata easily deform and fracture. These then formed water-conducting channels, triggering a series of eco-environmental issues, including ground fracturing, collapsed surfaces, declined underground water levels, deserted lands, and even severe water/sand burst accidents. To study the fracture characteristics of weakly cemented overlying strata and the evolution law of water-conducting fractures in Jurassic coal mines in western China, this study selected Tashidian Erjingtian Mine in Korla, Xinjiang, as the research object. Based on the simulation data obtained with physical analog model testing and field monitoring results, the authors investigated the development of water-conducting fractures in the weakly cemented overlying strata during the coal seam mining process. We simultaneously determined the location of key strata in the working face based on key stratum theory. According to the present research results, key strata controlled the development height of water-conducting fractures. When the primary key stratum or sub-key stratum was not fractured, the development of water-conducting fractures was stagnant; water-conducting fractures developed abruptly when the primary key stratum or sub-key stratum was cracked. The heights of water-conducting fractures in the weakly cemented overlying strata of western China exceeded that of similar stopes of central and east China. These research results provided theoretical and technical support for safety in production at Tashidian Coal Mine. In addition, they offered a reference for green and safe production in Jurassic coal mines of western China.

Reasonable Working-Face Size Based on Full Mining of Overburden Failure

To improve production efficiency and prevent potential disasters in coal mines, comprehensive research methods such as similar simulation, numerical simulation, theoretical analysis, and on-site detection were used in this study. The migration characteristics of overburden rock under different working face lengths and development heights of water-conducting fracture zones were investigated via these methods in order to determine the reasonable length of the working face. The results show that the regularity of the development height of water-conducting fracture zones in similar simulations and numerical simulations is highly consistent, and the final stable values are 48 and 50 m. When the working face length was 300 m, the error between the simulated value and the value calculated from the formula dropped below 10% and exhibited a further decreasing trend; as a result, the working face length of 300 m was found to be the turning point for the development height of the water-conducting fracture zone to become stable. Based on the simulation results and mining damage theory, the critical size of the working face was 307.6 m, and the height of the water-conducting fracture zone was determined to be in the range of 45.5–60.5 m. The actual detection result of the height of the water-conducting fracture zone under the critical size of the working face was 55 m, which conforms to the law obtained from the simulation. Finally, the reasonable working face length under the geological conditions of a coal mine was determined to be 300–400 m. This study offers important reference value for determining the reasonable working face length under similar geological conditions, and may have significance for the sustainable development of coal resource mining.

Research on Water-Conducting Fractured Zone Height under the Condition of Large Mining Height in Yushen Mining Area, China

Abstract Accurately predicting the development height of the water-conducting fracture zone (HW) is imperative for safe mining in coal mines, in addition to the protection of water resources and the environment. At present, there are relatively few fine-scale zoning studies that specifically focus on predicting the HW under high-intensity mining conditions in western China. In view of this, this paper takes the Yushen mining area as an example, studies the relationship between the water-conducting fissure zone and coal seam mining height, coal seam mining depth, hard rock scale factor, and working face slope length, finally proposing a method to determine the development height of the HW based on multiple nonlinear regression models optimized using the entropy weight method (EWM-MNR). To compare the reliability of this model, random forest regression (RFR) and support vector machine regression (SVR) models were constructed for prediction. The findings of this study showed that the results of the EWM-MNR model were in better agreement with the measured values. Finally, the model was used to accurately predict the development height of the hydraulic conductivity fracture zone in the 112201 working face of the Xiaobaodang coal mine. The research results provide a theoretical reference for water damage control and mine ecological protection in the Yushen mine and other similar high-intensity mining areas.

Hydrochemical and isotopic comparison of crystalline bedrock aquifers in two geological disposal research sites in South Korea using samples collected during and after borehole drilling

Hydrochemical and isotopic characteristics of crystalline bedrock aquifers were investigated down to 500 m below ground level at two geological disposal research sites. Groundwater samples were collected every 50 m during drilling including water from several fracture zones (n = 24) and at water-conducting fracture zones after the drilling was completed (n = 27) to understand the impact of sampling times, i.e., during versus after drilling, on the characterization result. Both aquifers were highly weathered and showed transport in fractured rocks, which made it difficult to determine the effect of sampling times. Despite the similar ranges of hydraulic conductivities, the BH (gneiss) groundwater showed higher total dissolved solids including Na, F, and HCO3 and carbon-13 isotopes of dissolved inorganic carbon, older carbon-14 ages, but lower dissolved oxygen, oxygen and hydrogen isotopes of water, and sulfur isotopes of sulfate than the AH (granite) groundwater, indicating the extensive water rock interaction through long pathways in BH. Sulfate reduction was also observed in deep anoxic environment in BH, whereas the AH groundwater seemed to be affected by recent recharge through permeable fractures regardless of depth. Redox potential (Eh) increased in samples collected after drilling, in particular in AH, and Fe and negative Eh were not detected in groundwater collected after drilling in both areas, which implied oxidization after drilling in particular in aquifers with recent recharge. The study result suggests isotopic investigations combined with hydrochemical characterization to assess anoxic conditions for geological disposal, if possible, during drilling before grouting to accurately assess the redox condition in crystalline bedrock aquifers.

Evaluation of Water Inrush Hazard in Coal Seam Roof Based on the AHP-CRITIC Composite Weighted Method

The more complex the hydrogeological conditions of a mine, the more likely the coal seam is to experience water inrush during the mining process, and the greater the degree of the water inrush hazard. The scientific and reasonable prediction of water inrush in mines with complex hydrogeological conditions is of great significance to the safe and efficient operation of coal mines. Taking the roof water inrush problem of the No. 3 lower coal seam in the Jisan Coal Mine as the research object, the factors affecting the roof water inrush of the coal seam were comprehensively considered from three aspects: the aquifer property, the mining fracture development and the geological structure. The evaluation index system was constructed by selecting 10 factors, including the aquifer depth and thickness, core recovery rate, brittle–plastic rock thickness ratio, number of water-resisting layers, development height of the water-conducting fracture zone, fault density, frequency density, scale index and variation coefficient of the coal seam floor dip angle. At the same time, based on the dual influence of subjective and objective weighting, the scientific and reasonable weight of each factor was ensured. The AHP-CRITIC composite weighting method was used to calculate the comprehensive weight of each factor. Finally, the roof water inrush risk prediction model was constructed. According to the prediction results, the study area was divided into a low-risk area, medium-risk area and high-risk area. Compared with the actual situation, the prediction results were basically consistent with the actual situation, and the prediction results can provide the basis for the prevention and control of water in a coal mine.

Overburden Failure Associated with Slicing Mining in a Super Thick Coal Seam under Special Weak Aquifers

With the increasing improvement of national ecological standards, the eco-environmental problems caused by super thick coal seam mining in western China are becoming more and more serious. The failure law of weak overburden stratum is an important factor affecting the safe mining of coal. The failure characteristics of weakly cemented overburden under high-intensity mining in the mining area of western China were studied. For this purpose, a case study was conducted in the 1101 working face of the Baituyao Coal Mine in Ürümqi County. Based on the analysis of geological conditions in the study area, we combined empirical calculations with engineering analogy, physical simulation, and numerical simulation to comprehensively analyze the characteristics of mining-induced overburden failure. The study showed that the overburden in the study area had several unfavorable engineering geological characteristics, including ease of softening in the presence of water. The Middle Jurassic Xishanyao Formation is a directly recharged aquifer with a weak water-retaining property. Overburden failure mainly occurred at the two ends of the open-off cut. During the mining process, vertical fissures and bed-separated fissures were periodically developed and closed, and the fissures were interconnected. The overburden was fractured, and the fractured zone showed a trapezoidal shape, tapering off from bottom to top. The heights of the caving zone and the water-conducting fracture zone were 25 and 280 m, respectively, in the 1101 working face of the Baituyao Coal Mine, and the ratio of fracturing to mining height was 14.0. Due to the weakly cemented overburden and the presence of the Neogene weak aquifer, the risk of water and sand bursts still exists in this working face under high-intensity mining. Our findings shed light on the safe mining and environmental protection of the ground surface in coal mine shafts in western China.

Evaluation on Development Height of Water-Conduted Fractures on Overburden Roof Based on Nonlinear Algorithm

Based on the support vector machine theory, the particle swarm algorithm is used to optimize parameters, combined with an analytic network process in order to feature dimensionality reduction of the original data, and a nonlinear algorithm model combining statistical analysis and machine learning analysis is established. Taking the relevant data of overlying rock from two zones in Yingpanhao Coal Mine as an example, the main factors such as rock tectonic development, coal seam dip, mining height, mining operation method and stope width are ranked according to the weights of their contribution to the development height of the two zones in order to determine the main control factors, such as stope width and mining height. Using MATLAB as the experimental platform, 16 sets of two-dimensional mine data similar to the geology of the study area were divided into training and test sets for prediction and simulation, comparing the optimal solutions of various optimization-seeking algorithms to obtain quantitative prediction results based on the nonlinear algorithm model. The kriging interpolation process was carried out by ArcGIS to realize qualitative visualization, and effective classification is carried out according to the natural breakpoint method to obtain six development height divisions of the water-conducting fracture zone in the study area. The results show that the prediction model of the development height of two zones in the coal roof based on the non-linear algorithm has better accuracy and generalization ability. Predicted by the test set, the model’s prediction result MAE is less than 10%, and the accuracy is better than the traditional empirical formula method, which makes up for its lack of rough calculation accuracy and solves the problem of not being able to locate the height of roof crack development at specific borehole locations, which has significance in guiding the prediction and prevention of roof water damage and subsidence disasters.

Determination of the Height of Overburden Water-Conducting Fracture Zone in 215102 Working Face of Yue Nan Coal Mine

In order to extract gas accurately in Yue Nan coal mine and prevent gas over limit and gas accidents, a combination of theoretical analysis and numerical simulation was used to investigate the height of the overburden caving zone and fracture zone in the working face, using 215102 working face as the engineering background. The results show three key strata in the 215102 working face, namely siltstone, sandy mudstone, and sandy mudstone. The empirical formula’s calculation results are in good accord with the findings of the theoretical analysis, which indicates that the height of the water-conducting fracture zone created by mining in 215102’s working face is 87.35 m. The plastic zone, stress distribution and displacement variation of the model overburden of the working face were analyzed separately in the numerical simulation. The results of the plastic zone simulation show that the caving zone’s maximum height is about 15.96 m, and the fracture zone’s maximum height is approximately 82.39 m. The stress distribution shows that the caving zone’s greatest height is around 13.65 m, while the fracture zone’s maximum height is roughly 77.24 m. The amount of overburden subsidence proves that the caving zone’s maximum height of about 10.08 m, and the fracture zone’s maximum height of approximately 82.69 m. The height of the overburden caving zone and fracture zone of 215102 working face are ultimately found to be 14.02 m and 76.42 m, respectively, based on theoretical analysis, empirical formula calculation, and numerical simulation findings.

Research on the Development Law of Water-Conducting Fracture Zone in the Combined Mining of Jurassic and Carboniferous Coal Seams

The accurate prediction of the height of the water-conducting fracture zone is essential for the prevention of roof damage by water disasters in coal mines. The development law of water-conducting fracture zone in combined mining of Jurassic and Carboniferous coal seams is different from that of previous research results. This study constructed an engineering geomechanics model to carry out material simulation and numerical simulation. The changes of stress, displacement, and fracture propagation were analyzed and compared with the results of formula calculation and field measurement, revealing the combined action of Jurassic and Carboniferous coal seams on the development law of water-conducting fracture zone. The results show that: (1) stress concentration is formed in the middle of the goaf in Jurassic coal seam, resulting in the high height of water-conducting fracture zone and the fracture “closed”; (2) the mining of Carboniferous coal seams caused the second subsidence of Jurassic goaf, and closed fracture “activated”; (3) the height of the water-conducting fracture zone obtained by the empirical formula is small, which is quite different from the actual situation. These research results are of significance for determining the height of the water-conducting fracture zone in Jurassic and Carboniferous coal seams during combined mining and the prevention of coal roof water hazards.

Research on the Height of the Water-Conducting Fracture Zone in Fully Mechanized Top Coal Caving Face under Combined-Strata Structure

In order to study the development height of the water-conducting fracture zone in a fully mechanized top coal caving face. The E2311 working face of Gaohe Coal Mine was chosen as the research object, and the combined-strata structure and the rock layer synergistic movement mechanism were determined by combining engineering geological investigation and theoretical analysis. The height of the water-conducting fracture zone at the working face was calculated based on the combined-strata structure, and then the theoretical results were verified by numerical simulation and field measurement. The results show that after the coal seam is extracted from the working face, the movement of the overlying rock layers is in the form of bending and sinking movement of the rock layer group as a unit. Each rock layer group is controlled by a supportive lower layer with greater thickness and strength, driving the upper layers of weaker rock layers to synchronize and coordinate the movement; the sinking curvature is the same, after the lowermost support layer is bent and broken, its overlying weaker rock layers will move and break at the same time. The height of the water-conducting fracture zone of the working face were obtained by theoretical calculation, numerical simulation, and field measurements, which are 83.82 m, 84.3 m, and 86.6 m, respectively. The results are nearly consistent, thus the prediction of the height of the water-conducting fracture zone under the combined-strata structure is more accurate.

Adaptive filtering of microseismic data for monitoring a water-conducting fractured zone in a mine

Water-conducting fractured zones in a rock mass can cause problems in mining. Attempts have been made to monitor their development using microseismic signals. However, due to the lack of prior information, it is difficult to filter out mixed low-frequency interference with traditional denoising methods. In this work, the proposed adaptive filtering algorithm is applied after the wavelet packets are decomposed. It is based on a cross-correlation analysis. The algorithm takes a high-quality signal in the common source waveform as prior information and applies the corresponding correlation coefficients between subbands as a threshold. The algorithm was verified with simulations. The results show that low-frequency interference can be effectively suppressed by filtering. For single-frequency interference, the signal-to-noise ratio increased from − 10.18 to 13.97, and the root-mean-square error was 43.88. For multi-frequency interference, it increased from − 10.01 and − 2.63 to 13.50 and 7.99. The root-mean-square errors were 46.31 and 138.07. The narrower the main frequency band of the interference signal and the less the overlap of the main frequency band of the interference signal and the effective signal, the better the filtering effect. When the algorithm was applied to microseismic data collected in the field, the number of effective channels increased and the accuracy improved. The development of a water-conducting fractured zone in the field was consistent with the microseismic location obtained after interference was removed by the algorithm, which indicates that it is feasible to monitor a water-conducting fractured zone by analyzing microseismic waveforms with the adaptive filtering algorithm.

Study of the Evolution of Water-Conducting Fracture Zones in Overlying Rock of a Fully Mechanized Caving Face in Gently Inclined Extra-Thick Coal Seams

To study the caving of thick hard overburdens and evolution of water-conducting fracture zones in fully mechanized top-coal caving faces of gently inclined extra-thick coal seams, we comprehensively analyzed the 8103 working face of the Beixinyao Coal Mine. We investigated to the caving characteristics of thick hard overburden in fully mechanized top-coal caving faces, fracture information of the internal structure of overburden, and development heights of the “two zones” of overburden after coal mining. Our research methods included those of similarity simulation experiments, such as the use of microseismic monitoring systems, numerical simulations, theoretical analysis, and engineering practice. The results showed that the overlying strata generally experienced stages of roof caving, crack formation, delamination, crack development, and surface subsidence. Due to the influence of overlying strata movement and mining, the separation layer experienced an evolution process called “emergence-development-closure”, where the height of the overlying strata caving envelope increases with the advancing of the working face. When full mining was achieved, the overlying strata caving height was stable, and the height development range of the water-conducting fracture zone was 100–120 m, which is consistent with the height of the overlying strata caving envelope. Most microseismic events occurred near the water-conducting fracture zone, and the water-conducting fracture zone was formed in an area with concentrated energy density. In our numerical simulation, the concentrated distribution area of the fracture field was characterized by a “bridge arch”. The fracture development model in the middle of the goaf was higher than at both ends of the working face, and roof strata deformation was obvious. When the energy value of microseismic event reaches 108.708 J, cracks are produced, and these cracks gradually penetrate to form water-conducting fracture zones. Engineering practice showed that the height range of the water-conducting fracture zone was 98–123 m, and caving of the thick hard overburden and evolution of the water-conducting fracture zone in a fully mechanized top-coal caving face provide a scientific basis for water prevention and control.

A novel collaborative study of abnormal roof water inrush in coal seam mining based on strata separation and wing crack initiation

Separation water inrush poses a potential threat to safe mining on the working face, whose mechanism should be investigated in order to take better prevention and control measures. In this study, aiming at the problem of separation water inrush under hydrostatic pressure, the 21805 working face of the Yushujing coal mine was chosen as the research object to establish an in-house similar simulation experiment. The experiment could reveal the evolution law of bed separation space, the process of water accumulation in bed separation space, and the breaking characteristics of separation water inrush. Meanwhile, in order to theoretically interpret the evolution of water-conducting fractured zone (WCFZ), an analytical model for wing crack initiation from compression-shear fracture and tension-shear fracture that considers T-stress was derived. The analytical model comprehensively considers the effects of overlying strata load and aquifer water pressure, fracture geometry, and rock properties. The results show that the time of separation water inrush obtained by the similar simulation experiment is consistent with the field result, and the orientation of new cracks generated due to water injection also coincides with the analytical solution. In addition, it is found that the development of bed separation space is a long-term process, which can provide a theoretical basis for the prevention and control of separation water inrush.

Quantitative evaluation and planning method of shallow surface water response in multi-face mining—Case study regarding Zhuanlongwan coal mine

Multi-area coal extraction can cause aquifer depressurisation and subsurface dewatering, in which the mechanism of overburden permeability and shallow water responding to underground gob keeping extending is the key. This paper focuses on the water resource protection in ecologically fragile mines in western China. With the equivalent permeability coefficient(EPC) and subsurface hydraulic responses as basis, the paper conducted mathematical statistics and theoretical analysis to construct a decision-making model for multi-panel longwalls and a longwall design methodology that considered subsurface water stability. Firstly, fitting the field measurement data produced an empirical equation regarding the height of water-conducting fracture zone (HWCFZ), and a model for quantifying the correlation between the damage values of effective soil units and effective bed rock units was established, by which the EPC was quantified. Secondly, the paper developed a subsurface water quantification model that considered infiltration recharge to study the subsurface piezometric evolution with varying geometry, range, and number of longwall units, further revealing the subsurface water responses to varying mining zones. Finally, a model for evaluating the subsurface water depressurisation was proposed and applied to study the subsurface water responses to multi panels in Zhuanlongwan Coal Mine. The longwall design obtained via the decision-making model agreed with the piezometric variation in the mine, suggesting that this research can provide theoretical and technical supports for green mining.

Comprehensive Water Inrush Risk Assessment Method for Coal Seam Roof

In order to prevent coal mine water inrush accidents, it is necessary to appropriately assess the water abundance of coal mines based on drilling and geophysical data. This paper studied a comprehensive risk assessment method of water inrush. First, a water inrush risk index was proposed based on the analytic hierarchy process-entropy method (AHP-EM) and the water-rich structure index was proposed based on the geological data coupled calculation, then weighted two indices above which established the comprehensive water inrush risk assessment method. Secondly, eight factors were chosen as risk control factors of water inrush: core recovery, aquifer thickness, distance from the indirect aquifer to the coal seam, aquiclude thickness, height of water-conducting fracture zone, sand-mud ratio, total layers of aquifer and aquiclude, and the equivalent thickness of sandstone. Finally, the No. 2 coal seam of Dahaize coal mine was taken as the research object, the factors were calculated, and a comprehensive water inrush assessment model was constructed. With site investigation and observation, the water inrush risk assessment model of the No.2 coal seam roof is consistent with the actual mining situation, which verifies the validity of the model. In addition, this method was used to evaluate the water-richness of the weathered bedrock fractured aquifer in the Zhangjiamao coal mine. The practical application of the two mines has verified the generality of the approach. The research could provide scientific assistance for mine water hazard mitigation and mining safety.

Calibration of Water Inrush Channel and Numerical Simulation of Water Inrush Process in Coal Mine Roof

The surrounding rock of a coal mine roof fractures with the excavation of the underground working face in coal mining. These mining-induced fractures are connected and extended upward to form water inrush channels. A water inrush accident may occur when there is a sufficiently large water source. To elucidate the formation mechanisms of the roof water inrush channel and the characteristics of water inrush in goafs, we performed a case study of No.18401 Panel of Xiqu Coal Mine in China and determined whether the roof water inrush channel is connected by theoretical calculation and microseismic monitoring. The modified mechanical parameters of rock masses were embedded into the numerical model based on microseismic data. Microseismic monitoring and numerical simulation were organically combined to analyze the connection process of the water inrush channel, after which the roof water inrush channel is calibrated on the No.18401 Panel. We established a non-Darcy flow model for water inrush in the water-conducting fractured zone of mines by coupling the Darcy, Forchheimer, and Navier–Stokes equations. Finite element language and its compiler (FELAC) was used to study the water inrush mechanism of non-Darcy seepage. The results show that the pressure, velocity, and porosity in the water-conducting fractured zone are non-uniform in water inrush occurrence and development, and the mixed fluid mainly passes through the “dominant channel.” The development of water inrush is accompanied by the release of the hydrostatic pressure in the aquifer, the sudden increase of the velocity at the water inrush position, and the increase in fluid concentration. Hence, the underground water inrush can be predicted and prevented by monitoring the aforementioned indicators. This research is of great significance for the calibration of the water inrush channel of the roof and the prediction of water inrush disasters.

Study on the damage characteristics of overburden of mining roof in deeply buried coal seam

The study of water-conducting fracture zone development height is key to the scientific prevention and control of water damage in mines. Based on the geological conditions of the Wenjiapo coal mine in Binchang, China, this paper investigates the development of water-conducting fracture zone in overlying bedrock during mining under large buried depth and huge thick aquifer by combining on-site well-location microseismic monitoring and laboratory similar material simulation. To overcome the limitation of the " limited outlook " of water-conducting fracture zone investigation, the spatial development characteristics of roof fissures in coal seam mining were determined by on-site " the underground - ground" combined microseismic monitoring and follow-up monitoring, and the development of overlying rock fracture under the large depth of burial was concluded. The fractures were mainly distributed in the upper part of the protective coal pillar on both sides of the working face, but less in the upper part of the working face, and primarily distributed in the protective coal pillar on the side of the working face and the adjacent mining area. To verify the accuracy of the conclusion, the overlying bedrock movement and deformation characteristics and the development process of the hydraulic fracture zone during coal seam mining were analyzed by simulating similar materials in the laboratory, using the monitored area as a prototype. The results show that the development height of the mining fracture zone obtained from microseismic monitoring is basically consistent with the simulation results of similar materials. The research finding have significant implications for the study of fracture distribution characteristics and the evolution law of mining overburden, and provide a foundation for scientific prevention and control of water damage on the roof.

Mechanism of formation of water-conducting fractured zones with deep mining in the Jiaojia gold mine, China

Mechanism of formation of water-conducting fractured zones with deep mining in the Jiaojia gold mine, China

Research on 3D Development Characteristics of Water-Conducting Fractured Zone Based on Field Measurement

With the large-scale mining of coal resources in western China, coal resources are gradually shifting from shallow to deep mining. In coal seam mining, the overlying rock water-conducting fractured zone (WCFZ) is the main factor causing mine water damage and water resource damage. Accurately grasping the development height of the water-conducting fissure zone is the key to the prevention of water hazards and the protection of water resources in medium–deep coal seams. In this study, the 3D development form of the WCFZ in the middle and deep coal seam mining is studied by the integrated method of drilling and 3D seismic survey, taking the first mining face of Xiaobodang No.1 mine in Yushen such that the height of the WCFZ measured by drilling is 81.50–177.07 m. The height of WCFZ development in the 3D seismic survey was 79.83–178.03 m, and the morphology of the WCFZ was saddle-shaped. This study provides methodological guidance for predicting the 3D morphology and developmental characteristics of the WCFZ. The results obtained are of great significance for the safe, green, and efficient mining of coal seams in medium and deep buried ecologically fragile environments.