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In order to explore the mechanical response characteristics of faults when the working face is normal fault mining, a numerical simulation model is established based on the engineering geological conditions of 1105 working face in Gaozhuang Coal Mine to obtain the evolution characteristics of fault damage variables under mining disturbance. The simulation results are analyzed by multiple linear regression analysis and the mechanical model of footwall rock mass is established to obtain the relationship between fault damage variables and coal stress. The results show that the fracture damage of the fault develops from the high rock layer to the low rock layer. When the fault damage variable reaches the critical value, the fault has the condition to activate; under the influence of working face mining, the development of fault damage variable is earlier than the increase of abutment pressure of coal body. Fault damage variable can be used as a key index to predict fault activation and coal body stress increase; through multiple linear regression analysis, the determined influencing factors of fault damage variables are distance from fault, vertical stress, internal friction angle of fault and fault cohesion; in the process of working face to fault mining, the decrease of coal width between working face and fault causes the increase of coal stress. At the same time, the mining leads to the damage development of the fault surface, the effective bearing area between the upper and lower rock mass is reduced, the weight of the rock mass is mostly borne by the lower coal body, and the coal body stress is further increased.

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The ore (rock) bodies between the 570 m and 630 m levels in Jiaojia Gold Mine are characterized by well-developed joints and fissures, prone to forming wedge-shaped unstable structures, leading to rock mass col- lapse. Geological drilling and structural surface condition surveys indicate that the rock mass in Jiaojia Gold Mine is relatively fractured, with well-developed joints and a wide range of joint occurrence distributions. This study investi- gates and summarizes the convergence deformation patterns of roadways under mining disturbances. Radar testing and analysis reveal that the damage depth of the roadways in Jiaojia Gold Mine generally remains at about 2 m, with many weak structural surfaces present, necessitating timely reinforcement measures. This research provides a rational plan for the support of the ore body and guides the reasonable selection of stope structural parameters to ensure safe production in this mining section. It offers valuable insights for managing fractured rock mass in similar mines. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Ordovician thermal reservoir in Liaocheng East Thermal Field is the preferred area for exploration and development of bedrock thermal reservoir in Shandong Province. In this paper, a regional deep-circulation fracture-karst bedrock thermal reservoir model of semi-structural trap is established by analyzing the geothermal characteristics of caprock, reservoir,water source, heat source and channel in the area. The analysis shows that the semi-trap deep circulation occurrence characteristics not only improve the hot water mineralization and trace elements, but also lead to the problems of strong reservoir sealing, large mining disturbance and difficult sustainable utilization.Based on the measured data of the observation wells in the area for many years, the empirical formula of mining depth reduction is established. The variation coefficient method and comprehensive index method are used to evaluate the disturbance of thermal reservoir mining in the area. It is considered that the exploitation of bedrock thermal reservoir in the area leads to the decrease of water level, water volume, reservoir pressure, temperature and service life. There are few secondary problems such as disturbance of water quality, land subsidence, thermal pollution, environmental pollution and cross-layer water source pollution. Combined with the regional reinjection test, the suitable local mining and reinjection schemes are discussed : centralized mining, gradient utilization, reinjection in the same layer, balanced mining and reinjection. The reinjection wells of bedrock thermal reservoirs in the area should be set in the range of 300-500 m around the mining well, and the tail water temperature should be 35-40 °C. This study provides a theoretical basis for the sustainable utilization of bedrock thermal reservoirs in the area. [ABSTRACT FROM AUTHOR]

The roof of the large cross-section roadway under the short goaf area is disturbed by coal seam mining and roadway boring twice, in order to study this two influences, taking the II 8224 open-off cut roadway in Renlou coal mine as the engineering background, the influence depth of goaf unloading and the disturbance characteristics of roadway mining were analyzed by theoretical analysis, numerical simulation and field measurement. The results show that the theoretical calculation results and numerical simulation results of unloading depth in goaf are consistent with the analysis results of drilling core, and the rock strata within the scope of unloading influence will rise up. The subsidence time of large section roadway roof under goaf is 14 d, and the maximum subsidence velocity is only 15 mm/ d. It is concluded that the influence depth of disturbance and failure of upper goaf unloading on floor rock is 5. 2 m. Under the influence of goaf unloading, the subsidence time, subsidence speed and subsidence amount of roadway roof are small. [ABSTRACT FROM AUTHOR]

Seepage stability is an important factor to ensure the safety of underground mining when mining ore bodies under rivers.To analyze the influence of the Toudaoyangcha river on the seepage stability of underground mining in Sansheng Iron Mine, based on the hydrogeological concept model, the seepage characteristics under the influence of underground mining disturbance in Sansheng Iron Mine were analyzed by using Flac3 D numerical analysis software.The results show that the stoping is less affected by the seepage of the river level, and there is no water inrush risk in the mine.The calculation results can provide a reference for safe mining in mines. [ABSTRACT FROM AUTHOR]

Taking the soil samples collected at Baorixile Open-pit Mine as the research object, based on the relevant soil hydraulics parameters measured in the laboratory, the groundwater level in the field survey and the relevant meteorological data, the soil water migration law was studied in the aeration zone from 1990 to 2016, the feasibility of using soil water flux to estimate precipitation infiltration coefficient is discussed, and the effects of groundwater level decline and soil reconstruction of dump on precipitation infiltration coefficient are analyzed. The results showed that under the condition of natural rainfall, the average soil water flux at 10 m in the steppe area was 20.38 mm, and the average precipitation infiltration coefficient for many years was 0.06; with the increase of groundwater depth, the precipitation infiltration coefficient firstly decreases and then keeps stable at 2 m, that is to say, the drop of groundwater level in the mining area has little effect on the recharge of groundwater by precipitation; at present, the soil reconstruction model of “humus + clay + medium sand” can greatly improve the moisture content of humus and play a positive role in the vegetation restoration of open-pit dump, but to a certain extent, it reduces the infiltration coefficient of precipitation, which makes it unfavorable for groundwater to accept the recharge of meteoric precipitation.

In order to grasp the evolution law of the mechanical characteristics of the floor under the disturbance of the first coal seam mining in Pingmei No.8 coal mine, this paper uses COMSOL Multiphysics software to simulate the stress distribution characteristics of the underlying coal rock layer under the disturbance of Ji15 coal seam mining. Results show that: under the disturbance of first mining layer, the vertical stress field of underlying coal stratum is symmetrically distributed in the middle of working face. Obvious stress-relief zone could be seen above and below the working face of first mining layer. There is stress concentration at both ends of the mining area, and the maximum stress concentration reaches 2.56. The stress-relief effect is within 30 m from the bottom of first mining layer. Meanwhile, the stress releasing rate could reach more than 95%, and the length of sufficient stress-relief zone could reach 70.22% of the length of working face in first mining layer. Therefore, the coal seam within 30 m of stress-relief layer should be preferentially selected as the first mining layer.

Taking 1604 working face of Guhanshan Mine as the research background, by means of a high-precision micro-seismic monitoring system and numerical simulation, the dynamic failure characteristics of the surrounding rock and the danger of water inrush from the floor during the mining of the working face are studied. The results show that the asymmetrical energy release phenomenon occurs along the empty side and along the solid coal side of the bottom floor rock mass along the two sides of the working face. Among them, the bottom floor rock mass along the solid coal side has the largest damage scale with a depth of about 30 m. At a position of 12 m under the floor and 8 m in the inner staggered transportation lane, the energy density value of the surrounding rock is between 5-50 J/m2. Combined with the monitoring results of the surrounding rock deformation of the roadway, it is considered that the bottom pumping lane is located at this position and the mining disturbance is lower; the pumping roadway is located directly below the transport roadway or outside the transport roadway. The energy density of the surrounding rock release is greater than 100 J/m2, and the degree of disturbance is high. The numerical simulation results show that the bottom slot is located in the pressure relief area of the floor when the staggered groove is 8 m, which is located directly below the groove and is in the stress concentration area when the staggered groove is outside.

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Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The mining activities of ion⁃type rare earth have caused extremely ecological disturbances on the surface of the mining area and caused local ecological and environmental problems. The variation of surface thermal environment in the mining area can better reflect the ecological disturbance characteristics of the mining area, and is an important parameter to identify surface ecological disturbances. The ion⁃type rare earth area has the characteristics of scattered ore and small single⁃site area, thus obtaining the surface temperature data with strong practicability and higher spatial resolution is valuable to the monitoring of the eco⁃ logical environment of the rare earth mining area. We constructed a temperature downscale model with image fusion and spectral unmixing. The Lingbei ion⁃type rare earth district in Dingnan County of Ganzhou City is selected as the study area. The Landsat 8 satellite image is used as main data source. Firstly, we select data of two seasons in the same year,and combine the integrated image fusion algorithm and linear spectral mixture model . The surface temperature resolution of the surface is downscaled to 15m. Then, the land surface temperature results after downscaling are qualitatively and quantitatively analyzed and tested for accuracy. The results show that the spatial distribution of the surface temperature and the overall trend of the mining area before and after the decomposition are consistent. The surface temperature after the down⁃scaling can reflect the surface features and spatial differences of the mining area in more details. The overall root mean square error （RMSE） of the two seasonal phases in the study area are respectively for 1.459 K and 1.196 K, the mean absolute error （MAE） are 1.128 K and 0.952 K respectively with high accuracy. Our proposed method has high applicability for improving the spatial resolution of the surface temperature of the ionic rare earth. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reverse fault will slip with workface excavation in footwall. As the stresses loading on the combined sample were equal in the X and Y direction, the stress and strain along the fault,as well as acoustic emission signals,were monitored during the coal excavation. The analytical results show that stress decrease zone,stress increase zone and in situ stress zone occurred around the gob and their evolution will cause fault slip. Compared with normal fault, reverse fault has higher slipping risk under the same mining condition. As the workface locating in the footwall of reverse fault advances forward,the ratio of vertical force and horizontal force caused by mining increases from 1 to 6 ,which means the slipping risk of reverse fault rise. The strain along the fault face is not even,and the strain of coal seam is higher than that of rock strata. The energy of 84% of the acoustic events caused by coal mining are between 10-13 J and 10-10 J and their focus mainly concentrate in the roof strata and unlikely transpass the fault face which means the fault can cut-off the stress disturbance of mining. The conjunction of coal seam and fault face tends to cause large acoustic events which means this area has high slip risk. Compared with the in situ seismicity in Zhaolou Coal Mine,the spatial location of seismic focus and experimental acoustic focus have similar features to some extent, which could prove the feasibility of the experimental method adopted in this paper. [ABSTRACT FROM AUTHOR]

In order to study the Coulomb stress variation along a fault face and the tremor distribution features under the mining disturbance,the elements which have effects on Coulomb stress of fault face were theoretically analysed on the basis of the geological and mining conditions of 1303 top-caving workface in Zhaolou Coal Mine,China.With numerical simulation and laboratory test,the Coulomb stress of different location along a reverse fault face was calculated as the distance between mining face and fault face decreasing.Additionally,the in-situ tremor data was collected and statistically analysed.The results show that the Coulomb stress (f) of a fault face point is determined by the mining disturbance (including σx,σy,τxy and τyx),the angle of the fault (θ) and the frictional coefficient (μ) of the fault face.If the mining disturbance and frictional coefficient are fixed,the most dangerous angle of the fault for sliping could be obtained by df/dθ=0.Stress disturbance circle and displacement disturbance circle are formulated as the coal excavating,and the symmetry of the stress disturbance circle and the continuity of the displacement disturbance circle are broken because of the existence of fault.Numerical simulation data and laboratory test data all show that the upper zone of the fault face is influenced by the mining firstly,and the slipping liability of fault increases first and then decreases as the workface mining forward to the fault face.The daily frequency of tremors was about 20 per day as the workface located in footwall and increased to approximately 35 per day when the workface located in the hanging wall.However,the average energy for each tremor declined from 22 kJ before workface reach the fault to 4 kJ after the workface passes the fault,which demonstrates that the tremor disturbance is severe as the workface moving forward to the fault,what is more,the concentration zone of tremor focus transfers from upper zone of the fault to down zone when the mining face mining through the fault face. [ABSTRACT FROM AUTHOR]

Reconstruction of temporal and spatial patterns of land use and cover change by long time series data analysis can provide an important data support for the quantitative study of ecological processes and the evaluation of ecosystem services value at regional or global scale. Taking the Appalachian coalfield segment in Wise County as a study area, based on 22 Landsat TM / ETM + images, the authors reconstructed the dynamic change characteristics of LUCC in 27 years by time-series remote sensing method with both Integrated Forest Z-score (IFZ) and Normalized Difference Vegetation Index (NDVI). Compared to traditional LUCC study, the authors delineated the LUCC types by time-serial trajectory as persisting forest (PF), persisting other vegetation (POV), persisting non-vegetation (PNV), ever mined (EM) and other disturbance (OD), and analyzed their spatial distribution characteristics. The overall classification accuracy and Kappa coefficient are 85.9% and 0.852 respectively. PF, POV, PNV, OD and EM account for 66.68%, 5.15%, 0.24%, 3.63% and 23.67% of the study area. With the decrease of coal yield in these years, EM-land growth rate decreased. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Surrounding rock has a disturbance-resist strength. It will be sensitive to outside disturbance when concentrated stress is higher than its disturbance-resist strength. A disturbance effected zone will be formed in surrounding rock. Deep tunnel's long-term large deformation and instability under disturbance condition is mainly caused by disturbance effected zone's persistently developed towards interior surrounding rock. Aimed at deep rock development roadway, the authors proposed a composite supporting technology which put the concrete-filled steel tubular stent as main subject. The concrete-filled steel tubular stent had advantages such as higher bearing capacity and stable structure. It can provide a larger supporting strength to enhancing surrounding rock's disturbance-resist strength in disturbance effected zone. Preventing disturbance effected zone's development. According to deep tunnel's geological conditions of a coal mine, designed the concrete-filled steel tubular stent is made up by φ194x8 steel and C40 grade concrete. This supporting system can provide more than 1.26 MPa supporting strength. And its application effect is well. [ABSTRACT FROM AUTHOR]

Based on the case of coal mining under Jinsha River in Gansu Province, and focused on the anti-seepage control of the mining disturbed riverbed, by making use of surface movement monitoring and discrete element numerical simulation, the study revealed the regularity of surface movement, the failure characteristics of strata and the percolation path induced by mining underneath the river. A flexible anti-seepage scheme, Four Element Structure ( FES ), was put forward,which can harmonize and buffer the mining induced deformation. From bottom to top,FES consists as follows; reinforcement layer plays the roles of strengthening the riverbed, buffering the deformation, and enhancing the riverbed integrity; bedding subgrade prevents the anti -seepage layer from folding damage due to dislocation and sharpness in riverbed, meanwhile, it can absorb localized deformation; anti-seepage layer is a main anti-seepage structure made by geomembrane with a high strength, good flexibility and ductility; protective layer has a function to fix and protect the anti-seepage layer. In addition, the design principles for the river path in plane, longitudinal and cross-sectional shape of the riverbed were established and a comprehensive mobilized seepage control system was put forward. [ABSTRACT FROM AUTHOR]