scholarly journals Design of Longwall Coal Pillar for the Prevention of Water Inrush from the Seam Floor with Through Fault

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ang Li ◽  
Bing nan Ji ◽  
Qiang Ma ◽  
Chaoyang Liu ◽  
Feng Wang ◽  
...  
Keyword(s):  
Limit Equilibrium ◽  
Water Pressure ◽  
Water Inrush ◽  
Coal Pillar ◽  
Mining Area ◽  
Mine Safety ◽  
Engineering Practice ◽  
Confined Water ◽  
Line Field ◽  
Safety Regulations

Setting up a waterproof coal pillar is an important measure to prevent water inrush from the Weibei mining through fault floor. Based on the plastic slip line field theory, a mechanical model of floor water inrush induced by confined water in the through fault zone was established. The mechanical expressions of confined water pressure and the width of the waterproof coal pillar under the state of limit equilibrium were derived. Combining the laws of floor deformation, failure and fault activation under two kinds of coal pillar width, the safety width of the waterproof coal pillar was determined. Furthermore, the safety threshold is better than the empirical value mentioned in the “coal mine safety regulations.” Following this, grouting transformation was carried out on the K2 sand layer of the cut roadway floor. This provided a theoretical basis and engineering practice for water disaster prevention and the control of the structural floor under similar conditions in the Weibei mining area for future benefit.

scholarly journals Study on the mechanism of water inrush in the arid western mining area

2019 ◽  
Vol 118 ◽  
pp. 03008
Author(s):  
Chao Zheng ◽  
Lan Yu ◽  
Jiangyi He ◽  
Fengfeng Yang ◽  
Jufeng Zhang
Keyword(s):  
Large Scale ◽  
Water Pressure ◽  
Water Inrush ◽  
Hydrodynamic Pressure ◽  
Mining Area ◽  
Mining Areas ◽  
Isolation Layer ◽  
Working Face ◽  
Combined Action ◽  
Tension Fracture

The analysis found that the coal mining process in the western mining area has the mining loss and disaster effect of the water-rich aquifer of the coal seam roof, which is mainly manifested by the overburden water in the roof. On this basis, the formation and development of the separation water of the roof is proposed, and the mechanism of the water inrush from the layer is revealed. It is found that there is hydrostatic pressure and hydrodynamic pressure in the separated water, under the combined action of bed separation water pressure, the mining-induced fracture and water-isolation layer tension fracture are connected, which causes water inrushing in the coal working face of the mine, and provides a theoretical guarantee for the large-scale development of coal resources in western mining areas.

scholarly journals Mechanical Mechanism of Hydraulic Fracturing Effect Caused by Water Inrush in Tunnel Excavation by Blasting

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Quan Zhang ◽  
Jiong Wang ◽  
Longfei Feng
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Inrush ◽  
In Situ Stress ◽  
Confined Water ◽  
Shear Damage ◽  
Splitting Factor ◽  
Blasting Excavation

When the deep tunnel is excavated, the pressure of the confined water is relatively high, causing the water inrush to have a hydraulic fracturing effect. The method of theoretical analysis was adopted to study this effect. A mechanical model for fracturing water inrush under blasting excavation conditions was established. The water inrush under this condition is the result of the combined action of static load (water pressure and in situ stress) and dynamic load (explosive stress wave). According to whether the normal stress on the hydraulic crack surface was tensile stress or compressive stress, two types of water inrush were proposed: water inrush caused by tensile-shear damage and water inrush caused by compression-shear damage. These two types of critical water pressures were calculated separately. The relationship between critical water pressure, in situ stress, and blasting disturbance load was given, and a pore water pressure splitting factor was introduced in the calculation process. The theoretically obtained critical water pressure had been verified in the case of water inrush in a deep-buried tunnel. The established theory can guide field practice well.

scholarly journals Failure Characteristics and Confined Permeability of an Inclined Coal Seam Floor in Fluid-Solid Coupling

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Jian Sun ◽  
Lianguo Wang ◽  
Guangming Zhao
Keyword(s):  
Stress Concentration ◽  
Coal Seam ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Inrush ◽  
Equivalent Stress ◽  
Confined Aquifer ◽  
Confined Water ◽  
Floor Water Inrush ◽  
Failure Depth

Secondary development of FLAC3D software was carried out based on FISH language, and a 3D fluid-solid coupling numerical calculation model was established for an inclined seam mining above a confined aquifer in Taoyuan Coal Mine. A simulation study was implemented on the mining failure depth of an inclined coal seam floor, conducting height of confined water, and the position of workface floor with easy water inrush during advancement of workface. Results indicated that, during the advancement of the inclined coal seam’s workface, obvious equivalent stress concentration areas existed in the floor strata, and the largest equivalent stress concentration area was located at the low region of workface floor. When the inclined coal seam workface advanced to about 80 m, the depth of floor plastic failure zone reached the maximum at approximately 15.0 m, and the maximum failure depth was located at the low region of the workface floor. Before the inclined workface mining, original confined water conducting existed on the top interface of the confined aquifer. The conducting height of the confined water reached the maximum at about 11.0 m when the workface was pushed forward from an open-off cut at about 80 m. Owing to the barrier effect of the “soft-hard-soft” compound water-resistant strata of the workface floor, pore water pressure and its seepage velocity in the floor strata were unchanged after the workface advanced to about 80 m. After the strata parameters at the workface floor were changed, pore water pressure of the confined water could pass through the lower region of the inclined workface floor strata and break through the barrier of the “soft-hard-soft” compound water-resistant strata of the workface floor and into the mining workface, resulting in the inclined coal seam floor water inrush. Results of this study can provide a basis for predicting, preventing, and governing the inclined coal seam floor water inrush above confined aquifer.

Numerical Analysis for the Influence of Mining Deep Coal Seam on Oversize Normal Fault

2014 ◽  
Vol 1073-1076 ◽  
pp. 2112-2116
Author(s):  
Xin Xian Zhai ◽  
Shi Wei Zhang ◽  
She Jun Ma ◽  
Guang Sen Li
Keyword(s):  
Coal Seam ◽  
Abutment Pressure ◽  
Water Inrush ◽  
Coal Pillar ◽  
Normal Fault ◽  
Mine Safety ◽  
Coal Face ◽  
Safety Production ◽  
Floor Water Inrush ◽  
The Stability

The F2 fault Guo in Tianyu Coal Mine belongs to the oversize normal fault, and mining deep coal seam has an influence on the floor water-inrush. Therefore, study the reasonable width of the fault protected coal pillar is a great significance for the mine safety production. With different advance distances of coal face into the fault hangingwall, the authors, by FLAC numerical calculation, studied the characteristics of plastic zone and stress field in front of the coal face. The results show that influence zone scope of moving abutment pressure is about 70~ 80m. The fault is still in the pressure-relief area when it is in the moving abutment pressure zone. The conclusion is conducive to the stability of F2 fault Guo, to prevent the floor from water-inrush, when the reasonable coal pillar width of the fault is wider than 80m.

Study on Numerical Simulation and Safety Analysis of Floor Water Inrush above Confined Water in Deep Mine

2012 ◽  
Vol 616-618 ◽  
pp. 267-271
Author(s):  
Jian Jun Shen ◽  
Wei Tao Liu ◽  
Yun Juan Liu
Keyword(s):  
Numerical Simulation ◽  
Water Pressure ◽  
Water Inrush ◽  
Continuum Theory ◽  
Imaging Method ◽  
Confined Water ◽  
Floor Rock ◽  
Deep Mine ◽  
Fractured Zone ◽  
Water Bursting

Mine water accident due to the mining above confined water is one of the main factors which affects and threatens safety in the coal production, especially for deep mine. Finding out the mine hydrogeological conditions, deepening the research of water inrush mechanism, and taking the effective safety measures of water bursting prevention, are all the key issues of mining under water pressure safely. Based on fractured rock mass equivalent continuum theory, according to drilling imaging method and water pressure test in borehole, in this paper we focus on discussing the water inrush of the floor rock , determining the floor rock permeability tensor with correction method and simulating the floor inrush problem by coupling stress field and seepage field theory and using anisotropic seepage model with FLAC3D. The results show that, the depth of destroyed floor in normal area and fractured zone in fault are about 30m and 58m respectively. According to empirical equation and numerical simulation, we get the results that the effective protection layer thicknesses are 82m and 115m respectively, and it has presented dangers in fault fractured zone based on the water bursting coefficient method.

scholarly journals Deformation and Stress Distribution of the Effective Water-Resisting Rock Beam under Water-Rock Coupling Action inside the Panel Floor

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Baojie Fu ◽  
Hualei Zhang ◽  
Min Tu ◽  
Xiangyang Zhang
Keyword(s):  
Elastic Modulus ◽  
Virtual Work ◽  
Water Pressure ◽  
Water Inrush ◽  
Confined Water ◽  
Analysis Model ◽  
Floor Rock ◽  
The Stability ◽  
Effective Water ◽  
Rock Beam

The stability of panel floor, which is above confined water, is the key to determine the water inrush from the panel floor. Based on the characteristics of “lower three zones” of the panel floor, the mechanics analysis model of a floor water-resisting rock beam is established. Then, by the principle of virtual work and energy functional variational conditions, the trends of deflection and internal stress are researched in the effective water-resisting rock beam under the combined action of mining stress and water pressure. And how to determine its stability is acquired. According to the geological and mining conditions of A3 coal seam in Panxie mining area of Huainan Mining Group, three factors influencing on the stability of the floor rock beam are analyzed, such as elastic modulus, coefficient of viscosity, and water pressure. It is shown that the elastic modulus plays the most important role on the deformation of the rock beam. So, for improving the mechanical properties of the rock beam, the reinforcing floor technique has been proposed. On the one hand, it is contributed to improve the ability for resisting floor deformation. On the other hand, it can increase the coefficient of rock viscosity in water damage zones and reduce the speeds of loading and deformation in the whole rock beam. Hydrophobic decompression can effectively reduce the stress on the boundary of the rock beam, and the stability is enhanced. The research results have a guiding significance for determining whether there are water inrush risks in the panel above the confined aquifer.

scholarly journals Prevention of Water Inrushes in Deep Coal Mining over the Ordovician Aquifer: A Case Study in the Wutongzhuang Coal Mine of China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Huichao Yin ◽  
Bin Xu ◽  
Shangxian Yin ◽  
Wuzi Tian ◽  
Hui Yao ◽  
...  
Keyword(s):  
Coal Mining ◽  
Prevention And Control ◽  
Water Pressure ◽  
Water Inrush ◽  
Mining Area ◽  
Full Time ◽  
Time Space ◽  
And Control ◽  
Ternary Structure

Through field observation and theoretical study, we found that the Hanxing mining area has a typical ternary structure in coal mining under high water pressure of the aquifer. This ternary structure is the Ordovician limestone aquifer-aquiclude including thin limestones-coal seam. Although the aquiclude is considerably thick, there is still a great risk of water burst during mining under water pressure in the deep burial environment. Multidimensional characteristics of floor water inrush in deep mining are summarized in the paper, including water migration upwardly driven by the Ordovician confined water, the planar dispersion of the water inrush channel, the stepped increase of the water inrush intensity, the hysteretic effluent of the water inrush time and the exchange, and adsorption of the water quality. The water inrush mechanism is clarified that the permeability, dilatancy, fracturing, and ascending of the water from the Ordovician limestone aquifer form a planar and divergent flow through the transfer, storage, and transportation of thin limestone aquifers. The corresponding water inrush risk evaluation equation is also proposed. Based on the thickness of the aquiclude, the thickness of the failure zones, and the water inrush coefficient, the floor aquiclude is classified into five categories. While water inrush cannot be completely controlled by the traditional underground floor reinforcement with ultra-thick aquiclude or even zonal grouting, a comprehensive prevention and control concept of the four-dimensional floor water hazard in full time-space domain are proposed. A tridimensional prevention and control model of three-dimensional reticulated exploration, treatment, verification, and supplementation is presented. A full time domain technological quality control process of condition assessment, exploration, remediation, inspection, evaluation, monitoring, and reassurance is formed, and a water disaster prevention method with full time-space tridimensional network in deep coal mining is established. Case study in the Hanxing mining area demonstrates that the proposed methods are highly effective.

scholarly journals Simulated Experiment of Water-Sand Inrush across Overlying Strata Fissures Caused by Mining

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Guibin Zhang ◽  
Hailong Wang ◽  
Shenglei Yan ◽  
Chuanyang Jia ◽  
Xiaoyuan Song
Keyword(s):  
Water Pressure ◽  
Test System ◽  
Mine Safety ◽  
Water Yield ◽  
Support Pressure ◽  
Confined Water ◽  
Working Face ◽  
Unconsolidated Sand ◽  
Seam Mining ◽  
Overlying Strata

In western region of China, the water-sand inrush across overlying strata fissures caused by mining threatens the mine safety production seriously. In order to study the development of water-sand inrush across overlying strata fissures caused by mining, a simulated test system consisted of load support bracket, laboratory module, confined water module, coal seam mining simulator, storage tank, and control system is developed. The combination of coal bearing strata in the south of Shendong mining area is looked on as the engineering background, and a series of new nonhydrophilic composite materials with lower intensity are developed to simulate the coal measure strata. The excavation of physical model can reproduce the whole process of water-sand inrush across overlying strata fissures caused by mining to the life. Under the action of mining and water pressure, after the fourth excavation, the mining-induced vertical fractures of overlying strata pass through the entire bedrock and connect the unconsolidated sand bed, which serves as pathways between the unconsolidated sand bed and working face, triggering water-sand inrush. The water pump suddenly accelerates, and the water yield suddenly increases to the extreme value of 150 L/h. The water pressure rapidly drops to 0 MPa, and a small amount of colored sand enters into the fractures of overlying strata and flows out with the water. The distribution of support pressure around the working face can be divided into 4 areas obviously, that is, the original stress area, the stress-concentrated area, the stress-released area, and the stress restoration area. Test results show that the system is stable and reliable, which have important significance for studying the formation mechanism of water-sand inrush across overlying strata fissures further.

The Analysis of the Coal Floor Water Inrush Effected by the Fault

2014 ◽  
Vol 535 ◽  
pp. 626-630
Author(s):  
Yun Xun Zhang ◽  
She Rong Hu ◽  
Ji Chao Peng ◽  
Xue Qing Zhang
Keyword(s):  
Water Pressure ◽  
Water Inrush ◽  
Bottom Layer ◽  
Geological Structure ◽  
Mine Pressure ◽  
Confined Water ◽  
Working Face ◽  
The Face ◽  
Pressure Water ◽  
Floor Water Inrush

Water inrush from coal floor is some kind of complex geology and mining phenomenon. It is the confined water underlying the coal seams breaking the barrier of the bottom layer, and the water runs into the face of mine in emergencies or delayed, causing natural disasters like discharge increases or flooding. According to the previous studies on water inrush, the water inrush is a joint result of geological structure, water pressure, mine pressure, water-resisting floor and mining of working face. The thesis focuses on the influence of geological fault on the water-inrush from coal floor and analyses the controlling effects of fault property and non-water conducted fault activation of water in order to provide a reference or significance for the analysis of water-inrushs genesis mechanism.

scholarly journals Research and application of L-shaped ground well gas drainage technology in mining area

2021 ◽  
Vol 329 ◽  
pp. 01020
Author(s):  
Junhui Fu
Keyword(s):  
Gas Flow ◽  
Production Efficiency ◽  
Drainage System ◽  
Fracture Morphology ◽  
Mining Area ◽  
Gas Production ◽  
Mine Safety ◽  
Gas Content ◽  
Engineering Practice ◽  
Overburden Rock

By law mining fracture morphology analysis, based on coal face gas flow characteristics, obtain the L-shaped surface well layout area in the mining area under the influence of mining. Analysis of overlying strata "three zones" distribution, the calculation method of the height of overburden rock "three zones" designed in mining area ground well structure proposed safety drainage system construction plan. In Sihe Mine was L-shaped ground mining area well engineering practice, the average gas production at a concentration of 80%, with an average drainage net amount 22 000 m3 / d, a total of more than 300 days running, drainaging 6.5 million CBM m3. After the implementation of drainage work surface corner gas content fell 46.5%, to effectively improve production efficiency, for the surface treatment gas play a key role. Successfully removed Mining Face Gas for safe production constraints, to protect the mining of coal mine safety, and achieved good social and economic results, with good promotional value.

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