scholarly journals Experimental Study on the Mining-Induced Water-Resistance Properties of Clay Aquicludes and Water Conservation Mining Practices

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhenli Fan ◽  
Kesong Fan ◽  
Zhiguo Liu ◽  
Yutong Feng ◽  
Hua Wei ◽  
...  
Keyword(s):  
Water Conservation ◽  
Crack Opening ◽  
Soil Layer ◽  
Coal Pillar ◽  
Protective Layer ◽  
Physical And Mechanical Properties ◽  
Mining Area ◽  
Clay Layer ◽  
Working Face ◽  
Mining Water

The Yushen mining area contains thin bedrock and a shallow buried coal seam, where JingLe group Hipparion clay and Lishi loess serve as a high-quality cement insulation cover. This study investigates the properties of the clay layer to determine the effect of the clay aquiclude on the mining water variation and fracture characteristics. Unloading hydraulic jack experiments were performed to test the physical and mechanical properties of the clay layer and the structure was analyzed in detail. The experimental results show that mining affects the soil cracks, leading to crack opening and subsequent bridging. The permeability coefficient of the soil layer initially increases with increased unloading and then decreases. A theoretical model is developed to determine the recovery mechanism of the clay layer water insulation based on the spatial movement of the clay. The results indicate the formation of a waterproof cover type of coal mud protection. Design methods are proposed to optimize the coal pillar size. Mining damage leads to the formation of a mud-covered bridge belt, which can be designed to appropriately reduce the protective layer thickness. The model is applied to the Hao Jialiang 2301 working face. The results provide important insight on the variation characteristics of the mining water insulation in clay layers and an important reference for accurately calculating the size parameters of waterproof protective coal pillars under mud-cap conditions to increase the upper mining limit of the working face.

scholarly journals Application of Roadway Backfill Mining in Water-Conservation Coal Mining: A Case Study in Northern Shaanxi, China

2019 ◽  
Vol 11 (13) ◽  
pp. 3719 ◽  
Author(s):  
Yihe Yu ◽  
Liqiang Ma
Keyword(s):  
Water Resources ◽  
Coal Mining ◽  
Groundwater Level ◽  
Water Conservation ◽  
Coal Pillar ◽  
Normal Growth ◽  
Mining Area ◽  
Backfill Mining ◽  
Northern Shaanxi ◽  
The Stability

The mining induced subsidence and strata deformation are likely to affect the stability of the aquiclude, resulting in loss of water resources in the mining area. In order to reduce the disturbance of coal mining to the overlying strata and to preserve the water resources in the coal mining area, the roadway backfill mining (RBM) method was trialed in Yuyang coal mine in Northern Shaanxi, China. Based on pressure arch theory and ultimate strength theory, a mechanical model was developed to analyze the stability of coal pillars. Then the maximum number of vacant roadways between the mining face and the backfilling face was determined according to the stability of coal pillar and filling body. The method to calculate aquiclude subsidence and deformation was also proposed. Furthermore, as indicated by FLAC3D numerical simulations, the maximum tensile stress subjected by the aquiclude was 0.14 MPa, which is smaller than its tensile strength; the horizontal deformation was 0.24 mm/m, which is also smaller than the critical deformation of failure. Field monitoring data demonstrated a maximum of 2.76 m groundwater level drop in the mining area after mining. The groundwater level was determined to be 4.45~10.83 m below surface, ensuring the normal growth of surface vegetation and realizing the water-conservation coal mining (WCCM).

Study on the Terminal Line Reasonable Position of Two Coal Seam under the Down-Protective Layer Pressure-Relieved Mining

2013 ◽  
Vol 295-298 ◽  
pp. 2913-2917
Author(s):  
Xiang Yang Zhang ◽  
Min Tu
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
Protective Layer ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Rock Properties ◽  
Engineering Practice ◽  
Working Face ◽  
Roadway Deformation ◽  
The Impact

In order to study the stress distribution and its dynamic influence law while the protective layer mining, based on the transfer law of mining-induced stress in the coal seam floor and in front of the working face, using numerical simulation software to simulate the surrounding rock stress under the different pillar width mining conditions, and carried through the roadway deformation engineering practice observations. It is shown that reserved 110m coal pillar could weaken the impact on the front of the floor tunnel under the protective layer mining process. When the top liberated layer mining to reduce the impact of mining stress superposition, it should avoid the terminal lines on the two coal seams at the same location and may be staggered at least about 30m ~ 50m. And it obtained that the roadway deformation not only by mining impact, but also considering the geological environment surrounding rock conditions, tunnel position in which layers of rock, rock properties and other factors. The research guided the engineering practice successfully.

scholarly journals Characteristics of Pressure Relief Gas Extraction in the Protected Layer by Surface Drilling in Huainan

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaozhang Tong ◽  
Hu Wen ◽  
Xiaojiao Cheng ◽  
Shixing Fan ◽  
Chunhui Ye ◽  
...  
Keyword(s):  
Flow Rate ◽  
Protective Layer ◽  
Periodic Variation ◽  
Mining Area ◽  
Gas Content ◽  
Gas Extraction ◽  
Pressure Relief ◽  
Working Face ◽  
Extraction Volume ◽  
Extraction Processes

To study the behavior of gas extraction from the protected layer by surface drilling, the common characteristics of gas extraction concentration and gas extraction quantity are summarized through the collection of key parameters of surface drilling and a combination of data and figures, with the background of 11−2 coal protection 13−1 coal in the Huainan mining area. The research results show that the flow of pressure relief gas extraction of the protected layer by surface drilling has three stages: a rising period, stable period, and decay period. When the extraction processes of multiple surface wells on the same working face are coordinated, the extraction flow is superimposed, and the extraction volume of surface drilling shows an increasing trend and fluctuates with the location of the drilling. The extraction flow rate before ground drilling is relatively small, and the extraction flow rate increases after ground drilling. This behavior is further confirmed by field observation of mining changes in the protective layer and the expansion and deformation of the protected layer. The periodic variation in the surface drilling and extraction quantity is affected primarily by the mining movement of the working face of the protective layer. Specifically, it is affected by factors such as the mining progress of the working face of the protective layer, mining height, degree of compacted goaf, degree of pressure relief of the protected layer, original gas content, and other measures taken to extract the protected layer.

scholarly journals Research and Practice of Comprehensive Utilization Technology of Mine Water Based on Green Mining

2021 ◽  
Vol 245 ◽  
pp. 01007
Author(s):  
Li Wang ◽  
Yongzhi Fu ◽  
Jingyan Zhu
Keyword(s):  
Mine Water ◽  
Water Conservation ◽  
Mining Area ◽  
Utilization Rate ◽  
Domestic Water ◽  
Mining Technology ◽  
Working Face ◽  
Management Optimization ◽  
Technical Plan ◽  
Surface Production

Yannan Coal Mine in Dayan Mining Area creatively utilizes water-preserving mining technology to block abandoned roadways to build underground reservoirs and build underground sedimentation tanks. It implements a zoned utilization and zoned management optimization technical plan for mine water, so that it can meet the needs of underground working face production and surface production and domestic water use. This mine water comprehensively recycles water conservation mining technology and makes full use of mine water resources. This greatly improves the utilization rate of mine water, realizes the recycling of mine water, and accelerates the construction of green mines.

scholarly journals Mechanism of Coal Bump among Mine Group under the Control of Large Geological Body: A Case Study of Yima Mining Area, China

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yizhe Li ◽  
Shankun Zhao ◽  
Qingxin Qi ◽  
Pengzhi Pan ◽  
Xiangzhi Wei ◽  
...  
Keyword(s):  
Coal Pillar ◽  
Vertical Direction ◽  
Mining Area ◽  
Horizontal Stress ◽  
Active Movement ◽  
Geological Body ◽  
Coal Bump ◽  
Working Face ◽  
Whole Space ◽  
Thick Overburden

Coal bump often occurs in coal mining among many working faces in mine group under the control of large geological bodies. In order to study the coal bump mechanism between adjacent working faces under the conditions of large fault and huge thick overburden conglomerate, this paper regards Yima mining area as a practical engineering background and theoretically analyzes the mechanical behavior of overlying rock in the spatial structure. Then, the deep-ground and whole-space measurement is carried out in the 13230 working face of Gengcun mine and 21121 working face of Qianqiu mine. The results show that the basic structural unit in Yima mining area is composed of two goafs, middle coal pillar, and overlying conglomerate. Under the condition of nonsynchronous mining in adjacent working faces, there is a comovement effect similar to lever’s “prying” phenomenon in thick conglomerate beam—the conglomerate strata above larger goaf side induce an overall uplift movement of the corresponding strata above smaller goaf side, and uplift length of the conglomerate strata is related to the mining length, coal pillar width, caving angle, and coal-conglomerate distance. The results of surface subsidence, microseism, and stress in the two working faces verify the conglomerate’s phenomenon of comovement effect and disturbance range and further explain the role of active movement of F16 fault and overall causes of huge thick conglomerate on the coal bump. The vertical stress of the 13230 face is relatively low at the beginning, and high horizontal stress by fault activation causes typical bump accident with the horizontal sliding of coal body. With the increasing development of 13230 face, the intensity and frequency of coal bump in horizontal direction decrease obviously, but with high proportion in vertical direction. The results provide a theoretical basis for the study on the mechanism of coal bump between two adjacent working faces under the conditions of huge thick conglomerate and large thrust fault.

Key Technology of Safety and Effective Mining in Thick Coal Seams with Dirt Band

2011 ◽  
Vol 201-203 ◽  
pp. 417-420 ◽  
Author(s):  
Wei Dong Pan ◽  
Hong Bao Zhao ◽  
Sheng Li Yang
Keyword(s):  
Economic Benefit ◽  
Reference Value ◽  
Physical And Mechanical Properties ◽  
Mining Area ◽  
Geological Condition ◽  
Research Subject ◽  
Important Research ◽  
Coal Seams ◽  
Key Technology ◽  
Working Face

It is an important research subject to realize safety and effective mining with the top-coal caving method in complicated geological condition. Based on the bad occurrence conditions and thick dirt band between No.8 and No.9 coal seams of Zhuxianzhuang coal mine in Huaibei mining area, the physical and mechanical properties of dirt band were analyzed, the fracture mechanism of dirt band was studied, caving laws of roof and top coal were summarized, and optimal caving technology of coal was designed and adopted. The results show that the safety and effective mining has been realized in thick seams working face of dirt band, and good economic benefit was achieved. The research results have certain guiding significance and reference value to thick seams mining under similar conditions.

Stress Evolution and Deformation Control Technology for Deep Mining Influenced Roadway

2011 ◽  
Vol 90-93 ◽  
pp. 137-145
Author(s):  
Jia Guang Kan ◽  
Nong Zhang ◽  
Hai Wei Zhang ◽  
Zhi Yi Zhang ◽  
Guang Yao Si
Keyword(s):  
Coal Pillar ◽  
Surface Displacement ◽  
Mining Area ◽  
Surrounding Rock ◽  
Stress Evolution ◽  
Deformation Control ◽  
Working Face ◽  
Geological Conditions ◽  
Basic Ideas ◽  
Roadway Deformation

In order to effectively control deep roadway under mining influence, based on the typical engineering geological conditions of Dingji coalmine in Huainan mining area, we researched on the laws of stress evolution and failure mechanism of roadway influenced by working face advancing by using numerical simulation and applying field test. The results showed that the surrounding rock stress of roadway ribs increased gradually with face advancing, vertical stress peak transfer to in-depth of roadway surrounding rock, the trend of roadway surface displacement variation consistent with corresponding stress variation. An appropriate coal pillar size (105 m) was proposed. We put forward the basic ideas for surrounding rock controlling and surrounding rock reinforce technology, namely U-steel support back grouting and bolt-cable cooperative supporting. By roadway deformation, roof layer separation and borehole detecting, we found out that displacement of roadway ribs was less than 250 mm, subsidence of roof was less than 110 mm, and the roadway deformation has been effectively controlled.

Freezing Pressure and its Influencing Factors of Deep Clay Layer in the Huainan Mining Area

2012 ◽  
Vol 170-173 ◽  
pp. 836-841
Author(s):  
Wei Shao ◽  
Bin Lin
Keyword(s):  
Coal Mine ◽  
Good Description ◽  
Mining Area ◽  
Frost Heave ◽  
Dynamic Monitoring ◽  
Clay Layer ◽  
Formation Pressure ◽  
Closed Systems ◽  
Permanent Formation ◽  
Layer Deformation

Gu Bei coal mine deep shaft freezing pressure of calcareous clay dynamic monitoring showed that the freezing pressure of the calcareous clay fastest grow in the first 2 weeks after the sidewall concrete pouring , freezing pressure has obvious direction . Analysis showed that the layer of freezing pressure is mainly calcareous clay layer deformation pressure, size and the temperature of well has a positive correlation. Maximum freezing pressure of the deep calcareous clay layer approximate the permanent formation pressure values and the maximum frost heave force determined by the frost heave experiments in indoor closed systems ,the average freezing pressure with depth variation of the exponential function can be used to good description.

scholarly journals Influence of pore water pressure change on consolidation behavior of saturated poroelastic medium

2020 ◽  
Vol 382 ◽  
pp. 375-379
Author(s):  
Chao-Lung Yeh ◽  
Wei-Cheng Lo ◽  
Cheng-Wei Lin ◽  
Chung-Feng Ding
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Saturated Porous Medium ◽  
Water Pressure ◽  
Soil Layer ◽  
Pressure Change ◽  
Clay Layer ◽  
Poroelastic Medium ◽  
Total Settlement ◽  
Consolidation Behavior

Abstract. There are many factors causing land subsidence, and groundwater extraction is one of the most important causes of subsidence. A set of coupled partial differential equations are derived in this study by using the poro-elasticity theory and linear stress-strain constitutive relation to describe the one-dimensional consolidation in a saturated porous medium subjected to pore water pressure change due to groundwater table depression. Simultaneously, the closed-form analytical solutions for excess pore water pressure and total settlement are obtained. To illustrate the consolidation behavior of the poroelastic medium, the saturated layer of clay sandwiched between two sand layers is simulated, and the dimensionless pore water pressure changes with depths and the dimensionless total settlement as function of time in the clay layer are examined. The results show that the greater the water level change in the upper and lower sand layers, the greater the pore water pressure change and the total settlement of the clay layer, and the more time it takes to reach the steady state. If the amount of groundwater replenishment is increased, the soil layer will rebound.

scholarly journals Rebound Mechanism and Control of the Hard Main Roof in the Deep Mining Roadway in Huainan Mining Area

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Denghong Chen ◽  
Chao Li ◽  
Xinzhu Hua ◽  
Xiaoyu Lu ◽  
Yongqiang Yuan ◽  
...  
Keyword(s):  
Slope Angle ◽  
Bending Moment ◽  
Main Roof ◽  
Mining Area ◽  
Calculation Model ◽  
Surrounding Rock ◽  
Tensile Failure ◽  
Damage Area ◽  
Critical Range ◽  
Working Face

Taking the occurrence conditions of the hard main roof in the deep 13-1 coal mining roadway in Huainan mining area as the research object, based on the mechanical parameters of the surrounding rock and the stress state of the main roof obtained by numerical simulation, a simply supported beam calculation model was established based on the damage factor D, main roof support reaction RA, RB, and critical range C (9 m) and B (7 m) at the elastoplastic junction of the solid coal side and mining face side (hereinafter referred to as “junction”). Considering that the damage area still has a large bearing capacity, the vertical stress of the main roof at the junction is K1γH (0.05γh, 0.15γh, and 0.25γh) and K2γH (0.01γh, 0.10γh, and 0.2γh). The maximum deflection is 21 mm, 324 mm, and 627.6 mm, respectively. According to the criterion of tensile failure, the maximum bending moment of the top beam is 209 mN·m at the side of the working face 3.1 m away from the roadway side when K1 = 0.15 and K2 = 0.10, and the whole hard main roof is in tensile failure except the junction. To control the stability of the top beam and simplify the supporting reaction to limit the deformation of the slope angle, RC and RD are used to construct the statically indeterminate beam. By adding an anchor cable and advance self-moving support to the roadway side angle, the problem of difficult control of the surrounding rock with a large deformation of the side angle roof is solved, which provides a reference for roof control under similar conditions.

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