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.

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 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.

scholarly journals Theoretical Research and Numerical Simulation on Water Resistance Mechanism of Textile Bag in Water Passage

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Ang Li ◽  
Yuxuan Yang ◽  
Mingcheng Zhu ◽  
Wenzhong Zhang ◽  
Bingnan Ji ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Water Resistance ◽  
Simulation Analysis ◽  
Water Pressure ◽  
Water Inrush ◽  
Deformation Characteristics ◽  
Water Blocking ◽  
The Stability ◽  
Water Passage

It is an important problem in the mine water disaster prevention and control to control the large passage moving water. Traditional grouting technology is to put coarse aggregate and fine aggregate downward first and then grouting treatment. But the aggregate and cement flow distance is long, consumption is large, cost is high, and easy to appear secondary water inrush. Centering on the technical difficulties in the rapid construction of the blocking body of the moving water passage, a water-blocking textile bag was invented. The purpose of blocking the tunnel water inrush was achieved by grouting inside the bag body, which fundamentally realized the rapid blocking of the large passage through water under the condition of moving water. However, the mechanism, water plugging law, and design parameters of water blocking roadway with textile bag are still unclear. In this paper, the slip law and stability of the textile bag in the moving water and the deformation characteristics caused by the dynamic water pressure are theoretically analyzed and simulated. Through theoretical analysis, the ultimate antihydraulic stress value of a textile bag of a certain specification is calculated, and the parameters of the textile bag that affect the stability of the bag body are also determined. Xflow was used for numerical simulation analysis to study the deformation characteristics of the textile bag under water and the law of water barrier. The simulation analysis focuses on the water resistance effect and flow field distribution characteristics of the textile bag in the water passage under the condition of low flow rate and low pressure, as well as the stability and self-deformation characteristics of the textile bag under the condition of high flow rate and high pressure. The accuracy of the limit resistance to water pressure of the textile bag obtained from theoretical analysis is verified. The results show that the theoretical analysis is consistent with the simulation results. The textile bag can realize the fast controllable plugging of the large water passage of moving water within the limit of the antihydraulic stress.

scholarly journals Fracture Propagation and Hydraulic Properties of a Coal Floor Subjected to Thick-Seam Longwalling above a Highly Confined Aquifer

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Shaodong Li ◽  
Gangwei Fan ◽  
Dongsheng Zhang ◽  
Shizhong Zhang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Longwall Mining ◽  
Water Pressure ◽  
Water Inrush ◽  
Volumetric Strain ◽  
Longitudinal Direction ◽  
Confined Aquifer ◽  
Floor Rock ◽  
Fracture Development ◽  
Mining Disturbance

The high-pressure and water-rich confined aquifer occurring in the Ordovician limestone sequence poses great threats to the routine production of underground longwall mining. Considering the intense cooperation of mining disturbance and water pressure, water-conducting fractures within a coal seam floor can connect the lower aquifer and upper goaf, and this hydraulic behavior is considered the root of water inrush hazard and water loss or contamination. In this paper, the panel 4301 of the Longquan coal mine serves as the case where the panel works closely above the floor with high water pressure. By the combination of physical and numerical modelling approaches, the variation characteristics of fracture development and volumetric strain of floor rocks subjected to mining disturbance are analyzed. A numerical computation model is constructed based on the volumetric strain-permeability equation obtained by curve fitting, and on such basis, the impacts of different mining parameters on floor rock permeability are studied. The results show that the floor rocks experience fracture generation, extension, and convergence procedures as the workface advances along the longitudinal direction, and fractures appearing in front of the workface are more developed. In the whole process of coal seam extraction, the volumetric strain profile exhibits “Λ” shape and an inverted saddle shape before and after overburden strata collapse. By controlling a single variable, the paper reveals that panel height is of greater impact on floor permeability changes than panel length and panel width.

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.

Deterministic Method of Floor Rock Permeability Tensor of Mining over Confined Water and Application in Numerical Simulation

2012 ◽  
Vol 204-208 ◽  
pp. 4840-4844
Author(s):  
Wei Tao Liu ◽  
Jian Jun Shen ◽  
Yun Juan Liu
Keyword(s):  
Coal Mining ◽  
Fractured Rock ◽  
Water Inrush ◽  
Water Injection ◽  
Correction Method ◽  
Permeability Tensor ◽  
Imaging Method ◽  
Confined Water ◽  
Rock Permeability ◽  
Floor Rock

Based on equivalent continuum media theory of fractured rock mass, the author got the permeability tensor of floor strata in some mine according to core logging method, drilling imaging method and boring water injection method, and determined the floor rock permeability tensor using correction method. The author simulated the floor inrush problem by coupling fluid-solid theory and anisotropic flow model with FLAC3D software. The result shows that, the destroyed depth of floor and the confined water rising height are all slight when the coal mining workface is 150m apart from the fault, but they increase obviously when the coal mining workface is 30m apart from the fault, and are extremely easy to get through and casue water inrush through fault.

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 Analysis of Tunnel Water Inrush Considering the Influence of Surrounding Rock Permeability Coefficient by Excavation Disturbance and Ground Stress

2021 ◽  
Vol 11 (8) ◽  
pp. 3645
Author(s):  
Helin Fu ◽  
Pengtao An ◽  
Long Chen ◽  
Guowen Cheng ◽  
Jie Li ◽  
...  
Keyword(s):  
Permeability Coefficient ◽  
Water Pressure ◽  
Water Inrush ◽  
Surrounding Rock ◽  
Water Inflow ◽  
Calculation Error ◽  
External Water Pressure ◽  
Ground Stress ◽  
External Water ◽  
Inflow Prediction

Affected by the coupling of excavation disturbance and ground stress, the heterogeneity of surrounding rock is very common. Presently, treating the permeability coefficient as a fixed value will reduce the prediction accuracy of the water inflow and the external water pressure of the structure, leading to distortion of the prediction results. Aiming at this problem, this paper calculates and analyzes tunnel water inflow when considering the heterogeneity of permeability coefficient of surrounding rock using a theoretical analysis method, and compares with field data, and verifies the rationality of the formula. The research shows that, when the influence of excavation disturbance and ground stress on the permeability coefficient of surrounding rock is ignored, the calculated value of the external water force of the tunnel structure is too small, and the durability and stability of the tunnel are reduced, which is detrimental to the safety of the structure. Considering the heterogeneity of surrounding rock, the calculation error of water inflow can be reduced from 27.3% to 13.2%, which improves the accuracy of water inflow prediction to a certain extent.

scholarly journals Modelling and Stability Analysis of Articulated Vehicles

2021 ◽  
Vol 11 (8) ◽  
pp. 3663
Author(s):  
Tianlong Lei ◽  
Jixin Wang ◽  
Zongwei Yao
Keyword(s):  
Stability Analysis ◽  
Critical Velocity ◽  
Equations Of State ◽  
Steering System ◽  
Analysis Model ◽  
Nonlinear Dynamic Model ◽  
Equilibrium Equations ◽  
Eigenvalue Method ◽  
Articulated Vehicles ◽  
The Stability

This study constructs a nonlinear dynamic model of articulated vehicles and a model of hydraulic steering system. The equations of state required for nonlinear vehicle dynamics models, stability analysis models, and corresponding eigenvalue analysis are obtained by constructing Newtonian mechanical equilibrium equations. The objective and subjective causes of the snake oscillation and relevant indicators for evaluating snake instability are analysed using several vehicle state parameters. The influencing factors of vehicle stability and specific action mechanism of the corresponding factors are analysed by combining the eigenvalue method with multiple vehicle state parameters. The centre of mass position and hydraulic system have a more substantial influence on the stability of vehicles than the other parameters. Vehicles can be in a complex state of snaking and deviating. Different eigenvalues have varying effects on different forms of instability. The critical velocity of the linear stability analysis model obtained through the eigenvalue method is relatively lower than the critical velocity of the nonlinear model.

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