scholarly journals Study on the Stability of Coal Pillars Under the Disturbance of Repeated Mining in a Double-Roadway Layout System

2021 ◽  
Vol 9 ◽  
Author(s):  
Shuaigang Liu ◽  
Jianbiao Bai ◽  
Xiangyu Wang ◽  
Guanghui Wang ◽  
Bowen Wu ◽  
...  

The double-roadway layout system, which is extensively applied in large mines, has the potential to significantly balance excavation-mining and improve mine ventilation and transportation capacity. However, the coal pillar in the double-roadway layout system is easily destabilized due to the disturbance of repeated mining, which has a significant impact on the safety and reliability of coal mines. This paper takes the coal pillar and its supporting structure of the double-roadway layout system as the research object, establishes a UDEC trigon numerical calculation model, and systematically corrects the input parameters, while explaining the excavation method of roadways and the simulation method of the supporting structure element. The numerical simulation results show that under the conventional support intensity conditions, the internal damage of the coal pillar during the excavation period is about 20%, while the internal damage to the coal pillar develops to 55% throughout the first-panel mining. During the disturbance of repeated mining, the damage in the coal pillar increased to 90%, and the coal pillar was already in a state of failure. Under the combined control of rock bolts and counter-pulled anchor cables, the coal pillar damage does not change significantly during the excavation and first-panel mining. During the disturbance of repeated mining, the damage of the coal pillar is reduced to 63%. There is a certain low damage area in the coal pillar, which can ensure the stability of the coal pillar and its supporting structure as a whole. Furthermore, the on-site monitoring results show that the maximum value of the floor-to-roof and rib-to-rib convergence of a W1310 tailgate during the repeated mining disturbance stage is 730 and 620 mm, respectively. The findings of this study give an approach to—as well as estimated values for the design of, including its “small structure” control technical parameters—the double-roadway layout system.

2021 ◽  
Author(s):  
Pan Weidong ◽  
Deng Cang ◽  
Li Boyang ◽  
Zhang Kunming ◽  
Gao Shan

Abstract Unlike general long-wall mining, the roof activity is more intense when long-wall face passes through the abandoned roadway. Technically, the coal pillar between the abandoned roadway and the long-wall face will suddenly fail with a certain critical value of its width, leading to the roof breaks in advance and other production-restricted problems because of the support loss, which will be a great threat to underground mining activities. In order to guarantee a safe mining condition, therefore, it is greatly necessary to uncover how the roof breaks in advance and how to cope with it. From the stability maintaining of the key block perspective, this paper took for research that the 12404-1 long-wall face of Wulanmulun coal mine, China. The critical value of the coal pillar’s width was determined to be about 5m by theoretical analysis, likely, the appropriate support force of the abandoned roadway’s roof is about 4020KN per meter. Meanwhile, a numerical simulation method was adopted to study the ground pressure when the long-wall face passing through the abandoned roadway. Correspondingly, a compound supporting technology involving the roof presplit technique, anchor cable supporting and pumping pillar supporting were proposed for the roof of the abandoned roadway, and it practically worked well.


2013 ◽  
Vol 353-356 ◽  
pp. 2073-2078
Author(s):  
Tian Zhong Ma ◽  
Yan Peng Zhu ◽  
Chun Jing Lai ◽  
De Ju Meng

Slope anchorage structure of soil nail is a kind of economic and effective flexible slope supporting structure. This structure at present is widely used in China. The supporting structure belong to permanent slope anchorage structure, so the design must consider earthquake action. Its methods of dynamical analysis and seismic design can not be found for the time being. The seismic design theory and method of traditional rigidity retaining wall have not competent for this new type of flexible supporting structure analysis and design. Because the acceleration along the slope height has amplification effect under horizontal earthquake action, errors should be induced in calculating earthquake earth pressure using the constant acceleration along the slope height. Considering the linear change of the acceleration along the slope height and unstable soil with the fortification intensity the influence of the peak acceleration, the earthquake earth pressure calculation formula is deduced. The soil nailing slope anchorage structure seismic dynamic calculation model is established and the analytical solutions are obtained. The seismic design and calculation method are given. Finally this method is applied to a case record for illustration of its capability. The results show that soil nailing slope anchorage structure has good aseismic performance, the calculation method of soil nailing slope anchorage structure seismic design is simple, practical, effective. The calculation model provides theory basis for the soil nailing slope anchorage structure of seismic design. Key words: soil nailing; slope; earthquake action; seismic design;


2013 ◽  
Vol 353-356 ◽  
pp. 436-439
Author(s):  
De Sen Kong ◽  
Yong Po Chen

In order to forecast the stability of deep roadway and optimize the parameters of bolts, the complex stress environment and the multivariate surrounding rocks characteristics of deep roadway were analyzed. Then the classification prediction method and the numerical simulation method were simultaneously used to analysis the stability of surrounding rocks. Furthermore, the supporting parameters of bolts were also designed optimally. It was shown that the characteristics of stress distribution, deformation and failure zone of surrounding rocks are not ideal. So it is necessary to optimize the supporting parameters of deep roadway. All these research findings will provide the theory basis for bolts of deep roadway and will ensure the optimization of bolts and the stability of deep roadway in the long run.


2014 ◽  
Vol 716-717 ◽  
pp. 735-738 ◽  
Author(s):  
Peng Cheng ◽  
Jian Zhang ◽  
Ai Qing Liu

Aiming at the current situation of anchor bolt and cable arrangement in mine roadway support, the paper analysis the mechanical characteristics and mechanism of bolts and cables, and numerical simulation method is used to comparison and analysis of pre-tension distribution characteristics under different anchor bolt-cable arrangement. The research indicated that separate anchor bolt-cable layout in different sections, anchor bolt and cable force stable equilibrium, coordinate with each other, at this time roadway surrounding rock of shallow and deep pretension distribution more reasonable, can play a role of bolt anchor cable synergistic action, and form the best pre-tension load-bearing structure, which is helpful to keep the stability of coal roadway.


2021 ◽  
Vol 31 (02) ◽  
pp. 2150018
Author(s):  
Wentao Huang ◽  
Chengcheng Cao ◽  
Dongping He

In this article, the complex dynamic behavior of a nonlinear aeroelastic airfoil model with cubic nonlinear pitching stiffness is investigated by applying a theoretical method and numerical simulation method. First, through calculating the Jacobian of the nonlinear system at equilibrium, we obtain necessary and sufficient conditions when this system has two classes of degenerated equilibria. They are described as: (1) one pair of purely imaginary roots and one pair of conjugate complex roots with negative real parts; (2) two pairs of purely imaginary roots under nonresonant conditions. Then, with the aid of center manifold and normal form theories, we not only derive the stability conditions of the initial and nonzero equilibria, but also get the explicit expressions of the critical bifurcation lines resulting in static bifurcation and Hopf bifurcation. Specifically, quasi-periodic motions on 2D and 3D tori are found in the neighborhoods of the initial and nonzero equilibria under certain parameter conditions. Finally, the numerical simulations performed by the fourth-order Runge–Kutta method provide a good agreement with the results of theoretical analysis.


2013 ◽  
Vol 860-863 ◽  
pp. 1416-1419
Author(s):  
Ri Guang Wei ◽  
Zhen Xiao Qu ◽  
Jian Qiang Gao

According to the structure and working principle of rotary air preheater,the heat transfer calculation model is set up with reasonable simplification. Combining with the design parameters of the rotary air preheater of a 400 t/h pulverized coal boiler unit ,the results of practical calculation show that the said thermodynamic calculation method not only has higher precision of calculation,but also can get the temperature distributions of the gas, air and heat surface in each cross-section of the rotary air preheater. The result of numerical simulation calculation tallies well with the original designed data. It can be used for the heat calculation both two-sectorial and three-sectorial air heater; it can be used for performance analysis of the regenerative air heater.


2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Fuxing Li ◽  
Hao Liu ◽  
Menglei Li ◽  
Jun Guo ◽  
Xinjian Lu ◽  
...  

Inertia force is an important factor for operation stability and stamping precision of high-speed punch; adjusting drive torque of high-speed punch can realize effective control of inertia force. In this paper, a kind of 600 KN multilink high-speed punch inertia force balancing mechanism was designed. The calculation model of ideal inertia force was proposed based on conservation of energy and numerical analysis method. In addition, the calculation model of ideal driving torque were analyzed, simplified, and corrected by using numerical calculation and simulation methods, which solved the problem of controlling inertia force from the perspective of driving torque and realized the stability strategy planning of high-speed multilink punch press. Finally, the proposed ideal driving torque calculation model was simulated and verified by ADAMAS and bottom-dead-point accuracy test was carried out.


2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Denghong Chen ◽  
Chao Li ◽  
Xinzhu Hua ◽  
Xiaoyu Lu ◽  
Yongqiang Yuan ◽  
...  

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.


Transport ◽  
2016 ◽  
Vol 33 (2) ◽  
pp. 335-343 ◽  
Author(s):  
Maciej Kozłowski

The construction of Personal Rapid Transit (PRT) vehicle made within the framework of Eco-Mobility project has been described in the present paper. Key features of the vehicles were identified – e.g. drive with three-phase linear motor with winding on the vehicle and fixed rotor in the road surface, contactless dynamic vehicle powering. Attention was paid to the difference in dynamic properties compared to rail vehicles, related to the lack of the so-called ‘centering mechanism’. A development of a nominal model for the analysis of vehicle drive properties was presented. Results of simulation studies were presented for a vehicle with running-drive system construction, planned for implementation in the city of Rzeszów (Poland). While discussing the problems of building a PRT system, there was a focus on the issue of determining power and traction of the vehicle. A methodology for determining the power and traction energy consumption of the vehicle was presented for assumed conditions of travel on road segments. Input values for the calculation of power are variables describing the curvature (or bends radii) of paths of movement between stops and the course of the current speed. Output values are total traction power or traction energy (where ‘traction’ refers to the power or mechanical work of drive forces). Three basic elements of traction power were isolated: the power of kinetic energy (for acceleration/delay of vehicle movement) basic (to offset the aerodynamic force of motion resistance at constant speed) and additional losses (to offset additional motion resistance forces operating in turns at constant speed). Due to the lack of vehicle prototypes with assumed structure, it was proposed that these components are determined via simulation. The presented results relate to the calculation of demand for power and energy for the planned test section. The scope of further work was indicated: determining the required traction characteristics of electric drive, selecting the best values for supercapacitor’s capacity in the drive system, determining the technical parameters of substation.


2021 ◽  
Vol 295 (2) ◽  
pp. 32-36
Author(s):  
A.E. Svyatoshenko ◽  
◽  

An engineering technique for calculating the tearing forces in the foundation bolts in the bases of centrally compressed columns is proposed. The calculation of the forces is based on the calculation of extra-centrally compressed rods, taking into account: the influence of the cross-section shape; the initial curvature of the neutral axis of the column; random eccentricity; nonlinear steel work. The calculation of the attachment forces (Nult and Mfic) of columns on the foundation edge is based on the method of practical calculations of centrally compressed elements using the stability coefficients at central compression φ (longitudinal bending coefficients), which are calculated depending on the flexibility l. The calculation of the attachment forces for rods with different reduced flexibility was performed by FEM in the FEMAP software package, as well as analytically using fictitious forces in centrally compressed rods. To calculate the tearing forces in the foundation bolts, a calculation model is made taking into account the contact interaction of the base and the reinforced concrete base. Graphs of the effect of the flexibility of the centrally compressed rod on the tearing force in the foundation bolts at the stage of exhaustion of the bearing capacity of the column when calculating its stability as an element of a continuous section under central compression are constructed.


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