Based on 3D modelling of typical tunnels in mines, the airflow distribution in a three-center arch-section tunnel is investigated and the influence of air velocity and cross section on airflow distribution in tunnels ...Based on 3D modelling of typical tunnels in mines, the airflow distribution in a three-center arch-section tunnel is investigated and the influence of air velocity and cross section on airflow distribution in tunnels is studied. The average velocity points were analyzed quantitatively. The results show that the airflow pattern is similar for the three-center arch section under different ventilation velocities and cross sectional areas. The shape of the tunnel cross section and wall are the critical factors influencing the airflow pattern. The average velocity points are mainly close to the tunnel wall. Characteristic equations are developed to describe the average velocity distribution, and provide a theoretical basis for accurately measuring the average velocity in mine tunnels.展开更多
The stability type and spatial distribution of surrounding rock are an important basis for the layout of hae tunuels and the selection of support patterns in a mine design. Based on a lot of investigations and testing...The stability type and spatial distribution of surrounding rock are an important basis for the layout of hae tunuels and the selection of support patterns in a mine design. Based on a lot of investigations and testing studies,a new engineering geological classification scheme of surrounding rock stability is put forward,which is easy to be applied,and reliable verified by examples. According to the classification system,the spatial divisions of surrounding rock stability can be delineated in an exploration progamme, providing relevant engineering geological informations for mine designers to prevent them from making the uurealistic tunnel layout and support展开更多
In order to establish an effective wireless communication system in an underground coal-mine environment, the propagation of radio waves through a rectangular-like mine tunnel was investigated by jointly, considering ...In order to establish an effective wireless communication system in an underground coal-mine environment, the propagation of radio waves through a rectangular-like mine tunnel was investigated by jointly, considering both the dielectric constant and the reflectance of a mine tunnel. By combining free space and modified waveguide propagation models, we propose a new hybrid propagation model based on ray tracing. Simulation results have shown the effectiveness of establishing a wireless Local Area Network (LAN) in this coal-mine environment. The results of this research will be very useful as a guide in the design and development of tunnel wireless LAN systems.展开更多
Stability level of tunnels that exist in an underground mine has a great influence on the safety,production and economic performance of mines.Ensuring of stability for soft-rock tunnels is an important task for deep c...Stability level of tunnels that exist in an underground mine has a great influence on the safety,production and economic performance of mines.Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress conditions.Using the available information on stratigraphy,geological structures,in situ stress measurements and geo-mechanical properties of intact rock and discontinuity interfaces,a three-dimensional numerical model was built by using 3DEC software to simulate the stress conditions around a tunnel located under high in situ stress conditions in a coal rock mass in China.Analyses were conducted for several tunnel shapes and rock support patterns.Results obtained for the distribution of failure zones,and stress and displacement felds around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions.展开更多
For the compressive stress-induced failure of tunnels at depth, rock fracturing process is often closely associated with the generation of surface parallel fractures in the initial stage, and shear failure is likely t...For the compressive stress-induced failure of tunnels at depth, rock fracturing process is often closely associated with the generation of surface parallel fractures in the initial stage, and shear failure is likely to occur in the final process during the formation of shear bands, breakouts or V-shaped notches close to the excavation boundaries. However, the perfectly elastoplastic, strain-softening and elasto-brittle-plastic models cannot reasonably describe the brittle failure of hard rock tunnels under high in-situ stress conditions. These approaches often underestimate the depth of failure and overestimate the lateral extent of failure near the excavation. Based on a practical case of the mine-by test tunnel at an underground research laboratory (URL) in Canada, the influence of rock mass dilation on the depth and extent of failure and deformation is investigated using a calibrated cohesion weakening and frictional strengthening (CWFS) model. It can be found that, when modeling brittle failure of rock masses, the calibrated CWFS model with a constant dilation angle can capture the depth and extent of stress-induced brittle failure in hard rocks at a low confinement if the stress path is correctly represented, as demonstrated by the failure shape observed in the tunnel. However, using a constant dilation angle cannot simulate the nonlinear deformation behavior near the excavation boundary accurately because the dependence of rock mass dilation on confinement and plastic shear strain is not considered. It is illustrated from the numerical simulations that the proposed plastic shear strain and confinement-dependent dilation angle model in combination with the calibrated CWFS model implemented in FLAC can reasonably reveal both rock mass failure and displacement distribution in vicinity of the excavation simultaneously. The simulation results are in good agreement with the field observations and displacement measurement data.展开更多
The return airway tunnel of bank 6 is an important tunnel for air return and auxiliary transportation.While under construction,the tunnel was seriously deformed, and the bottom was heavily squeezed.When completed,the ...The return airway tunnel of bank 6 is an important tunnel for air return and auxiliary transportation.While under construction,the tunnel was seriously deformed, and the bottom was heavily squeezed.When completed,the bottom was smoothed out several times and a lot of maintenance were done.But about half year later,the tunnel collapsed.To counter the problems mentioned above,we systematically expounded our ideas and designed for solving the problem of the sustenance of the return airway tunnel of section 6.展开更多
This paper proposes the cooling system type and cooling equipment type which are deep mine with high temperature during the construction,and presents auxiliary cooling measures making up duct temperature rise since co...This paper proposes the cooling system type and cooling equipment type which are deep mine with high temperature during the construction,and presents auxiliary cooling measures making up duct temperature rise since compression and heat transfer temperature rise. The cooling system designed against Zhaolou mine's ground temperature and weather conditions,with its sprinkler room handling an average temperature difference up to 19.5~23.8 ℃,and the average enthalpy difference could reach 48.4~60.7 kJ/kg. At the same time,it gets a series of basic data used for mine construction during the cooling system design and equipment selection according to the measured results; using the analysis software Matlab,it obtains the change relations between the temperature of sprinkler room and fan export supply air temperature,wind casing temperature rise and fan export supply air temperature,working face temperature and supply air temperature,used for the mine cooling which has the similar conditions.展开更多
In this paper,we first model the mining structure as a arched shape in terms of the tunnel geometry.Based on the regularly placement of nodes in that model,a set of deployment patterns for seamless coverage and k-conn...In this paper,we first model the mining structure as a arched shape in terms of the tunnel geometry.Based on the regularly placement of nodes in that model,a set of deployment patterns for seamless coverage and k-connectivity is proposed,i.e.1-and 2-connectivity.Further,we figure out the maximum horizontal distance of tangent plane to determine the placement of nodes for k-coverage(k=1,2).Besides,the mathematical relations between the communication radius and the sensing radius are derived,when the network keeps k-coverage(k=1,2) and k-connectivity(k=2,3) under certain regularity constrains for various patterns.Finally,we demonstrate the optimality of several approaches that we have proposed in the aspect of energy consumption and network lifetime.展开更多
基金supported by the Fundamental Research Funds for the Central Universities of China (No.17ZY001)
文摘Based on 3D modelling of typical tunnels in mines, the airflow distribution in a three-center arch-section tunnel is investigated and the influence of air velocity and cross section on airflow distribution in tunnels is studied. The average velocity points were analyzed quantitatively. The results show that the airflow pattern is similar for the three-center arch section under different ventilation velocities and cross sectional areas. The shape of the tunnel cross section and wall are the critical factors influencing the airflow pattern. The average velocity points are mainly close to the tunnel wall. Characteristic equations are developed to describe the average velocity distribution, and provide a theoretical basis for accurately measuring the average velocity in mine tunnels.
文摘The stability type and spatial distribution of surrounding rock are an important basis for the layout of hae tunuels and the selection of support patterns in a mine design. Based on a lot of investigations and testing studies,a new engineering geological classification scheme of surrounding rock stability is put forward,which is easy to be applied,and reliable verified by examples. According to the classification system,the spatial divisions of surrounding rock stability can be delineated in an exploration progamme, providing relevant engineering geological informations for mine designers to prevent them from making the uurealistic tunnel layout and support
基金supported by the National Natural Science Foundation of China (No.10974044)the Open Project of the Key Lab of the Technique of Electricity Transmission, Distribution and Conservation in Changzhou, China
文摘In order to establish an effective wireless communication system in an underground coal-mine environment, the propagation of radio waves through a rectangular-like mine tunnel was investigated by jointly, considering both the dielectric constant and the reflectance of a mine tunnel. By combining free space and modified waveguide propagation models, we propose a new hybrid propagation model based on ray tracing. Simulation results have shown the effectiveness of establishing a wireless Local Area Network (LAN) in this coal-mine environment. The results of this research will be very useful as a guide in the design and development of tunnel wireless LAN systems.
文摘Stability level of tunnels that exist in an underground mine has a great influence on the safety,production and economic performance of mines.Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress conditions.Using the available information on stratigraphy,geological structures,in situ stress measurements and geo-mechanical properties of intact rock and discontinuity interfaces,a three-dimensional numerical model was built by using 3DEC software to simulate the stress conditions around a tunnel located under high in situ stress conditions in a coal rock mass in China.Analyses were conducted for several tunnel shapes and rock support patterns.Results obtained for the distribution of failure zones,and stress and displacement felds around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions.
基金supported by China Scholarship Council and GRC/MIRARCO-Mining Innovation of Laurentian University, Canada
文摘For the compressive stress-induced failure of tunnels at depth, rock fracturing process is often closely associated with the generation of surface parallel fractures in the initial stage, and shear failure is likely to occur in the final process during the formation of shear bands, breakouts or V-shaped notches close to the excavation boundaries. However, the perfectly elastoplastic, strain-softening and elasto-brittle-plastic models cannot reasonably describe the brittle failure of hard rock tunnels under high in-situ stress conditions. These approaches often underestimate the depth of failure and overestimate the lateral extent of failure near the excavation. Based on a practical case of the mine-by test tunnel at an underground research laboratory (URL) in Canada, the influence of rock mass dilation on the depth and extent of failure and deformation is investigated using a calibrated cohesion weakening and frictional strengthening (CWFS) model. It can be found that, when modeling brittle failure of rock masses, the calibrated CWFS model with a constant dilation angle can capture the depth and extent of stress-induced brittle failure in hard rocks at a low confinement if the stress path is correctly represented, as demonstrated by the failure shape observed in the tunnel. However, using a constant dilation angle cannot simulate the nonlinear deformation behavior near the excavation boundary accurately because the dependence of rock mass dilation on confinement and plastic shear strain is not considered. It is illustrated from the numerical simulations that the proposed plastic shear strain and confinement-dependent dilation angle model in combination with the calibrated CWFS model implemented in FLAC can reasonably reveal both rock mass failure and displacement distribution in vicinity of the excavation simultaneously. The simulation results are in good agreement with the field observations and displacement measurement data.
文摘The return airway tunnel of bank 6 is an important tunnel for air return and auxiliary transportation.While under construction,the tunnel was seriously deformed, and the bottom was heavily squeezed.When completed,the bottom was smoothed out several times and a lot of maintenance were done.But about half year later,the tunnel collapsed.To counter the problems mentioned above,we systematically expounded our ideas and designed for solving the problem of the sustenance of the return airway tunnel of section 6.
文摘This paper proposes the cooling system type and cooling equipment type which are deep mine with high temperature during the construction,and presents auxiliary cooling measures making up duct temperature rise since compression and heat transfer temperature rise. The cooling system designed against Zhaolou mine's ground temperature and weather conditions,with its sprinkler room handling an average temperature difference up to 19.5~23.8 ℃,and the average enthalpy difference could reach 48.4~60.7 kJ/kg. At the same time,it gets a series of basic data used for mine construction during the cooling system design and equipment selection according to the measured results; using the analysis software Matlab,it obtains the change relations between the temperature of sprinkler room and fan export supply air temperature,wind casing temperature rise and fan export supply air temperature,working face temperature and supply air temperature,used for the mine cooling which has the similar conditions.
基金supported by the National Natural Science Foundation of China under Grant No.61562038
文摘In this paper,we first model the mining structure as a arched shape in terms of the tunnel geometry.Based on the regularly placement of nodes in that model,a set of deployment patterns for seamless coverage and k-connectivity is proposed,i.e.1-and 2-connectivity.Further,we figure out the maximum horizontal distance of tangent plane to determine the placement of nodes for k-coverage(k=1,2).Besides,the mathematical relations between the communication radius and the sensing radius are derived,when the network keeps k-coverage(k=1,2) and k-connectivity(k=2,3) under certain regularity constrains for various patterns.Finally,we demonstrate the optimality of several approaches that we have proposed in the aspect of energy consumption and network lifetime.