石矿开采生态环境影响分析

本文以石灰石矿开发建设为例 ,在工程分析和环境影响因素识别基础上 ,构建了生态环境影响评价指标体系 ,并应用特尔菲法确定了自然和社会各生态因子的权重值 ,对石矿开发建设对周围生态环境的影响进行了量化分析评价 ,论证石矿开发建设的可行性。

林区石矿资源开采设计及森林资源保护

我国相当部分的资源蕴藏在林区,自然资源开采,不免要破坏原有植被。本文介绍了林区石矿开采的野外勘查、调绘、设计以及最有效的森林植被保护办法。

福州峨嵋山叶腊石矿床开发和利用

福州峨嵋山叶腊石矿是我国目前已知的最大叶腊石矿床,该矿床位于福州市城北东20Km处,属宦溪镇峨嵋村,地理座标东经119°20′,北纬26°15′,矿区有公路至福州(31Km),矿区标高331至636m,年平均气温20℃,年降雨量1600-2000mm。

Pump-lockage ore transportation system for deep sea flexible mining system

Based on characteristics of deep sea flexible mining system,a new pump-lockage ore transportation system was designed.According to Bernoulli equation and two-phase hydrodynamics theory,parameters of the new system were obtained and four ore transportation systems were analyzed.The results indicate that the pump head of 1 000 m mining system is 100-150 m and that of 5 000 m mining system is 660-750 m.In addition,based on similarity theory,a model of the new transportation system was made,which can simulate more than 5 000 m actual ore transportation system.So both theory and experiment prove that the new pump-lockage ore transportation system is an ideal design for deep sea flexible mining system.

Numerical Simulation of Independent Advance of Ore Breaking in the Non-pillar Sublevel Caving Method

The mechanism of stress generation and propagation by detonation loading in five separate independent advance of ore breaking patterns is discussed in the paper. An elastic numerical model was developed using AN- SYS/LS-DYNA 3D Nonlinear Dynamic Finite Element Software. In this package ANSYS is the preprocessor and LS-DYNA is the postprocessor. Numerical models in the paper to actual were l：10 and the element mesh was dissected in scanning mode utilizing the symmetry characteristics of the numerical model. Five different advance rates were studied. Parameters, such as the time required to maximum stress, the action time of the available stress, the maximum velocity of the nodes, the stress penetration time, the magnitude of the stress peak and the time duration for high stress were numerically simulated. The 2.2 m advance appeared optimum from an analysis of the simulation results. The results from numerical simulation have been validated by tests with physical models.

Orthogonal design and numerical simulation of room and pillar configurations in fractured stopes

Room and pillar sizes are key factors for safe mining and ore recovery in open-stope mining. To investigate the influence of room and pillar configurations on stope stability in highly fractured and weakened areas, an orthogonal design with two factors, three levels and nine runs was proposed, followed by three-dimensional numerical simulation using ANSYS and FLAC3~. Results show that surface settlement after excavation is concentrically ringed, and increases with the decrease of pillar width and distances to stope gobs. In the meantime, the ore-control fault at the ore-rock boundary and the fractured argillaceous dolomite with intercalated slate at the hanging wall deteriorate the roof settlement. Additionally, stope stability is challenged due to pillar rheological yield and stress concentration, and both are induced by redistribution of stress and plastic zones after mining. Following an objective function and a constraint function, room and pillar configuration with widths of 14 m and 16 m, respectively, is presented as the optimization for improving the ore recovery rate while maintaining a safe working environment.

Catastrophic destabilization of tunnel under rocks slipping in faultage

The model of catastrophic destabilization of tunnel under rock slipping in fault zone based on catastrophic theory and the potential function of fault movement were pre- sented.On the basis of the results above,through Taylor series expansion of the equation of equilibrium surface,its standard form was obtained.Analysis show that catastrophic destabilization of tunnel will occur only when stiffness ratio between elastic sector and strain weakening sector of soft rocks was larger than or equal to 1.On the other hand, sliding behavior and evolution path of fault were directly affected by exogenous process, and it was a major extraneous factor which leads to catastrophic destabilization of tunnel. In the condition of system catastrophe could be generated,if external forces vary from smaller to larger,firstly,fault sticks or creeps,and secondly,when external force equal to or larger than critical value,fault turns to slip suddenly.Inverse,if external forces vary from larger to smaller,fault smoothly slips firstly,when external force equal to or smaller than critical value,and fault turns to stick or creep suddenly.

Mechanism of energy limit equilibrium of rock burst in coal mine

With the increase of mining depth,the effect of rock burst on coal mining is becoming more and more obvious and the rock burst mechanism becomes more and more complicated.Scholars from many countries had put forward different mechanisms,but no one gave a reasonable explanation to the mechanism of rock burst.In this paper,based on the energy theories,we studied the energy limit equilibrium（ELE） of coal mine rock burst The coal seam with rock burst is divided into energy limit equilibrium zone（ELEZ）（A） and elastic zone（B）;we also determined the position where the rock burst occurs,including the roof and floor of coal seams;in addition,we derived the limit width of ELEZ and the mathematic relationship between the limit width and occurrence mechanism of rock burst：the energy difference function（EDF）,w（x） = w_j - w_p,because first-order derivative w＇（x）,is less than 0.So EDF is a monotonically decreasing function.The graph of the energy difference function was also determined, through which we analysed the occurrence mechanism of rock burst.

Effects of caving–mining ratio on the coal and waste rocks gangue flows and the amount of cyclically caved coal in fully mechanized mining of super-thick coal seams

Aimed at determining the appropriate caving–mining ratio for fully mechanized mining of 20 m thick coal seam, this research investigated the effects of caving–mining ratio on the flow fields of coal and waste rocks, amount of cyclically caved coal and top coal loss by means of numerical modeling. The research was based on the geological conditions of panel 8102 in Tashan coal mine. The results indicated the loose coal and waste rocks formed an elliptical zone around the drawpoint. The ellipse enlarged with decreasing caving–mining ratio. And its long axis inclined to the gob gradually became vertical and facilitating the caving and recovery of top coal. The top coal loss showed a cyclical variation; and the loss cycle was shortened with the decreasing in caving–mining ratio. Moreover, the mean squared error(MSE) of the amount of cyclically caved coal went up with increasing caving–mining ratio, indicating a growing imbalance of amount of cyclically caved coal, which could impede the coordinated mining and caving operations. Finally it was found that a caving–mining ratio of 1:2.51 should be reasonable for the conditions.

DISPATCHING REAL-TIME MODEL OF COMPUTER-CONTROLLED TRUCK

In order to recover ore as much as possible, a computer-controlled truck real-time dispatching model is conducted under the conditions of Qidashan lron Mine. It can not only acquire the optimization of shovel and truck operation, but also satisfy requirements of blending ores.The simulation results indicate the effectiveness of the model developed.

Rock bolt mechanical analysis and its application to engineering

Combined with the 3D FEM,end-anchored anchorage bolts were simulated by implicit anchorage bolt element.Implicit anchorage bolt elements hide in the elements of rock mass and extremely simplify the element subdivision.The calculated value of an- chorage bolt stress is larger than the measured one for the most time.we further analyzed the reciprocity of anchorage bolt and rock mass,and then deduced the analytical equa- tions of anchorage bolt stress and rock mass deformation under elasto-plastic state.The results indicate that it is essential to revise the anchorage bolts stress by using the formu- las deduced when rock mass is softened or significantly deformed.Finally,a case study indicates that the calculated results agree with those measured.Some helpful methods are offerd for more accurate simulation of the support effect and anchorage bolts real stress state.

Single-borehole measuring method for broken rock zone in gently inclined thin layer weakness structure

According to the structural characteristics of gently inclined thin layer rock mass in which lots of weak interlayer existed,the concept of gently inclined thin layer weakness structure was proposed.If single-borehole measuring method of the acoustic along the conventional arrangement mode was used in measuring the broken rock zone in this structure,the change of the relationship curves (Vp-L) between acoustic p-wave velocity (Vp) and borehole depth (L) would present the irregular feature due to the mechanical characteristics of layered rock mass and harmful effects of weak interlayers,and the scope of broken rock zone couldn't be defined quickly.Based on the analysis of the me- chanical characteristics of layered rock mass,the propagation rule of acoustic and distri- butions characteristics of plastic zone and slip zone in layered rock mass,new arrange- ment mode of acoustic measuring boreholes for broken rock zone in gently inclined thin layer weakness structure was proposed.Namely,the measuring boreholes in two sides were parallel to the strata,the measuring boreholes in the roof and floor perpendicular to the strata.Besides the controlling depth of the measuring boreholes in the scope of the large plastic zones or the large slip zones should be increased.Engineering example showed that new acoustic measuring boreholes arrangement mode had the better appli- cability and could determine the scope of the broken rock zone in the gently inclined thin layer weakness structure quickly.

Roadway deformation during riding mining in soft rock

"Riding mining" is a form of mining where the working face is located above the roadway and advances parallel to it.Riding mining in deep soft rock creates a particular set of problems in the roadway that include high stresses,large deformations,and support difficulties.Herein we describe a study of the rock deformation mechanism of a roadway as observed during riding mining in deep soft rock.Theoretical analysis,numerical simulations,and on site monitoring were used to examine this problem.The stress in the rock and the visco-elastic behavior of the rock are considered.Real time data,recorded over a period of 240 days,were taken from a 750 transportation roadway.Stress distributions in the rock surrounding the roadway were studied by comparing simulations to observations from the mine.The rock stress shows dynamic behavior as the working face advances.The pressure increases and then drops after peaking as the face advances.Both elastic and plastic deformation of the surrounding rock occurs.Plastic deformation provides a mechanism by which stress in the rock relaxes due to material flow.A way to rehabilitate the roadway is suggested that will help ensure mine safety.

The test research on partial relieving pressure for the entry in the deep mine under high stress and friable surrounding rock

Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.