Mechanical analysis of roof stability under nonlinear compaction of solid backfill body

Based on the compaction characteristic test and the nonlinear compaction deformation characteristics of backfill material, this paper applies the theory of nonlinear elastic foundation of thin plate to establish a mechanical model of backfill body and roof in solid dense backfill coal mining. This study critically analyses the deflection equation of the roof by the energy method, derives the conditions of roof breakage and combined with concrete engineering practice analyses, determines roof movement regularity and stability in solid dense backfill mining. Analysis of the engineering practice of the 13,120 backfill panel of Pingmei 12# mine shows the theoretical maximum of roof convergence in backfill mining to be415 mm which is in significant agreement with the measured value. During the advancing process of solid backfill mining at the panel, the maximum tensile stress on the roof is less than its tensile strength which does not satisfy the conditions for roof breakage. Drilling results on the roof and ground pressure monitoring show that the integrity of roof is strong, which is consistent with the theoretical calculations described in this study. The results presented in the study provide a basis for further investigation into strata movement theory in solid dense backfill mining.     

Construction and stability of an extra-large section chamber in solid backfill mining

In solid backfill mining without gangue removal, the gangue is separated directly underground and back-filled into goaf. This necessitates the underground construction of an extra-large section chamber...     

木鱼石矿区景观生态规划设计

矿区景观是珍贵的社会文化资本,木鱼石矿区景观生态规划从以生态安全、资源循环、生物多样性、保护与再生的角度出发,在采矿区景观生态规划中注重对本土文化景观内涵的表现.文章以木鱼石景观生态构建与再生的规划理论为基础,因地制宜地设计了“一个中心、三带、三区”的整体框架,在景点设计中强调保存地段的景观特征,体现场地的历史变迁,重点强化场地功能,从而使其成为富有生命力的可持续生态景观.     

Failure mechanism of pump chambers and their optimized design in deep mining at Qishan Coal Mine

Pump chambers, normally used as dominant structures in mining engineering to insure the safety and production of un-derground coal mines, become generally deformed under conditions of deep mining. Given the geology and engineering condition of Qishan Coal Mine in Xuzhou, the failure characteristics of pump chambers at the -1000 m level show that the main cause can be attributed to the spatial effect induced by intersectional chambers, where one pump is constructed per well. We developed an opti-mized design of the pump room, in which the pump wells in the traditional design are integrated into one compounding well. We suggest that the new design can limit the spatial effect of intersectional chambers during construction given our relevant numerical simulation. The new design is able to simplify the structure of the pump chamber and reduce the amount of excavation required.Based on a bolt-mesh-anchor with a rigid gap coupling supporting technology, the stability of pump chamber can be improved greatly.     

Deformation control of asymmetric floor heave in a deep rock roadway:A case study

In order to control asymmetric floor heave in deep rock roadways and deformation around the surrounding rock mass after excavation, in this paper we discuss the failure mechanism and coupling control c...     

特殊条件下挡土墙的变形和强度控制设计

针对地下埋有管线及其场地范围有限等复杂环境,对不同部位采用不同的挡土墙截面形式和地基加固处理方式,通过设置跨越管线的地梁,从而保护管线不受上部荷载的影响;同时,两组管线两侧设置微型桩,从而保证了上部挡土墙的安全,减小了沉降,体现了挡土墙变形和强度的双控设计思想,并对挡土墙及其基础进行力学分析及稳定性验算,给出了设计方法.     

Prediction of rock-burst-threatened areas in an island coal face and its prevention:A case study

The island coal face arises in coal mines with the purpose of preventing gas explosion or maintaining the balance between mining and tunneling. However, its particular stress conditions in the surrounding rock may increase the difficulty of stress control in the coal face and in its mining roadways, especially when the coal seam, the roof, and the floor have rock-burst propensities. The high energy accumulated in the island coal face and in its roof and floor will intensify rock-burst propensity or even induce rock burst,which further result in great casualties and financial losses. Taking island coal face 2321 in Jinqiao coal mine as a case, we propose a method for the prediction of rock-burst-threatened areas in an island coal face with weak rock-burst propensity. Based on the analysis of the movement of the overlying roof and characteristics of stress distribution, this method combined numerical simulation with drilling bits to ensure the prediction accuracy. The effects of coal pillars with different widths on the mitigation of stress concentration in the coal face and on the prevention of rock burst are analyzed together with the mechanism behind. Finally, corresponding measures against the rock burst in the island coal face are proposed.     

Numerical simulation study on the relationship between mining heights and shield resistance in longwall panel

A numerical model based on a Continuum-based Distinct Element Method(CDEM) was used to carry out a dynamic simulation of the interaction between shield and rock strata movement in longwall mining. In Northern China, the Ordos coal field geological conditions and operational characteristics were used as a case example. The CDEM was constructed on Ordos coal field shield's operation characteristics and geological conditions. Numerical modelling was carried out to investigate the effects of different mining heights on the caving process, movement characteristics, equilibrium and stability conditions of overburden as the interaction between shield and surrounding rocks. With the numerical model, the internal factors for changes in shield resistance under different mining heights was found. The quantitative relationship between mining heights and shield resistance was also obtained by the numerical simulation.     

Numerical simulation study of the failure evolution process and failure mode of surrounding rock in deep soft rock roadways

Based on the safety coefficient method,which assigns rock failure criteria to calculate the rock mass unit,the safety coefficient contour of surrounding rock is plotted to judge the distribution form of the fractured zone in the roadway.This will provide the basis numerical simulation to calculate the surrounding rock fractured zone in a roadway.Using the single factor and multi-factor orthogonal test method,the evolution law of roadway surrounding rock displacements,plastic zone and stress distribution under different conditions is studied.It reveals the roadway surrounding rock burst evolution process,and obtains five kinds of failure modes in deep soft rock roadway.Using the fuzzy mathematics clustering analysis method,the deep soft surrounding rock failure model in Zhujixi mine can be classified and patterns recognized.Compared to the identification results and the results detected by geological radar of surrounding rock loose circle,the reliability of the results of the pattern recognition is verified and lays the foundations for the support design of deep soft rock roadways.     

Modeling boundary and edge effect of chloride diffusion for durability design of concrete structures exposed in marine environment

According to the Fick＇s second law of diffusion, six analytical solutions of chloride profile in concrete were studied and discussed with regard to different boundary and initial conditions. In those analytical solutions, the most prevailing error-function solution which is based on semi-infinite assumption is the simple one, but may under-estimate the chloride content in concrete and over-rate the life time prediction of concrete structures. The experimental results show that compared with other solutions, the chloride content in concrete predicted by error-function model is the minimum, and the calculation difference produced by different analytical models should not be ignored. The influence of models on chloride content prediction is more than other environment and material coefficients in some time. In order to get a more realistic prediction model, modification to error-function model is suggested based on analysis and calculation examples concerning the boundary and edge effect.     

历史空间特色凸现前提下的商业街界面景观问题探讨——以济南泉城路商业街中西段为例

商业街是城市景观特色体现的载体,街道界面是其景观特质重要的感知要素。历史空间内的商业街则更是敏感,不当的店面设计所形成的商业街二次界面会引起景观的杂乱,不利于街道景观的和谐与特色的凸现。本文以济南泉城路商业街中西段为例,剖析了不当的二次界面所带来的若干景观负面问题。提出了规划与建筑及其后期装饰设计工作的叠合延伸、加强城市管理部门建设前期的控制引导和建成后期的监督管理,以及提高全社会的城市文化意识三个解决问题的对策。     

3Ds Max与VRML在机械产品虚拟设计中的应用

虚拟设计是数字化建模与仿真技术的综合应用,在机械产品真实制造出来以前,通过数字化虚拟模型来模拟和预测产品在特定环境中的工作状况,通过运动和动力学仿真分析,发现设计中的缺陷,尽早修改设计方案。文章详细论述了利用3DsMax建立产品数字化虚拟模型和通过VRML编写脚本程序实现产品基于网络的交互式运动和动力仿真分析的方法。运用该方法成功地构建了基于网络的齿轮减速器动态仿真系统。