Complexity analysis of blast-induced vibrations in underground mining: A case study

Blasting in geological bodies is an industrial process acting in an environment characterized by high uncertainties (natural joints, faults, voids, abrupt structural changes), which are transposed into the process parameters (e.g. energetic transfer to rock mass, hole deviations, misfires, vibrations, fly-rock, etc.). The approach to this problem searching for the “optimum” result can be ineffective. The geological environment is marked out by too many uncertainties, to have an “optimum” suitable to different applications. Researching for “Robustness” in a blast design gives rise to much more efficiency. Robustness is the capability of the system to behave constantly under varying conditions, without leading to unexpected results. Since the geology varies from site to site, setting a robust method can grant better results in varying environments, lowering the costs and increasing benefits and safety. Complexity Analysis (C.A.) is an innovative approach to systems. C.A. allows analyzing the Complexity of the Blast System and the criticality of each variable (drilling, charging and initiation parameters). The lower is the complexity, the more robust is the system, and the lower is the possibility of unexpected results. The paper presents the results obtained thanks to the C.A. approach in an underground gypsum quarry (Italy), exploited by conventional rooms and pillars method by drilling and blasting. The application of C.A. led to a reliable solution to reduce the charge per delay, hence reducing the impact of ground vibration on the surrounding structures. The analysis of the correlation degree between the variables allowed recognizing empirical laws as well.     

Analysis of predictor equations for determining the blast-induced vibration in rock blasting

The paper proposes a new empirical correlation designed to complement the “site laws” currently used to evaluate the attenuation in the rock masses of vibrations induced by rock blasting. The formula contains a deformed exponential known as the K-exponential, which seems to well represent a large number of both natural and artificial phenomena ranging from astrophysics to quantum mechanics, with some extension in the field of economics and finance. Experimental validation of the formula was performed via the analysis of vibration data covering a number of case studies, which differed in terms of both operation and rock type. A total of 12 experimental cases were analysed and the proposed formulation exhibited a good performance in 11 of them. In particular, the proposed law, which was built using blast test data, produced very good approximations of the points representing the vibration measurements and would thus be useful in organising production blasts. However, the developed formula was found to work less well when a correlation obtained for a given site was applied to another presenting similar types of rocks and operations, and thus should not be employed in the absence of measurements from test data.     

新庄井田高岭石粘土岩中菱铁矿的研究

在永城矿区新庄井田二叠系下石盒子组内含有菱铁矿, 呈分散状、结核状分布在高岭石粘土岩中, 通过系统测试分析, 研究了菱铁矿在高岭石粘土岩层中的含量和特征, 对于高岭石粘土岩和菱铁矿的开发利用具有重要意义     

Coal rib response during bench mining: A case study

In 2016, room-and-pillar mining provided nearly 40% of underground coal production in the United States.Over the past decade, rib falls have resulted in 12 fatalities, representing 28% of the ground fall fatalities in U.S.underground coal mines.Nine of these 12 fatalities(75%) have occurred in room-andpillar mines.The objective of this research is to study the geomechanics of bench room-and-pillar mining and the associated response of high pillar ribs at overburden depths greater than 300 m.This paper provides a definition of the bench technique, the pillar response due to loading, observational data for a case history, a calibrated numerical model of the observed rib response, and application of this calibrated model to a second site.     

Long-term economic sensitivity analysis of light duty underground mining vehicles by power source

LHD's are expensive vehicles; therefore, it is important to accurately define the financial consequences associated with the investment of purchasing the mining equipment. This study concentrates on longterm incremental and sensitivity analysis to determine whether it is feasible to incorporate current battery technology into these machines. When revenue was taken into account, decreasing the amount of haulage in battery operated equipment by 5% or 200 kg per h amounts to a $4.0 × 10~4 loss of profit per year. On average it was found that using battery operated equipment generated $9.5 × 10~4 more in income annually, reducing the payback period from seven to two years to pay back the additional $1.0 × 10~5 investment of buying battery powered equipment over cheaper diesel equipment. Due to the estimated 5% increase in capital, it was observed that electric vehicles must possess a lifetime that is a minimum of one year longer than that of diesel equipment.     

A comprehensive geomechanical method for the assessment of rockburst hazards in underground mining

Rockburst hazard in mining industry all over the world is one of the most severe hazards. It is becoming increasingly common because of the ever-growing depths of mining operations accompanied by the increasing strength of rocks. One of the most difficult issues is to predict this hazard before the mining operations, whether geophysical investigations have been conducted or not. Polish experience in this field shows that in such cases an effective solution can be the geomechanical method. Therefore, extensive studies on rockburst hazard should focus on three main aspects:(1) rock mass and rock(and coal)predisposition to rockburst–laboratory tests and empirical analyses based on lithology,(2) identification of the potential places with stress and elastic energy concentration in the rock mass within the area planned for exploitation, and(3) the assessment of the impact of mining tremors on the surface. This preliminary geomechanical analysis assesses the propensity of the rock mass to dynamic breakage and provides quantitatively the level of rockburst hazard. The paper presents Polish experience in rockburst hazard assessment with the use of geomechanical method, as well as some solutions and examples of such analyses.     

Large-scale destress blasting for seismicity control in hard rock mines: A case study

Destress blasting is a rockburst control technique where highly stressed rock is blasted to reduce the local stress and stiffness of the rock, thereby reducing its burst proneness. The technique is commonly practiced in deep hard rock mines in burst prone developments, as well as in sill or crown pillars which become burst-prone as the orebody is extracted. Large-scale destressing is a variant of destress blasting where panels are created parallel to the orebody strike with a longhole, fanning blast pattern from cross cut drifts situated in the host rock. The aim of panel destressing is to reduce the stress concentration in the ore blocks or pillars to be mined. This paper focuses on the large-scale destress blasting program conducted at Vale's Copper Cliff Mine(CCM) in Ontario, Canada. The merits of panel destressing are examined through field measurements of mining induced stress changes in the pillar. The destressing mechanism is simulated with a rock fragmentation factor(a) and stress reduction/dissipation factor(b). A 3D model is built and validated with measured induced stress changes. It is shown that the best correlation between the numerical model and field measurements is obtained when the combination of a and b indicates that the blast causes high fragmentation(a = 0.05) and high stress release(b = 0.95) in the destress panel. It is demonstrated that the burst proneness of the ore blocks in the panel stress shadow is reduced in terms of the brittle shear ratio(BSR) and the burst potential index(BPI).     

矿井水文地质类型划分的Fisher判别分析法——以开滦矿区为例

针对开滦矿区11个生产矿井水文地质类型重新划分问题,根据新出台的《煤矿防治水规定》有关矿井水文地质类型划分的标准要求,采用Fisher判别分析法,选取6项考核指标,建立线性判别函数,进行矿井水文地质类型重新划分.结果表明:11个生产矿井中有1个为极复杂型、5个为复杂型、5个为中等型,Fisher判别分析法划分的矿井水文地质类型与实际划分结果相符;Fisher判别分析过程中遇到了"极复杂型"样本数量太少,仅为1个的情况,造成交叉验证的结果正确率为72.7%,剔除后正确率就提升为100%;Fisher判别分析法对有代表性的样品进行交叉验证的正确率为100%,说明该方法可以科学地判断矿井水文地质类型.     

Optimized design of drilling and blasting operations in open pit mines under technical and economic uncertainties by system dynamic modelling

Drilling and blasting are the two most significant operations in open pit mines that play a crucial role in downstream stages. While previous research has focused on optimizing these operations as two separate parts or merely in a specific parameter, this paper proposes a system dynamic model(SDM) for drilling and blasting operations as an interactive system. In addition, some technical and economic uncertainties such as rock density, uniaxial compressive strength, bit life and operating costs are considered in this system to evaluate the different optimization results. For this purpose, Vensim simulation software is utilized as a powerful dynamic tool for both modelling and optimizing under deterministic and uncertain conditions. It is concluded that an integrated optimization as opposed to the deterministic approach can be efficiently achieved. This however is dependent on the parameters that are considered as uncertainties.     

Water protection in the western semiarid coal mining regions of China: A case study

The coal industry in China has been moving from the semiarid eastern to the drier western regions since the beginning of this century. Water protection is of the utmost concern for coal mining in these regions. Lu’an, as one of the state coal mining bases in China, has been seeing increasingly heavier pressure for the protection of water resources. This article considers Lu’an as an example and describes the ways these concerns may be alleviated. High mine-water utilization rates have effectively reduced wasting of water and, consequently, have reduced water demand. Using the top layers of the Ordavician as aquifuge barriers can prevent floor karst water inrush into the longwall face and can protect the regional Ordovician karst water resources at the same time. The strength of the overlying Quaternary clay can protect against roof collapse and has successfully preserved the Quaternary porous water resource.     

Heavy rockbursts due to longwall mining near protective pillars:A case study

Rockburst represents a very dangerous phenomenon in deep underground mining in unfavourable conditions such as great depth, high horizontal stress, proximity of important tectonic structures, and unmined pillars. The case study describes a recorded heavy rockburst in the Czech part of the Upper Silesian Coal Basin, which occurred during longwall mining near the protective pillar. The artificial dividing of geological blocks and creation of mining protective pillars(shaft pillars, crosscut pillars etc.) is a dangerous task in light of rockbursts occurring mainly due to overstressing of remaining pillars. A simple model of this situation is presented. Natural and mining conditions are analysed and presented in detail as well as registered seismicity during longwall mining in the area. Recorded rockbursts in the area of interest are described and their causes discussed. Many rockbursts near protective pillars were recorded in this mining region. Methodical instructions for rockburst prevention in proximity of protective pillars as well as for gates driving were devised based on the evaluation of rockburst causes. The paper presents these principles for prevention.     

基于水资源分异特征及其敏感性分析的生态功能区划——以哈尔滨市辖区优控单元为例

为提高松花江流域哈尔滨市辖区优先控制单元的水资源科学管理能力,采用SWAT模型对水资源时空分异特征进行模拟,结果表明:研究区内水资源时空分布不均匀,年内汛期与枯水期径流占比分别为56%和16.1%,径流年际变化范围为725～2 872 m~3/s,多年平均径流量为1 320 m~3/s,研究区月降水量在6月和8月呈现显著的上升趋势.水资源空间分布结果表明,丰/平/枯年份各亚流域水资源分布情况不同,水资源贡献较大的区域主要集中在亚流域20和23,其中亚流域20在丰、平、枯年份对径流的贡献率均最大,分别为10.64%,8.2%和11.31%.根据亚流域水资源敏感性特征,将哈尔滨优控单元进一步细化为8个四级生态功能分区,并结合功能分区目标给出水资源管理与利用方案,籍以指导流域水资源管理与科学利用.     

Pushover analysis of underground structures: Method and application

Pushover analysis is common because of its conceptual simplicity and computational attractiveness in computing seismic demand. Considering that traditional pushover analysis is restricted in underground structures due to the stark differences in the seismic response characteristics of surface structures, this paper proposes a pushover analysis method for underground structures and its application in seismic damage assessment. First, three types of force distribution are presented based on ground response analysis. Next, the target displacements and analysis models are established according to force-based and performance-based design. Then, the pushover analysis procedure for underground structures is described. Next, the applicability of pushover analysis to underground structures is verified by comparing the responses of a Chongwenmen subway station determined by the proposed procedure and by nonlinear response history analysis. In addition, two other points are made: that the inverted triangular distribution of effective earthquake acceleration is more practical than the other two distributions, and that performance-based design is more effective than force-based design. Finally, a cyclic reversal loading pattern based on one cycle of reversal loads as an earthquake event is presented and applied to the seismic damage assessment of underground structures. The results show that the proposed pushover analysis can be effectively applied to the seismic design and damage assessment of underground structures.     

Sensing for advancing mining automation capability: A review of underground automation technology development

This paper highlights the role of automation technologies for improving the safety, productivity, and environmental sustainability of underground coal mining processes. This is accomplished by reviewing the impact that the introduction of automation technology has made through the longwall shearer automation research program of Longwall Automation Steering Committee (LASC). This result has been achieved through close integration of sensing, processing, and control technologies into the longwall mining process. Key to the success of the automation solution has been the development of new sensing methods to accurately measure the location of longwall equipment and the spatial configuration of coal seam geology. The relevance of system interoperability and open communications standards for facilitating effective automation is also discussed. Importantly, the insights gained through the longwall automation development process are now leading to new technology transfer activity to benefit other underground mining processes.     

科学计量学视野下的《傲慢与偏见》研究——一个案例性的探究

选择1998—2009年中国学术期刊网收录的关于《傲慢与偏见》研究的458篇论文,尝试运用词频、共词、社会网络分析及信息可视化等科学计量学方法,对国内十多年来《傲慢与偏见》的研究现状、研究主题、研究力量分布、研究水平及整体概况和特征等进行了计量分析和可视化识别,对国内该文学研究领域的各方面状况做了一个比较客观而系统的描绘与判断,发现了一些用其他研究方法难以发现的问题。同时,作为一种新的研究方法的探索性尝试,初步探讨了该方法在文学研究领域使用的可能性和前景,以及应注意的若干问题。     

山丘区地下水资源控制开采的分析与评价

地下水资源储量对某一地区是一定的，亦是有限的。北方地区由于地表水资源本不丰富，地下水资源就更为珍贵。尤其是山丘区其地下水资源因含水层极薄、储量非常有限，若不遵循一套科学的开发利用规划而无序开采，所造成的一系列环境恶化、甚至给人类带来灾难性的报复，将是无法估量的。以黑龙江省鸡西市为例加以阐述。     

A review of laser scanning for geological and geotechnical applications in underground mining

Laser scanning can provide timely assessments of mine sites despite adverse challenges in the operational environment. Although there are several published articles on laser scanning, there is a need to review them in the context of underground mining applications. To this end, a holistic review of laser scanning is presented including progress in 3D scanning systems, data capture/processing techniques and primary applications in underground mines. Laser scanning technology has advanced signific...     

开采沉陷预计分析系统研究

介绍了在MapInfo 6.0平台上用MapBasic和Visual C++ 6.0语言进行二次开发设计出的开采沉陷预计分析系统。主要介绍了系统的开发平台、运行环境、系统的结构及其功能,以及开发系统所涉及的关键技术。Visual C++ 6.0中的ODBC技术提供的Access数据库将其与MapInfo 6.0有机结合起来,对开采沉陷预计的相关数据进行操作和分析,从而预计出地表移动变形的范围、程度和趋势等,实现了开采沉陷预计分析的可视化。     

Application of ventilation simulation to spontaneous combustion control in underground coal mine: A case study from Bulianta colliery

Spontaneous combustion of residual coal in longwall goaf is a long standing hazard. Airflow leakage into goaf is a major driver to the hazard and this issue deteriorates where longwalls are operating in multiple seams and shallow covers because mining-induced cracks are very likely to draw fresh airflow into goaf due to presence of pressure differential between longwall face and surface. To study the problem more critically, a ventilation simulation package ‘‘Ventsim" is used to conduct a case study from Bulianta colliery. It was found that isolating and pressurizing active longwall panel can mitigate the problem and the pressure differential can be adjusted by varying performance of auxiliary fan and resistance of ventilation regulator. A booster ventilation system can also mitigate the problem by adjusting fan duties. Ventilation simulation is a powerful tool to study spontaneous combustion control in underground coal mine.     

低周波装置在煤矿电力系统中的应用分析

本文结合晋城煤业集团公司电力系统 ,分析了电力系统在低周波下运行的危害、防止方法 ,针对安装使用ZPJH装置在晋煤集团电力系统的安全运行中存在的问题 ,提出了解决对策