Drillability studies on the rotary blasthole drilling of lignite overburden series

ABSTRACT

This paper describes the results of drillability studies on rotary blasthole drillings for lignite overburden series at open pit lignite mines in Turkey. Field and laboratory studies are carried out at 96 different locations of 16 lignite mines to determine formation properties and to obtain drill performance data such as penetration rate, thrust, RPM. The obtained data analysed and the relation between some rock properties such as uniaxial compressive strength, cohesion, tensile strength, unit weight, impedance and penetration rate have been established. Among these rock properties, uniaxial compressive strength has been selected as a single parameter giving the highest correlation coefficient and to produce simple and practical relation. Finally thrust and RPM requirements are investigated and a chart based on uniaxial compressive strength is proposed to estimate thrust, RPM and corresponding penetration rate.     

Identification of indurated siltstone layers in advance of oil sands mining

Abstract

Indurated siltstone layers within both overburden and oil sands adversely affect rock handling productivity and maintenance at the Suncor mine. Drill performance monitoring and borehole geophysics have been used in the past to locate and characterize these hard layers at Suncor. The capabilities of both analog-and digital-based drill monitoring systems for the characterization of rock hardness are reviewed with reference to, Suncor and other mine studies. Particular reference is given to the alternative drilling-derived parameters to identify such zones and focuses on current studies at Suncor. This work relates to the development of diggability criteria and the subsequent ability to generate depth contour and thickness isopach plans for difficult bucket wheel and shovel digging conditions for mine planning.     

Application of rock mass weakening coefficient for stability assessment of slopes in heavily jointed rock mass

ABSTRACT

A geotechnical investigation in a large quarry was carried out in order 10 evaluate the rock mass strength parameters for designing slopes in jointed rock formations. The quantitative and qualitative parameters of rock miss discontinuities together with the laboratory strength parameters of intact rock were used for modifying rock mass weakening coefficient The RMR system and rock mass weakening coefficient in conjunction to Hoek and Brown empirical criterion was used to predict rock mass strength. It was found that the new rock mass classification system is consistent and cheaper alternative to the RMR rating system.     

Preliminary estimation of rock mass strength using diamond bit drilling operational parameters

In many mining engineering applications such as prospecting, development, production and grouting, diamond bit drilling is widely used due to high penetration rate, core recovery and its ability to drill with less deviation. It has been well known that the operational parameters of diamond bit drilling are closely related with rock mass strength properties. One of the most widely discussed subjects in drilling is the possibility of using diamond drill bit operational parameters for preliminary estimation of rock mass strength and deformability properties used in many mining engineering design projects. Once such rock properties are estimated, it will be possible to make tactical planning decisions as mining progresses. In this study two different techniques, multiple regression and adaptive neuro-fuzzy inference system (ANFIS) were used to develop the models for preliminary estimation of rock mass strength. The variables used in the models are widely known and recorded operational parameters of diamond bit drilling such as bit load, bit rotation and penetration rate. To develop the models, a database covering the rock properties and the machine operational parameters collected from seven different drill holes in Turkey was constructed. Results indicate that both regression and ANFIS-based models can successfully be used to predict the rock mass strength. Adaptive neuro-fuzzy inference model exhibits better performance according to statistical performance indicators. By means of the developed models it is possible to estimate the strength of rock mass during drilling operation, especially in weak and highly fractured rock masses. The estimated strength parameters can be related to further mining engineering applications such as the assessment of excavatability, blast design and even mine design studies.     

基于LabVIEW的液压凿岩机冲击频率采集系统

采用LabVIEW虚拟仪器技术成功提取某型液压凿岩机开孔冲击频率。为进一步根据冲击频率实现对液压凿岩机的智能控制、冲击性能分析、在线监测、故障诊断等工作提供参考。整个采集系统结构简单、性能稳定、信号保真度高,经过实践应用取得了良好效果。     

An investigation on the influence of depth of cut and blasting on shovel digging performance

ABSTRACT

This paper describes the results of performance monitoring of electrical shovels in terms of depth of cut and blast performance on diggability. A field research programme has been undertaken at four different rock units of surface coal mines, namely Yata?an fresh and weathered marl, Tinaz marl and conglomerate. A performance monitoring system has been developed and utilized for different type and size of power shovels. Three different depth of classes (< 0·4, 04–0·6, 0·6–0·8 meters for unblasted cases) are established and indicated on dipper of the shovel before excavation. Those depth of classes were tried with and/or without blasting. The digging difficulty of rock units in terms of power consumption has been determined before and after blasting. As it is expected, the power consumption and specific digging energy increase, as the rock unit becoming harder and stronger and depth of cut increases.     

Development of a preliminary rock mass classification scheme for near-surface excavation

ABSTRACT

In rock excavation work, the resistance of a rock mass depends partially on the mode of loading, shape of the loading instrument, rock moisture conditions and the orientations of the significant flaws relative to that of the applied force. Flaws or discontinuities in rocks may be cracks, bedding planes, weak grain boundaries and faults. Laboratory tests on rocks are often conducted on small cores of reasonably intact material. Generally, rocks decrease in strength with increase in sample size because the probability of the presence of large strength-controlling flaws increases with sample size. This is a plausible explanation for the disparity between laboratory and field specific energies often observed in rock excavation. Since the synergistic effects of discontinuity properties, scale of excavation and moisture condition can not be effectively evaluated using laboratory test results solely, it is necessary to use judgement along with such results in rating rock masses. Such a rating may involve the formulation of a single numerical index which must account for the significant properties, weighted to incorporate their relative importance. In this report, a preliminary classification system is formulated. It is called the Rock Trenchabiiity Classification (RTC). Consideration is given to rock material strength; rock brittleness; discontinuity spacing; orientations and linkage; and the scale of the excavation. Results of decades of investigations by many workers on various aspects of rock mass strength are taken into consideration.     

内燃凿岩机点火系统飞轮部件的结构改进

针对内燃凿岩机点火系统中飞轮部件充磁后磁场强度低且时有掉磁现象发生 ,导致火花塞跳火不强 ,凿岩机启动困难的缺陷 ,对飞轮部件进行了结构上的改进设计 ,使凿岩机的点火启动性能得到了明显的改善     

凸包型仿生耦合金刚石钻头模拟分析

研究发现仿生耦合钻头较普通钻头钻进时效提高很多。仿生耦合钻头一方面能使钻头唇面有较高的比压;另一方面能使钻头具有很好的冷却效果,因此在钻探工程中有很好的应用前景。应用数值模拟软件ansys,模拟分析了凸包型非光滑表面对金刚石钻头性能的影响。对比分析了4种不同非光滑度状况下,钻头在一定的钻压作用下在岩石表面产生滑动摩擦的过程。主要分析了该过程中岩层的等效应力、钻头底唇面的接触摩擦应力和接触压力的变化规律。研究发现,凸包型非光滑表面在一定程度上可以提高钻头的使用寿命和钻进效率。     

液压凿岩机回转性能测试系统的研究

在对液压凿岩机回转性能参数进行理论分析的基础上,依据国家标准的要求,建立了液压凿岩机回转性能测试系统,并对某型号液压凿岩机进行了回转性能测试试验,试验结果表明:本测试系统可完全满足液压凿岩机回转性能测试的需要,方便技术人员对液压凿岩机回转机构进行性能评价和提供改进依据,对提高液压凿岩技术具有重要意义。     

Slopes design in surface mines

ABSTRACT

Slopes design is part of surface mine planning Methods of slopes design are described in three parts. Overall slope angles are derived from geological, structural geomechanical, and water table data during the feasibility stage Variations of the safety factor to changes in slope angle are described in both cases of jointed rock mass and continuous rock mass Influences of slope curvature and underground workings upon stability are also mentioned Selection of basic slope types (geometry of benches) is then discussed. The problem of haul road insertion in the pit walls while saving slopes stability is tackled and a method proposed.     

Evaluating the effect of rock parameters on surface mine blasting by finite element analysis

ABSTRACT

The blasting process in surface mines involves extremely complex interactions. Utilizing Finite Element (FE) analysis, the affect of rock mass properties and discontinuity data can be fairly idealized and assessed. The purpose of this paper is to present the application of finite element methods to fragmentation due to blasting in surface mining operations. As a result, the prediction and extent of blasting will help the engineers engaged in surface mining and construction operations to use explosives efficiently.     

New trends in drilling and blasting technology

ABSTRACT

The mining industry is poised on the threshold of some exciting opportunities. It has been realized that the unit operations such as drilling, blasting, excavation, loading, hauling and crushing are interrelated variables in the total cost equation. The development, advancement and utilization of the innovative technologies are very important for the mining industry to be cost effective. In order to improve performance, the drilling and blasting industry is rapidly adopting technology in all forms. In the modem mines it is very common to encounter the latest forms of laser measurement technologies, global positioning systems (GPS), communication technology and computer systems. The developments in the areas of planning and design of blasts, drill monitoring, drillhole deviation, drill machine navigation systems and laser profiling systems have been discussed in this paper. The innovative practices in the areas of bulk loading of explosives, controlled blasting, explosive performance measurement and the evaluation of blast outcome and productivity have been outlined. The role to be played by the electronic detonators in the next millennium to improve blasting efficiency and mining economics has been described.     

Strength predictions for jointed rocks in confined and unconfined states

Most of the rational approaches to the design of structures on or in a rock mass are based on the strength response of the rock mass. Realizing this important aspect, the present investigation was undertaken to understand the strength response of jointed rocks. The objective was achieved by simulating joints in intact isotropic rock cores in the laboratory.Three materials, namely, plaster of Paris, Jamrani sandstone and Agra sandstone were selected. The intact specimens of these materials provided a wide range of compressive strength (σ_ci = 11.3−110MN/m²). A special technique was devised to develop joints varying in number and inclination. In all, about 250 uniaxial compressive strength (UCS) tests and 1300 triaxial tests on jointed and intact specimens of these materials were conducted. Based on this extensive experimentation, a joint factor J_f, has been evolved to account for the number of joints per metre length, inclination of the sliding joint and the shear strength along this joint. This factor is found to be uniquely related to the ratio of compressive strength of jointed rock to that of the intact rock irrespective of the type of rock. A strength criterion for jointed rocks is proposed and the parameters defining this criterion can be evolved simply by knowing the joint factor, compressive strength of intact rock and triaxial strength of intact specimens at two convenient confining pressures. The empirical relations developed have been verified with similar data for other jointed rocks and model materials.     

三山岛金矿西岭矿区深部岩体岩爆倾向性熵权法综合预测

为准确预测三山岛金矿西岭矿区深部岩体岩爆倾向性,本文综合考虑岩爆发生的内因和外因,选取岩石本身力学性质条件、围岩应力状态、围岩地质条件3个方面8项评价指标,通过地质钻孔岩芯岩爆倾向性试验,获得岩爆倾向性单指标评价结果,同时引入熵权-TOPSIS法建立岩爆多指标综合评价体系,对钻孔区域岩体进行了岩爆倾向性综合预测。研究表明:3个钻孔各测点深度岩体均具有一定岩爆倾向性,尤其是ZK88-18钻孔1 200m、1 500m和2 300m深度岩爆倾向性为强岩爆。对于深部完整性较好的岩层,在工程施工时需加强岩爆灾害的控制和管理工作。     

单向扰动加载触发煤体冲击破坏特性试验研究

运用MTS-C64. 106型压力机开展纯煤试件的单轴动静组合加载试验。结合PIC-2声发射卡和高速摄像机的监测结果,分析了单向扰动加载下煤体的力学、冲击性能、声发射特征、动态破坏特征、碎片分形特征。结果表明,扰动加载应变率增大,煤体强度呈对数增加;冲击性能增强;扰动能量输入速率、声发射振铃计数、撞击数呈现"缓增—急增—突增"的转变,试件破裂形式经历"剪切破裂—竖向劈裂—爆裂"的转变;碎片质量分维与动载应变率呈二次方关系,存在动载应变率极值使试件破坏程度达到最大,试验显示的应变率极值为2. 8×10~(-3)s~(-1)。     

预制非贯通单组裂隙岩石模型力学参数的实验研究

开展裂隙岩体破坏的力学特性的研究始终是岩体力学研究领域的重要课题,预制裂隙岩石模型是了解和掌握岩石破坏机理的一条重要途径,本文预置裂隙的水泥砂浆试块模拟节理发育的裂隙岩石,通过单轴压缩试验与剪切试验研究节理影响下的岩石力学参数的变化,并演示了裂隙的扩展贯通过程。研究表明：(1)岩体内部节理面的张开扩展延伸直至贯通从而引起非贯通节理岩体的破坏。(2)岩石模型的单轴抗压强度随着节理角度的增加逐渐下落,在节理角度达到45°时,试块的单轴抗压强度出现最小值,随后开始反向增大。(3)岩石模型单轴抗压强度与节理贯通率的关系满足一定的关系式,单轴抗压强度随着节理贯通率的增大而不断降低。(4)随着法向应力的增加,裂隙岩石模型的峰值剪应力也相应线性增大,当节理面存在充填物时会一定程度上会提高裂隙岩石的强度。这为裂隙岩石的破坏机理提供了重要的参考依据。     

基于响应面法的废石-细尾砂充填性能优化试验

为获得满足矿山采矿强度要求的废石-细尾砂充填最佳配比,首先根据混合骨料的堆积密实度和料浆浓度初探试验,初步获得配比范围;在此基础上利用响应面法建立了以废石-细尾砂充填体的3、7、28 d抗压强度为响应值的回归模型,揭示了骨料配比、浓度和灰砂比三因素对充填体强度的影响规律,并通过回归模型优选出充填最佳配比,进行半工业试验验证。结果表明,当充填体养护至3、7 d时,浓度和灰砂比两因素的交互作用影响显著;当充填体养护至28 d时,骨料配比与浓度的交互作用影响显著。当骨料配比1∶3、浓度82%、灰砂比1∶4时,废石-细尾砂充填性能完全满足矿山的充填需求,为废石-细尾砂混合骨料膏体充填性能优化提供了理论基础。     

Retrospektive zur Verwahrung des Kalischachtes Friedrich Franz Lübtheen – Sicherheitsbewertung dieser erstmalig im Kalibergbau angewandten Versatztechnologie nach 30 Jahren

In 1980, the shaft of the potash and rock salt mine Friedrich Franz in Lübtheen (district of Ludwigslust) was backfilled with a suspension of brown coal filter ashes. This technology for the backfilling of a solution-filled shaft including the complete shaft furniture was absolutely new at that time. In 2008 control core drillings were made, both in the backfilled shaft and the area close to the shaft. The obtained drill cores were tested for strength. Subsequent rock mechanical model calculations based on the analysis indicated that the surface is stable for at least 200 years.     

基于钻孔和截割的新型硬岩快速掘进工艺探讨

为了解决硐室工程领域硬岩快速掘进的问题,在“钻孔+液压冲击”的基础上,提出了“钻孔+振动+截割”的新型硬岩快速掘进工艺。在此基础上,分别对孔边距不变和总钻孔数不变情况下的关键钻孔直径进行了综合分析和对比,结果表明,钻孔直径140 mm时的截割头截割效率高,但总的节拍时间和效率并不明显占优。综合考虑液压凿岩机的价格、质量及对钻臂结构强度尺寸的影响,钻孔直径应在90~115 mm之间。