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1 英文文獻(xiàn) Roadheader applications in mining and tunneling industries H. Copur1, L. Ozdemir2, and J. Rostami3 1Graduate Student, 2 Director and Professor, and 3 Assistant Professor Earth Mechanics Institute, Colorado School of Mines, Golden, Colorado, 80401 ABSTRACT Roadheaders offer a unique capability and flexibility for the excavation of soft to medium strength rock formations, therefore, are widely used in underground mining and tunneling operations. A critical issue in successful roadheader application is the ability to develop accurate and reliable estimates of machine production capacity and the associated bit costs. This paper presents and discusses the recent work completed at the Earth Mechanics Institute of Colorado School of Mines on the use of historical data for use as a performance predictor model. The model is based on extensive field data collected from different roadheader operations in a wide variety of geologic formations. The paper also discusses the development of this database and the resultant empirical performance prediction equations derived to estimate roadheader cutting rates and bit consumption. INTRODUCTION The more widespread use of the mechanical excavation systems is a trend set by increasing pressure on the mining and civil construction industries to move away from the conventional drill and blast methods to improve productivity and reduce costs. The additional benefits of mechanical mining include significantly improved safety, reduced ground support requirements and fewer personnel. These advantages coupled with recent enhancements in machine performance and reliability have resulted in mechanical miners taking a larger share of the rock excavation market. Roadheaders are the most widely used underground partial-face excavation machines for soft to medium strength rocks, particularly for sedimentary rocks. They are used for both development and production in soft rock mining industry (i.e. main haulage drifts, roadways, cross-cuts, etc.) particularly in coal, industrial minerals and evaporitic rocks. In civil construction, they find extensive use for excavation of tunnels (railway, roadway, sewer, diversion tunnels, etc.) in soft 2 ground conditions, as well as for enlargement and rehabilitation of various underground structures. Their ability to excavate almost any profile opening also makes them very attractive to those mining and civil construction projects where various opening sizes and profiles need to be constructed. In addition to their high mobility and versatility, roadheaders are generally low capital cost systems compared to the most other mechanical excavators. Because of higher cutting power density due to a smaller cutting drum, they offer the capability to excavate rocks harder and more abrasive than their counterparts, such as the continuous miners and the borers. ROADHEADERS IN LAST 50 YEARS Roadheaders were first developed for mechanical excavation of coal in the early 50s. Today, their application areas have expanded beyond coal mining as a result of continual performance increases brought about by new technological developments and design improvements. The major improvements achieved in the last 50 years consist of steadily increased machine weight, size and cutterhead power, improved design of boom, muck pick up and loading system, more efficient cutterhead design, metallurgical developments in cutting bits, advances in hydraulic and electrical systems, and more widespread use of automation and remote control features. All these have led to drastic enhancements in machine cutting capabilities, system availability and the service life. Machine weights have reached up to 120 tons providing more stable and stiffer (less vibration, less maintenance) platforms from which higher thrust forces can be generated for attacking harder rock formations. . The cutterhead power has increased significantly, approaching 500 kW to allow for higher torque capacities. Modern machines have the ability to cut cross-sections over 100m2 from a stationary point. Computer aided cutterhead lacing design has developed to a stage to enable the design of optimal bit layout to achieve the maximum efficiency in the rock and geologic conditions to be encountered. The cutting bits have evolved from simple chisel to robust conical bits. The muck collection and transport systems have also undergone major improvements, increasing attainable production rates. The loading apron can now be manufactured as an extendible piece providing for more mobility and flexibility. The machines can be equipped with rock bolting and automatic dust suppression equipment to enhance the safety of personnel working at the heading. They can also be fitted with laser-guided alignment control 3 systems, computer profile controlling and remote control systems allowing for reduced operator sensitivity coupled with increased efficiency and productivity. Figure-1 shows a picture of a modern transverse type roadheader with telescopic boom and bolting system. Mobility, flexibility and the selective mining capability constitute some of the most important application advantages of roadheaders leading to cost effective operations. Mobility means easy relocation from one face to another to meet the daily development and production requirements of a mine. Flexibility allows for quick changes in operational conditions such as Figure-1: A Transverse Cutterhead Roadheader (Courtesy of Voest Alpine) different opening profiles (horse-shoe, rectangular, etc.), cross-sectional sizes, gradients (up to 20, sometimes 30 degrees), and the turning radius (can make an almost 90 degree turn). Selectivity refers to the ability to excavate different parts of a mixed face where the ore can be mined separately to reduce dilution and to minimize waste handling, both contributing to improved productivity. Since roadheaders are partial-face machines, the face is accessible, and therefore, cutters can be inspected and changed easily, and the roof support can be installed very close to the face. In addition to these, high production rates in favorable ground conditions, improved safety, reduced ground support and ventilation requirements, all resulting in reduced excavation costs are the other important advantages of roadheaders. The hard rock cutting ability of roadheaders is the most important limiting factor affecting their applications. This is mostly due to the high wear experienced by drag bits in hard, abrasive rocks. The present day, heavy-duty roadheaders can economically cut most rock formations up to 4 100 MPa (14,500 psi) uniaxial compressive strength (UCS) and rocks up to 160 MPa (23,000 psi) UCS if favorable jointing or bedding is present with low RQD numbers. Increasing frequency of joints or other rock weaknesses make the rock excavation easier as the machine simply pulls or rips out the blocks instead of cutting them. If the rock is very abrasive, or the pick consumption rate is more than 1-pick/m3, then roadheader excavation usually becomes uneconomical due to frequent bit changes coupled with increased machine vibrations and maintenance costs. A significant amount of effort has been placed over the years on increasing the ability of roadheaders to cut hard rock. Most of these efforts have focused on structural changes in the machines, such as increased weight, stiffer frames and more cutterhead power. Extensive field trials of these machines showed that the cutting tool is still the weakest point in hard rock excavation. Unless a drastic improvement is achieved in bit life, the true hard rock cutting is still beyond the realm of possibility with roadheaders. The Earth Mechanics Institute(EMI) of the Colorado School of Mines has been developing a new cutter technology, the Mini-Disc Cutter, to implement the hard rock cutting ability of disc cutters on roadheaders, as well as other types of mechanical excavators (Ozdemir et al, 1995). The full-scale laboratory tests with a standard transverse cutterhead showed that MiniDisc Cutters could increase the ability of the roadheaders for hard rock excavation while providing for lesser cutter change and maintenance stoppages. This new cutting technology holds great promise for application on roadheaders to extend their capability into economical excavation of hard rocks. In addition, using the mini-disc cutters, a drum miner concept has been developed by EMI for application to hard rock mine development. A picture of the drum miner during full-scale laboratory testing is shown in Figure-2. 5 Figure-2: Drum Miner Cutterhead FIELD PERFORMANCE DATABASE Performance prediction is an important factor for successful roadheader application. This deals generally with machine selection, production rate and bit cost estimation. Successful application of roadheader technology to any mining operation dictates that accurate and reliable estimates are developed for attainable production rates and the accompanying bit costs. In addition, it is of crucial importance that the bit design and cutterhead layout is optimized for the rock conditions to be encountered during excavation. Performance prediction encompasses the assessment of instantaneous cutting rates, bit consumption rates and machine utilization for different geological units. The instantaneous cutting rate (ICR) is the production rate during actual cutting time, (tons or m3 / cutting hour). Pick consumption rate refers to the number of picks changed per unit volume or weight of rock excavated, (picks / m3 or ton). Machine utilization is the percentage of time used for excavation during the project Table-I: Classification of the Information in the Database INFORMATION GROUP DETAILS General Information Type/purpose of excavation (roadway, railway, sewer, mining gallery, etc.), contractor, owner, consultant, location, starting and completion date, etc. Roadheader Information Manufacturer, condition of the roadheader (new, refurbished, direct reuse), specifications of roadheader, machine weight, cutterhead power and diameter, bit number and type, ancillary equipment (automatic profile control, water sprays, grippers, etc.) Technical and Operational Information Excavation length, depth, and gradients, dimensions of excavation profile, operator experience, cutting sequence at the face, daily and weekly mining hours, muck evacuation system, ground support system, etc. Rock Mass Information For Geological origin, number and character of geological zones, 6 Each Rock Zone hydrogeological conditions, rock mass classifications, RQD, bedding properties, joint set properties (orientation, spacing, roughness, filling, etc.) Intact Rock Information For Each Rock Zone Rock cuttability properties, uniaxial and tensile strength, elasticity modulus, surface hardness, texture (porosity, mineral / quartz content & grain sizes, microfractures, etc.), abrasivity properties, etc. Performance Records For Each Rock Zone Cutting rates, bit and holder consumption, roadheader utilization and availability, energy consumption, average and best advance rates (shiftly/daily/weekly/monthly), major obstructions to excavation operation, downtime analysis (roadheader related stoppages, backup system stoppages, ground and support stoppages, etc.) The Earth Mechanics Institute of the Colorado School of Mines jointly with the Mining Department of the Istanbul Technical University has established an extensive database related to the field performance of roadheaders with the objective of developing empirical models for accurate and reliable performance predictions. The database contains field data from numerous mining and civil construction projects worldwide and includes a variety of roadheaders and different geotechnical conditions. The empirical performance prediction methods are principally based on the past experience and the statistical interpretation of the previously recorded case histories. To obtain the required field data in an usable and meaningful format, a data collection sheet was prepared and sent to major contractors, owners, consultants, and roadheader manufacturers. In addition, data was gathered from available literature on roadheader performance and through actual visits to job sites. This data collection effort is continuing. The database includes six categories of information, as shown in Table-I. The geological parameters in the database consist generally of rock mass and intact rock properties. The most important and pertinent rock mass properties contained in the database include Rock Quality Designation (RQD), bedding thickness, strike and dip of joint sets and hydrological conditions. The intact rock properties are uniaxial compressive strength, tensile strength, quartz content, texture and abrasivity. The rock formations are divided into separate zones to minimize the 7 variations in the machine performance data to provide for more accurate analysis. This also simplifies the classification of the properties for each zone and the analysis of the field performance data. The major roadheader parameters included are the machine type (crawler mounted, shielded), machine weight, cutterhead type (axial, transverse), cutterhead power, cutterhead-lacing design, boom type (single, double, telescopic, articulated), and the ancillary equipment (i.e.grippers, automatic profiling, laser guidance, bit cooling and dust suppression by water jets, etc.). The operational parameters generally affect the performance of the excavator through machine utilization. The most important operational parameters include ground support, back up system (transportation, utility lines, power supply, surveying, etc.), ground treatment (water drainage, grouting, freezing, etc.), labor (availability and quality), and organization of the project (management, shift hours, material supply, etc.). CONCLUSIONS The evaluation and analysis of the data compiled in the roadheader field performance database has successfully yielded a set of equations which can be used to predict the instantaneous cutting rate (ICR) and the bit consumption rate(BCR) for roadheaders. A good relationship was found to exist between these two parameters and the machine power (P), weight (W) and the rock compressive strength (UCS). Equations were developed for these parameters as a function of P, W and UCS. These equations were found mainly applicable to soft rocks of evaporatic origin. The current analysis is being extended to include harder rocks with or without joints to make the equations more universal. In jointed rock, the RQD value will be utilized as a measure of rock mass characteristics from a roadheader cuttability viewpoint. It is believed that these efforts will lead to the formulation of an accurate roadheader performance prediction model which can be used in different rock types where the roadheaders are economically applicable. 8 中文譯文 掘進(jìn)機(jī)在采礦和隧道業(yè)中的應(yīng)用 摘要 掘進(jìn)機(jī)為方便的挖掘硬巖而提供了一個(gè)獨(dú)特的能力。因此,廣泛地被用于地下,采礦和隧道掘進(jìn)。在成功使用掘進(jìn)機(jī)方面的一個(gè)具有決定性的議題是提高機(jī)器生產(chǎn)率和降低采掘成本的可靠性分析。這篇文章提出并且討論科羅拉多學(xué)校地球力學(xué)研究會(huì)最近完成的工作對(duì)于挖掘在歷史上的使用數(shù)據(jù)當(dāng)作一個(gè)動(dòng)態(tài)的性能模型。這個(gè)模型 是從不同的掘進(jìn)機(jī)在各式各樣的地質(zhì)條件下工作為基礎(chǔ)來(lái)廣泛收集的數(shù)據(jù)。這篇文章也討論這一數(shù)據(jù)庫(kù)的發(fā)展和含量被源自估計(jì)掘進(jìn)機(jī)的截割率和截割頭能耗的預(yù)測(cè)為程序。 介紹 目前,機(jī)械挖掘系統(tǒng)廣大的使用在采礦和市政建造行業(yè)上,主要的趨勢(shì)是提高生產(chǎn)率和減低成本。這些主要的好處就是減少了土地的占有量;同時(shí),增強(qiáng)了工人的安全性。這些優(yōu)點(diǎn)主要取決于機(jī)器性能的大幅度提高,這些可靠性已經(jīng)造成采掘市場(chǎng)的擴(kuò)大,并且工人的水平得到了提高。 掘進(jìn)機(jī)是一種廣泛應(yīng)用在地下軟硬巖石的挖掘上的機(jī)器,特別是對(duì)于那些沉積巖。他們用在軟巖采礦行業(yè)的生產(chǎn)和 發(fā)展(也就是,巷道掘進(jìn)、支護(hù),打洞,等等)。特別是用在煤礦,礦山上。在市政建設(shè)中,經(jīng)常使用在較軟地面的管道開(kāi)掘(鐵路、公路、排水溝、導(dǎo)流管道等等)。連同于擴(kuò)大巷道或者地下結(jié)構(gòu)的復(fù)原。而且掘進(jìn)機(jī)的應(yīng)用能力非常廣泛,基本可以挖掘任何結(jié)構(gòu)和斷面的尺寸,不管巷道斷面有復(fù)雜,都能滿足人們的需求。因此,受到人們的一致歡迎。 除了那些高的機(jī)動(dòng)靈活性和適應(yīng)性之外,掘進(jìn)機(jī)另外一個(gè)最大的優(yōu)點(diǎn)就是成本低廉,經(jīng)濟(jì)性好。一般的掘進(jìn)機(jī)都有很大的功率,但卻是通過(guò)電磁方便的控制。因此,與其他機(jī)器相比,它能夠較好的掘進(jìn)硬巖和粉碎。例如連續(xù)開(kāi) 采和挖掘。 掘進(jìn)機(jī)近 50年的發(fā)展 掘進(jìn)機(jī)最初的使用是在上世紀(jì) 50年代煤礦的開(kāi)采中。今天,在科技高速發(fā)展的推動(dòng)下,人們?cè)O(shè)計(jì)的掘進(jìn)機(jī)性能和其他方面都有了很大的進(jìn)步,它們的應(yīng)用已經(jīng)遠(yuǎn)遠(yuǎn)超過(guò)了煤炭開(kāi)采的范圍。主要的改進(jìn)發(fā)生在最近這 50年。包括,機(jī)器的重9 量和尺寸比以往增大了很多,截割頭功率加大、支護(hù)桿,耙抓機(jī)構(gòu)和控制系統(tǒng)都得到了很大的改進(jìn)。高效率截割頭的設(shè)計(jì),高截割率截割齒的發(fā)展,高壓水射流輔助截割,電液一體化,較大地方使用自動(dòng)控制系統(tǒng)以及根據(jù)不同地質(zhì)條件間接控制。所以的這些都使機(jī)器的截割能力、工作效率、功率等都得到 了長(zhǎng)足的提高。 機(jī)器的重量已經(jīng)高達(dá) 120 噸左右,那樣接地比壓也得到提高。使機(jī)器更加穩(wěn)定和堅(jiān)固,那么,在截割較硬的巖石時(shí),面對(duì)大的沖擊機(jī)器仍然能保證較少的振動(dòng),維修率降低。目前,掘進(jìn)機(jī)的功率可達(dá)到 500KW 左右,使扭矩得到提高?,F(xiàn)在的機(jī)器截割斷面可達(dá)到 100m2。采用計(jì)算機(jī)輔助設(shè)計(jì),使截割頭的布置可達(dá)到一個(gè)最佳點(diǎn)切入巖石表面,那樣的話截割頭的工作效率達(dá)到最佳狀態(tài)。截齒已經(jīng)從簡(jiǎn)單的鉆發(fā)展到了錐形。煤巖裝載機(jī)構(gòu)和轉(zhuǎn)運(yùn)機(jī)構(gòu)也得到了很大的進(jìn)步,可達(dá)到生產(chǎn)率的要求。中間輸送機(jī)現(xiàn)在被制造成可伸縮式,使結(jié)構(gòu)簡(jiǎn)單化,裝運(yùn)方便 。前面裝有防護(hù)設(shè)施,使截割下來(lái)的巖石以及截割過(guò)程中產(chǎn)生的粉塵擋在外面,保證了操作人員的安全。掘進(jìn)機(jī)也能配備激光指導(dǎo)的對(duì)準(zhǔn)控制系統(tǒng),由計(jì)算機(jī)先分析出最佳的截割輪廓,如果按照此順序截割的話,截割效率和生產(chǎn)力都有成倍的提高。圖 1 展示的是一個(gè)橫軸式懸臂掘進(jìn)機(jī)以及耙抓機(jī)構(gòu)。 圖 -1 橫軸式掘進(jìn)機(jī) 普遍性、良好的控制性、和選擇性的采礦能力是掘進(jìn)機(jī)發(fā)展中需要大力改進(jìn)的因素,普遍性即指我們?cè)O(shè)計(jì)的掘進(jìn)機(jī)能夠適應(yīng)大多數(shù)礦山發(fā)展的需要。良好的控制性就是機(jī)器在過(guò)載時(shí)能夠自動(dòng)保護(hù),這樣不至于燒損機(jī)器。部分尺寸,擺角,(上擺角可達(dá) 20 度,下擺角可達(dá) 30 度)?;剞D(zhuǎn)半徑幾乎能達(dá)到 90 度。選擇性10 指的是在不同的工作環(huán)境下可以采取不同的截割功率挖掘礦石的能力,兩者能夠極大的改進(jìn)生產(chǎn)率。因?yàn)椋覀兯傅木蜻M(jìn)機(jī)是部分?jǐn)嗝婢蜻M(jìn)機(jī),可以接近斷面,因此,可以很容易的調(diào)整刀頭,并且頂板架能夠很方便地接近頂面。除了這些之外,高的生產(chǎn)率也取決于巖石的內(nèi)部特性。合理的改進(jìn)通風(fēng)設(shè)備,降低地表的壓
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