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英文原文Quantifying the performance of resin anchored rock bolts in the Australian underground hard rock mining industry， Western Australian School of Mines, PMB 22, Kalgoorlie 6430, Australia Barrick Australia, P.O. Box 1662, Kalgoorlie 6433, Australia1. IntroductionThe purpose of rock support and reinforcement is to ensure excavations remain safe and open for their intended life span. The effectiveness of a reinforcement strategy is important for two main reasons: these being safety to personnel and equipment, and achievement of the most economical access to extract ore. For a particular rock mass, a stabilization scheme capable of matching the expected behaviour is selected based on an assessment of the likely failure modes predicted from the interaction of an excavation (geometry and purposes), the network of geological discontinuities, weathering and the loading conditions from stress and blast damage 14.In most underground mines, the primary form of excavation stabilization is provided by a pattern of rock bolts installed within the rock mass. This is complemented with the use of passive support, such as that provided by mesh or shotcrete, in order to provide surface restraint at the exposed excavation boundaries.The reinforcement controls the overall excavation stability through keying, arching or composite beam reinforcing actions 5, while the mesh and/or shotcrete supports the small loose pieces of rock that may detach between the rock bolt plates 6,7.In general, a stabilization scheme cannot be selected without consideration of the ground support drilling equipment available at a particular mine site. A modern, optimal strategy would consist of mechanized installation of reinforcement and support in a single pass in order to increase productivity and reduce exposure of personnel and equipment during installation.2. Mechanized resin anchored bolt installationOver the last decade or so, jumbo-installed, 45mm diameter galvanized and black steel friction bolt stabilizers have become the preferred form of reinforcement in underground hard rock mining in Australia 8,9. This has been mainly driven by a desire to achieve fast development rates and low costs in order to allow the extraction of low-grade orebodies. In more recent years, as the mining operations are getting deeper and the rock masses are becoming highly stressed, other reinforcement schemes such as fully encapsulated resin anchored bars are being considered as an alternative to friction bolts for longterm reinforcement 1013.The typical bolts being used in the underground hard rock mines have been modified from the bolts used in the coal mining industry. The modifications have been necessary due to the need to drill larger hole diameters with the type of equipment used in the hard rock metaliferous mines. The modification is mainly in the form of paddles or the use of a spring welded on to the end section of the bolts. Fig. 1 shows the anchor sections for a 24mm Posimix bolt with spring arrangement and a 27mm Secura bolt showing a paddle arrangement. The Posimix wire is 3mm in diameter and has a length of 500 mm. The paddle width is 29.2mm and they have been sheared into the end of the bolt for the purpose of mixing resin.Fig. 1. Posimix and Secura bolts showing spring and paddle mixing arrangements, respectively.Nevertheless, the introduction of mechanized resin anchored bolting using jumbos has been difficult to implement economically due to the high cost of resin transport and storage: this requires the use of refrigerated trucks and surface and underground storage facilities. Other problems include speed of installation of bolt installation, including ability to install mesh on a single pass, poor matching of bolt diameter to jumbo-drilled hole diameters, as well as operator skills.3. The load transfer conceptA fully encapsulated rock bolt is classified as continuous mechanically coupled in terms of the basic mechanisms of load transfer between the reinforcing elements and a rock mass 14. A continuous mechanically coupled (CMC) reinforcing element relies on a fixing agent, usually a cement or resin based grout, which fills the annulus between the element and the borehole wall. The main function of the grout is to provide a mechanism for load transfer between the rock mass and the reinforcing element.The load transfer concept is critical to understand how fully encapsulated bolts stabilize an excavation. Windsor and Thompson 15, explain the concept by means of the three basic individual components, listed as follows (see Fig. 2):1. Rock movement at the exposed excavation boundary, which causes load transfer from an unstable region (wedge or slab) to a reinforcing element.2. Transfer of load via the reinforcement element from the unstable portion to a stable interior region within the rock mass.3. Transfer of the reinforcing element load to the rock mass in the stable zone.Fig. 2. The load transfer concept for fully encapsulated reinforcement elements 3.Failure of a block being supported can occur during anyone of the three separate components of load transfer due to rock mass deterioration within the unstable zone, insufficient steel capacity (rupture of the reinforcement element) or inadequate load transfer (slippage).The reinforcing elements are usually manufactured with variable cross-sectional shapes in order to increase the element to grout load transfer. A mechanical key is effectively created by the geometrical interference between the element and the grout along the entire reinforcement length. The element is defined as continuously coupled to the rock mass by way of interlock with the grouting agent.In the case of resin grouted bolts, experience from in situ pull testing shows that high transfer loads can be achieved over short embedment lengths. However, cartridge resin systems may suffer from either underspining or overspining. Underspining results in poor mixing and low resin grout strength, often at the critical anchor end of the hole. In some cases the resin will never set. Overspining during installation can result in shearing of the partially cured resin. This results in reduced bonded area and lower load transfer. In addition, gloving of the bolts by the plastic packaging may occur; this may completely eliminate load transfer along the bolt axis 16.4. Conventional quality controlThe performance and ultimate capacity of a reinforcement scheme can be affected by sub-standard installation practices. However, in CMC schemes, faulty installations are difficult to detect, given that the only visible part of an installed element is the plate, nut and a short length of the bolt indicating the orientation of installation with respect to an excavation wall. Thus, for a fully encapsulated resin grouted rebar, it is very difficult to determine the bonded length (bolt encapsulation) along the entire axis of the bolt. In addition, because the full bolt capacity may be mobilized with very short embedment lengths of good quality resin, pull testing of exposed collar lengths within a fully grouted element is almost meaningless. Pull testing as suggested by the International Society of Rock Mechanics 17 only provides an indication of resin effectiveness at the collar or at the first (unknown) location along the bolt axis where the resin is effectively working. It only provides a definite indication of poor installation in cases where the entire length of resin encapsulated reinforcement fails well below its designed capacity.Short-length resin encapsulation tests cannot be used for quality control, as they do not provide a measure of resin mixinghence, load transferfound on a full scale test 18. Conventional pull testing programs for quality control can only be meaningfully applied to point anchored or friction bolts. In addition, non-destructive ultrasonic testing methods 19 are either still in development or have not been widely used in Australia.5. Bolt overcoringThe development of a purpose-built drill rig capable of overcoring reinforcement elements within a production mining environment was initiated due to an urgent and overwhelming need to examine the entire length of fully encapsulated rock bolts in situ.Research at the Western Australia School of Mines (WASM) has resulted on a versatile overcoring system capable of drilling at any orientation (3601) and overcoring reinforcement lengths up to 3m. Overcoring of in situ bolts can be undertaken in the walls and backs to a collar height of 57 m. The WASM rig is shown drilling in Fig. 3.Fig. 3. WASM bolt overcoring operations.Careful drilling and suitable penetration rates are chosen, so that the recovered 140mm diameter core undergoes minimal disturbance even in very poor rock masses that have been reinforced using friction stabilizers (see Fig. 4). This allows not only the recovery of the element, but also provides a clear view of the surrounding rock mass and a better understanding of the rock bolt system/rock mass interaction.Fig. 4. Full recovery from overcored friction bolts in very poor rock masses.Bolt overcoring provides a range of information including location and frequency of geological discontinuities, overall rock mass conditions, bolt encapsulation, load transfer along the bolt axis and corrosion effects 20.Overcoring in broken ground or shear zones shows that very little resin migration occurs in jumbo-installed resin bolts. The resin simply fills the annulus between the bolt and the borehole. Because of its viscosity the resin is unable to penetrate the rock mass fissures and voids (see Fig. 5). In comparison, significant cement migration has been observed during overcoring of cement grouted bolts in poor ground conditions (see Fig. 6). The degree of rock mass interlocking using cement grout is superior compared to that achieved by resin grouting or friction stabilizers. Interlocking around an underground excavation has been suggested as an important mechanism to allow the rock mass to be self-supporting 3.Overcoring also provides information on hole overdrilling, which is likely to result in the bolts not being fully encapsulated within the collar regions due to the resin migrating into the over-drilled portion at the toe of the borehole (see Fig. 7).6. Laboratory testingThe WASM has developed a laboratory procedure to assess the performance in terms of encapsulation quality and load transfer of the recovered overcored bolts. Following overcoring, the samples are transported to WASM where each sample is geologically mapped and appropriate sections are cut from the sample to test the force-displacement characteristics. In general, a forcedisplacement curve provides an indication of stiffness, peak and residual forces as well as the displacement capacity. The results can be used as a relative measure of loadtransfer (installation quality and bolt effectiveness) along the bolt axis.Fig. 5. Negligible resin migration within large shear zones.Fig. 6. Interlocking of a broken rock mass by the cement grouting process.Fig. 7. Poor encapsulation at the collar region and evidence of hole overdrilling.The typical embedment length used for pull tests at WASM is 300 mm. However, the total sample length required for a typical pull test is a minimum of 700800 mm; thus, for a typical 2.4-m-long bolt it is possible to select up to three samples for pull testing. This allows the variability of encapsulation and relative load transfer to be established for the bolt collar and toe regions. A typical pull test will have a 300mm rock-element portion and a 400500mm length of steel exposed. Some of the rock is removed leaving a section of the element partly exposed (see Fig. 8). The remaining rock/element section is then confined in a metal jacket to simulate the radial confinement provided by the rock mass in situ. The exposed section of the element is then pulled. A plate is used to restrict the movement of the confined 300-mm-long portion of bolt/rock (see Fig. 9).Fig. 8. Prepared short sections of overcored bolts prior to testing.Fig. 9. Typical pull test arrangement for a 300mm embedment length.The force required to pull the elements through the rock and its displacement is digitally recorded. The elements are then inspected and photographed following testing. The results show that in most cases where the load transfer was effective, failures of the resin bolts occurred at the resin/ rock interface. The frictional resistance was mobilized by shearing of the resin irregularities at the resin/rock interface. However, when the resin encapsulation was poor, failure at the bolt/resin interface was experienced. This implies poor installation practices leading to unsatisfactory mixing of the resin (see Fig. 10).Fig. 10. Example of (a) effective load transfer and (b) excessive gloving by the resin cartridge.Gloving is a term used to describe the encasing or partial encasing of the bolt by the plastic packaging. Gloving has been recognized for many years, initially within the coal mining industry, and has been reported by a number of people including Pettibone 21. The explanation for the occurrence of gloving has been put down to design characteristics of the bolt and resin cartridge, installation quality, hole size and drilling equipment, and handling and storage methods. Another phenomenon detected by overcoring is sideway displacement of the resin by the rockbolts as shown in Fig.11. This may occur when the bolt diameter is significantly small compared with the hole size.Fig. 11. Example of sideway resin displacement.7. Typical forcedisplacement resultsTable 1 shows a series of overcoring results where samples of equal embedment length were selected along a particular bolt axis within the collar (Sample A) and anchor (Sample B) regions, respectively. The residual loads were measured at 15mm displacement.The loaddisplacement results for two deformed bar Secura bolts (bolts 1 and 2; bolt core 23 mm, rib 27 mm) installed within 3738mm holes are shown in Fig. 12. The results show that a significant difference in load transfer was experienced for the similar embedment lengths tested. The weakest section of the bolt was detected at the toe region of the bolts, which is considered a poor result. In both cases, the failure occurred at the resinrock interface. Evidence of poorly mixed resin is shown in Fig. 13.Fig. 14 shows the loaddisplacement results for three Posimix bolts (bolts 3, 4 and 5; bolt core 20 mm, rib 23 mm) installed within 3738mm diameter holes. A large load transfer variability can be interpreted from the results. In particular, bolt number 4 showed poorly mixed resin, with failure at the boltresin interface (see Fig. 15).Table 1 Summary of laboratory testing resultsFig. 12. Load vs. displacement plot for 20mm Secura bolts.Fig. 13. Example of poorly mixed resin (layers observed).Fig. 14. Load vs. displacement plot for 20mm Posimix bolts.Fig. 15. Details of bolt inspection following testingfailure at bolt/resin interface and weak resin is shown.8. Resin mixing qualityIn order to compare the mix quality between a number of commercially available bolts, a rating system was developed and applied to a large number of overcored samples 8. A scoring system consisting of good was used to indicate samples that had no plastic and no voids and the resin appeared well mixed, poor was used to indicate samples that had plastic and voids and the resin appeared poorly mixed. Similarly, a third rating, inconclusive, was introduced for samples where either no plastic or voids could be identified and the mix did not rate as good or poorly mixed (see Fig. 16). The scoring system is calculated by adding numbers used to quantify the presence of plastic packaging and voids as follows: Plastic present: No2 points, Yes1 point Mix quality: Good2 points, Poor1 pointThe resulting scores are indicated by poor (2 points), inconclusive (3 points) and good quality (4 points).Fig. 16. A comparison of resin mix quality for a number of reinforcement schemes.The scoring system was also used to compare sections of the bolt; i.e. collar, mid-section and toe regions. The results show that for all reinforcement systems, the majority of the poorly mixed samples were located at the anchoring region (see Fig. 17). This is perhaps due to different mixing times along the bolt axis and also due to accumulation of the resin cartridge plastic as it is pushed towards the end of the hole. Resin mixing time for the end of the hole is less than the rest of the bolt, thus increasing the risk of a poor mix.Bolt overcoring data from another mine site also shows that the best resin mixing and bolt encapsulation occurs within the middle region of the bolts (see Fig. 18). Only 20% of the observed sections within the critical toe region had no problems.Overcoring results for similar reinforcement systems also suggest encapsulation quality (and load transfer) variability along a bolt axis. Fig. 19 shows overcoring results for 27mm Secura bolts installed in basalt at the Bullant Mine near Kalgoorlie, Western Australia, using 33 and 35mm holes. Similar embedement lengths (300 mm) were tested. The results show that similar strengths were found for the collar and toe regions, with increased strengths for the middle regions where resin mixing appear to be more effective.Fig. 17. Resin encapsulation quality for a number of commercial reinforcement systems.Fig. 18. Resin encapsulation inspection along the bolt axis.Fig. 19. Load transfer variability along bolt axis for Secura bolts in Mount Pleasant basalt.9. ConclusionsThe overcoring data show that for the majority of the current bolthole size combinations, reinforcement systems and installation practices used in the Australian hard rock mining industry, the best resin mixing and bolt encapsulation occurs within the middle region of the bolt. In all cases of low load transfer, poor resin mixing was identified as the main cause. In addition, the majority of the overcored bolts had no resin at the collar region, indicating that effective plating of the bolts is very important for long-term effectiveness. The worst conditions in terms of encapsulation and load transfer are found towards the toe region of the bolts.AcknowledgementsThe authors wish to acknowledge the financial support of the Minerals and Energy Institute of WA (MERIWA), WMC Resources Ltd., Placer Dome Asia Pacific, Xstrata Ltd., Barrick Gold Australia, Goldfields Australia, Degussa (MBT Australia), Strata Control Systems, AVKO Drilling and the WA School of Mines. The review of this work by Alan Thompson and Chris Windsor is gratefully acknowledged.References1 Windsor CR. Rock reinforcement systems. Int J Rock Mech Min Sci Geomech Abstr 1996;34(6):91951.2 Villaescusa E. The reinforcement process in underground mining. In:Villaescusa E, Windsor CR, Thompson AG, editors. 4th International Symposium on Rock Support and Reinforcement Practice in Mining, Kalgoorlie. Rotterdam: Balkema; 1999. p. 24558.3 Hyett A, Bawden W, Reichard R. The effect of rock mass confinement on the bond strength of fully grouted cable bolts. Int J Rock Mech Min Sci Geomech Abstr 1992(29):50324.4 Kaiser P K, McCreath D R, Tannant D. Canadian rockburst support handbook. Sudbury: Geomechanics Research Centre; 1900 300p.5 Windsor CR, Thompson AG. Rock reinforcementtechnology testing, design and evaluation. In: Hudson J, editor. Comprehensive rock engineering, vol. 4 (issue 16). Oxford: Pergamon Press; 1993.p. 45284.6 Tannant D, Kaiser P K, Maloney S. Loaddisplacement properties of welded-wire, chain-link and expanded metal mesh. In: Broch E, Myrvang A, Stjern G, editors. International Symposium on Rock Support Applied Solutions for Underground Structures. Lillehammer; 1997. p. 6519.7 Tannant D, Kaiser P K. Evaluation of shotcrete and mesh behaviour under large imposed deformations. In: Broch E, Myrvang A, Stjern G, editors. International Symposium on Rock Support Applied Solutions for Underground Structures. Lillehammer; 1997. p. 78292.8 Villaescusa E, Wright J. Permanent excavation reinforcement using cement grouted split set bolts. AusIMM Proc 1997;1:659.9 Thompson AG, Finn D. The performance of grouted split tube rock bolt systems. In: Villaescusa E, Windsor CR, Thompson AG, editors. 4th International Symposium on Rock Support and Reinforcement Practice in Mining, Kalgoorlie. Rotterdam: Balkema; 1999. p. 91102.10 Mikula P. Changing to the Posimix4 for Jumbo and Quick-ChemTM at Mount Charlotte Mine. In: Villaescusa E, Potvin Y, editors. Proceedings of 5th international symposium on ground support. Perth: Taylor & Francis; 2004. p. 21120.11 Simpson SJ. Evaluation and implementation of resin bolts at Olympic Dam Mine. Bachelor of engineering thesis, WA School of Mines; 2005.12 Varden R. A methodology for selection of resin grouted bolts. Master of engineering science in mining geomechanics thesis, WA School of Mines; 2005.13 Kaiser P K, Tannant D, McCreath D. Drift support in burst prone ground. Can Min Metall Bull 1996;89(998):1318.14 Thompson AG, Windsor CR. Theory and strategy for monitoring the performance of rock reinforcement. In: Szwedzicki T, editor. Proceedings of Geotechnical Instrumentation and Monitoring in Open Pit and Underground Mining, Kalgoorlie. Rotterdam: Balkema; 1993. p. 47382.15 Windsor CR, Thompson AG. Reinforcement design for jointed rock masses. In: Proceedings of 33rd US symposium on rock mechanics, Santa Fe. Rotterdam: Balkema; 1992. p. 52130.16 Mould RJ, Campbell RN, MacGregor SA. Extent and mechanisms of gloving and unmixed resin in fully encapsulated roof bolts and a review of recent developments. In: Villaescusa E, Potvin Y, editors. Proceedings of 5th international symposium on ground support. Perth: Taylor & Francis; 2004. p. 23142.17 Brown ET, editor. Rock characterization testing and monitoring. Commission on testing methods, International Society for Rock Mechanics. Oxford: Pergamon Press; 1978. p. 1638.18 Compton C, Oyler D. Investigation of fully grouted roof bolts installed under in-situ conditions. In: Peng S, et al., editors. Proceedings of 24th international conference on ground control in mining, Morgantown; 2005. p. 30212.19 Beard MD, Lowe MJ. Non-destructive testing of bolts using guided ultrasonic waves. Int J Rock Mech Min Sci 2003;40: 52736.20 Hassell R, Villaescusa E. Overcoring techniques to assess in situ corrosion of galvanized friction bolts. In: Gurgenci, et al., editors. Proceedings of Australian mining technology conference. Fremantle: The AusIMM; 2005. p. 97110.21 Pettibone HC. Avoiding anchorage problems with resin grouted bolts. USBM RI 9129; 1987. 28p.中文译文澳大利亚地下硬岩矿山树脂锚杆的性能量化E .维拉斯库萨，R.瓦尔顿，R.哈塞尔澳大利亚西部矿业学校, 港口及航运局22, 卡尔古利6430, 澳大利亚澳大利亚巴力克, 邮政信箱1662, 卡尔古利6433, 澳大利亚1 引言围岩支护和加固的目的是确保在预期的服务年限内开掘巷道的安全和开放，一个加固策略有效性的重要性主要是以下两个原因：一是确保对人员和设备的安全，二是能够达到最佳的经济效益。对于一特定的岩块，能匹配预期行为的支护方式的选择是根据有可能失败模型的评估，这个模型来自于开掘之间的联系（几何空间和用途），地址不连续网络，气候条件以及压力爆炸破坏的承载情况。在大多数地下煤矿，稳定开挖的主要形式是由一种类型安置于岩石内部的锚杆所提供，这是在使用被动支护下完成支护，比如说利用锚网或喷射混凝土来控制围岩表面位移在制定的开挖界限之内。锚杆加固是通过键入、加拱或组合梁加固作用来控制开挖的稳定性，与此同时，锚网或喷射混凝土支护锚杆托盘之间可能脱落的小且松散岩块。通常来说，一个支护方式的选择需要考虑地面支护钻孔设备能否使用在特定的煤矿，现代最佳的方案将包括在单一巷道中进行加强和支护的机械化安装，这是为了增加产量，减少人员暴露时间和减少安装过程中的设备。2 机械化树脂锚杆安装在过去的十年左右，安装超大，45毫米直径镀锌，黑钢摩擦锚杆稳定已经成为澳大利亚地下煤矿支撑加固的首选形式。为了能够开采低品位矿体而要求达到快的发展速度和低成本，这驱使了支护方式的改变。在最近几年，随着采矿作业越来越深，岩体强度越来越大，其他的支护方式，比如完全封装树脂锚杆，被视为是一种替换摩擦锚杆进行的长期支护。这种典型的使用于地下硬岩矿山的锚杆改装于煤炭开采业使用的锚杆，由于需要使用在硬岩金属矿山型号的设备来钻超大直径的孔洞，这种修改是必要的。修改主要以桨的形式或者使用弹簧焊接到锚杆的最后一节，图1展示了锚杆部分的两种排列形式，一是24毫米Posimix锚杆的弹簧式排列，一是27毫米Secura锚杆的桨状排列。Posimix线的直径3毫米，长500毫米，桨的宽度为29.2毫米，为了混合树脂而将桨折减至锚杆的尾部。图1 Posimix和Secura锚杆各自的弹簧和桨状排列然而，因为树脂运输和储藏的成本高，引进巨型机械化树脂锚杆就很难经济地实施，这要求使用冷藏车，地面和地下的存储设备，此外还存在其他的问题，包括锚杆安装速度，其中在单一巷道安装网的能力，锚杆直径与超大直径钻孔匹配差以及操作人员的技能问题。3 荷载传递的概念根据荷载在支出结构和岩体之间转移的基本机制，全长锚固类锚杆被归类为机械化连续耦合锚杆。机械化连续耦合支护结构（英文缩写CMC）取决于一个固定剂，通常是用水泥或者树脂底部灌浆，以此充填结构与钻孔壁之间的纤维环。灌浆的主要作用是为荷载在岩体与支护结构之间转移而提供的一个机制。荷载转移概念对于理解完全封装树脂锚杆如何确保开挖稳定非常重要，温莎和汤普森通过如下列举的三个基本单个组件解释了这个概念（如图2所示）：1、岩石在裸露的开挖边界发生运动，从而导致荷载从一个不稳定的区域（楔形或平板）转移到支护结构上；2、通过支护结构，荷载从不稳定的部分转移到岩体内部稳定的地区；3、支护结构上的荷载转移到稳定区域的岩体。在三个独立的组成部分中任一荷载转移期间，由于不稳定区域岩体恶化，钢承载力不足（支护结构的破裂）或者荷载转移不充分（滑移），被支撑岩块可能产生崩落。为了增加结构荷载转移，支护结构常被制成可变截面形状。通过沿着整个支护长度支护结构和灌浆之间的几何干扰，机械键有效地产生了，这种构件被定义为通过灌浆剂连锁方式与岩体形成的连续耦合。图2 完全封装支护结构的荷载转移概念就树脂锚杆而言，原位拉力测试实验数据说明锚杆在埋设长度短的时候能得到高强度的转移荷载。然而，墨盒树脂系统可能产生欠旋转和超旋转两种结果。欠旋转导致混合不均匀，树脂强度低，常发生于钻孔的锚杆尾部，在一些情况下，树脂将不会凝固。在安装时超旋转可能导致部分固化树脂的折断，这将会减少连接区域和降低荷载转移，此外，通过塑料包装，锚杆可能产生变形，这将完全使荷载不能沿锚杆轴线转移。4 传统质量控制支护方式的性能和极限承载力可能会因不合标准的安装方法受影响，然而，在CMC支护中，错误的安装很难发现，仅仅看得到的构件是托盘，螺母和一短截用来指示相对于开挖墙壁安装方向的锚杆。因此，对于完全封装树脂锚杆来说，确定沿锚杆整个轴线的结合长度（锚杆埋置深度）是很困难的。除此之外，锚杆的极限承载力可能因高质量树脂埋置深度浅而增强，所以在锚杆支护结构中对露在外面的锚杆进行拉力测试基本上没有意义。国际岩石力学协会建议进行的拉力测试仅仅对树脂有效性提供一种指示，测试位置在孔口或沿锚杆轴线第一个位置（未知），此时树脂能有效地工作。同时，拉力测试仅仅提供对差的安装情况有限的说明，在这种情况下，整个长度的树脂锚杆支护远不及设计的承载能力。短长度的树脂封装测试因其不能在一个完整的规模测试提供树脂混合测量方法，故不能用来进行质量控制。传统的进行质量控制的拉力测试方案仅有意义地应用于点锚定或者摩擦型锚杆，此外，在澳大利亚，非破坏性的超声波探测方法要么仍处于发展或没有得到广泛应用。5 锚杆钻孔取样由于紧迫和压倒一切地需要检查完全封装原位锚杆的整个长度，一个专用的钻机便开始形成，这个钻机能够在生产矿山环境中钻孔安置锚杆。西澳大利亚州矿业学院（英文缩写WASM）研究发明了一个全面的钻孔系统，这个系统能够360度任意角度钻眼，钻孔深度可达3米，原位锚杆钻孔能在墙壁和背部进行大约5到7米领口的高度，WASM钻机打钻如图3所示。图3 WASM锚杆钻孔取样施工仔细钻探和合适的置入锚杆速度使直径140毫米的钻孔在用摩擦稳定的条件差岩体的情况下只产生最小的干扰，这不仅需要支护的恢复能力，还需要对周围岩体以及锚杆系统和岩体相互作用有一个清晰的理解与掌握，如图4所示。图4 低劣岩体中摩超钻擦型锚杆的完全恢复锚杆钻孔取样提供一系列包含位置，地质不连续的频率，整个岩体的情况，锚杆封装程度，荷载沿锚杆轴线的转移以及腐蚀影响等的信息。破碎或剪切带的钻孔取样表明在超大树脂锚杆中发生了极少的树脂移动，树脂简单地填充了锚杆与钻孔之间的纤维环，树脂因其粘性而不能渗入岩体的裂缝和空隙，如图5所示，比较而言，在差的地面条件下进行水泥灌浆锚杆钻孔时观察到了显著的水泥移动，如图6所示。使用水泥灌浆锚杆时岩体相互作用的程度远超过用树脂灌浆锚杆或摩擦型稳定时，地下开挖时岩体相互作用已被作为利用岩体自承的一种重要的机制。钻孔取样同样可以提供关于孔洞超挖的信息，孔洞超挖很可能导致锚杆在端口区域不能充分填充封装，这是因为在钻孔底部的树脂移动到超挖的部分空间，如图7所示。图5 大型剪切带的细微树脂转移图6 破碎岩体通过水泥灌浆处理形成的联锁效果图7 锚杆领区差的封装和孔洞超钻的例子6 实验测试西澳大利亚州矿业学院发明了一种实验程序来评测钻孔取样锚杆封装质量和荷载转移的性能，通过钻孔取样，这些样本被运到西澳大利亚州矿业学院，每个样本根据位置标记，并从中截取合适的部分来测试力-位移特性。力-位移曲线通常能够提供对刚度，峰值，残余势力以及位移承载能力等的反应，结果可用来作为对沿锚杆轴线方向荷载位移（安装质量和锚杆有效性）的一个相对的测量。在实验中常用来做拉力测试的埋置深度是300毫米，然而，常用拉力测试需要样本的总长度为700到800毫米中的最小值，因此，对于2.4米长的锚杆可以选择3个样本进行拉力测试，这就需要锚杆端部和顶部封装和荷载转移的变化。一个典型的拉力测试需要一个300毫米的岩石块件和一个400到500米长的裸露的钢条，去掉一部分岩块留出一个部分裸露的部分，如图8所示，剩下的岩块部分放在一个金属外套来模拟由原位岩体产生的径向约束，然后拉构件外露的部分，并用一个金属板限制300毫米部分长锚杆的运动，如图9所示。图8 测试前钻孔取样锚杆准备的短部分图9 300毫米埋设长度的典型拉力测试通过岩体拉出构件的力和相应的位移可以数字化记录，然后随着测试对构件进行观察并拍照，结果表明，在大多数情况下，当荷载转移有效时，树脂与岩体界面处的树脂锚杆将失效。摩擦阻力由锚杆与树脂界面处树脂不规律地剪切而移动变化，然而，当树脂封装不好时，锚杆与树脂界面处将发生失效，这就说明不好的安装将导致树脂不充分的混合，如图10所示。图10 a有效荷载转移和b过度树脂墨盒包装的例子手套包装这个术语是用来描述通过塑料包装对锚杆进行封装或部分封装，它已被使用多年，最开始是用于煤炭开采业，被许多人报道过，其中包括佩蒂伯恩。对gloving发生的解释已被用来设计锚杆和树脂墨盒的特性，安装质量，洞口尺寸，钻孔设备以及操作储藏方法等。通过钻孔取样观测的另一个现象是锚杆树脂的侧向位移，当锚杆直径比洞口尺寸显著小时，这个现象就发生了，如图11所示。7 典型的力 - 位移结果表1展示了一系列钻孔取样的结果，分别在非锚固区（样本A）和锚固区（样本B）沿着一个特别的锚杆轴线选择相同埋设长度的样本进行比较，残余荷载测得发生15毫米的位移。图11 树脂侧向移动的例子两个螺纹钢Secura锚杆（锚杆1和锚杆2）安装在37到38毫米直径的钻孔，其载荷-位移结果如图12所示，结果表明对于所测试的同样埋设长度的锚杆，其荷载转移有显著的不同。在锚杆的顶部测得锚杆最薄弱的部位，这被认为是不好的结果，在以上两种情况下，锚杆在树脂与岩体界面处失效，差的树脂混合数据如图13所示。表1 实验测试数据汇总图12 20毫米直径Secura锚杆荷载-位移曲线图