英文翻译-Rockbolts and cables 岩石锚杆和锚索

英文 翻译 阿房宫赋翻译下载德汉翻译pdf阿房宫赋翻译下载阿房宫赋翻译下载翻译理论.doc -Rockbolts and cables 岩石锚杆和锚索 河北工程大学毕业设计( 论文 政研论文下载论文大学下载论文大学下载关于长拳的论文浙大论文封面下载 ) 本科毕业设计(论文) 英语翻译译文 题目:Rockbolts and cables 岩石锚杆和锚索 学生姓名: 专 业: 勘查技术与工程 班级学号: 指导老师: 指导教师职称: 教授 2013年 5 月 10 日 河北工程大学毕业设计(论文) Rockbolts and cables Rockbolts and dowels have been used for many years for the support of underground excavations and a wide variety of bolt and dowel types have been developed to meet different needs which arise in mining and civil engineering. Rockbolts generally consist of plain steel rods with a mechanical anchor at one end and a face plate and nut at the other.they are always tensioned after installation.For more permanent applications or in rock in which corrosive groundwater is present,the space between the bolt and the rock can be filled with cement or resin grout. Dowels or anchor bars generally consist of deformed steel bars which are grouted into the rock.Tensioning is not possible and the load in dowels is generated by movements in the rock mass.In order to be effective ,dowels have to be installed before significant movement in the rock mass have taken place.The rockbolt and dowel applications can be used to control different types of failure that occur in rock masses around underground opennings. The move towards larger underground excavations in both mining and civil enginneering has resulted in the gradual development of cable reinforcement technology to take on the support duties which exceed the capacity of traditonal rockbolts and dowels. Expansion shell rockbolt anchors come in a wide variety of styles but the basic principle of operation is the same in all of these anchors.The components of a typical expansion shell anchor are a tapered cone with an interal thread and a pair of wedges held in place by a bail.The cone is screwed onto the threaded end of the bolt and the entire assembly is inserted into the that has been drilled to receive the rockbolt.The length of the hole should be at least 100mm longer than the bolt otherwise the bail will be dislodged by being forced against the end of the hole.Once the assembly is in place,a sharp pull on the end of the bolt will seat the anchor.Tightening the bolt will force the cone further into the wedge thereby increasing the anchor force. These expansion shell anchors work well in hard rock but they are not very effective in closely jointed rocks and in soft rocks,because of deformation and 1 河北工程大学毕业设计(论文) failure of the rock in contact with the wedge grips. At the other end of the rockbolt from the anchor,a fixed head or threaded end and nut system can be used.In either case,some form of faceplate is require to distribute the load from the bolt onto the rock face.In addition,a tapered washer or conical seat is needed to compensate for the fact that the rock face is very seldom at right angles to the bolt.A wide variety of faceplates and tapered or domed washers are availbable from rockbolt suppliers. In general,threads on rockbolts should be as coarse as possible and should be rolled rather than cut.A fine thead is easily damaged and will cause installation problems in a typicle underground environment.A cut thread weakens the bolt and it is not unusual to see bolts with cut threads that have failed at the first the thread at the back of the nut.Unfortunately,rolled thread bolts are more expensive to manufacture and the added cost tends to limit their application to situations where high strength bolts are required. Tensioning of rockbolts is important to ensure that all of the components are in contact and that a positive force is applied to the rock.In the case of light “safety” bolts,the amount of tension applied is not critical and tightening the nut with a conventional wrench or with a pneumatic torque wrench is adequate.Where the bolts are required to carry a significant load,it is generally recommended that a tension of approximately 70% of the capacity of the bolt be installed initially.This provides a known load with a reserve in case of additional load being induced by displacements in the rock mass. One of the primary causes of rockbolt failure is rusting or corrosion and this can be counteracted by filling the gap between the bolt and the drillhole wall with grout.While this is not require in temporary support application,grouting shoud be considered where the ground-water is likely to induce corrosion or where the bolts are require to perform a “permanent” support function. The traditional method of grouting uphole rockbolts is to use a short grout tube to feed the grout into the hole and a smaller diameter breather tube,extending to the end of the hole,to bleed the air from the hole.The breather tube is generally taped to bolt shank and this tends to cause problems because 2 河北工程大学毕业设计(论文) this tube and its attachments can be damaged during transportation or insertion into the hole.In addition,the faceplate has to be drilled to accomomodate the two tubes.Sealing the system for grout injection can be problem. Many of these difficulties are overcome by using a hollow core bolt.While more expensive than conventional bolts make the grouting process much more reliable and should be considered wherever permanent rockbolt installations are require.The grout should be injected through a short grout tube inserted into the collar of the hole and the central hole in the bolt should be used as breather tube.When installing these bolts in downholes,the grout should be fed through the bolt to the end of the hole and the short tube used as a breather tube. Since the primary purpose of grouting mechanically anchored bolts is to prevent corrsion and the lock the mechanical anchor in place, the strengh requirement for the grout is not as important as it is in the case of grouted dowels or cables.The grout should be readily pumpable without being too fluid and a typicle water/cement ratio of 0.4 to 0.5 is a good startina point for a grout mix for this application.It is most important to ensure that the annular space between the bolt and the drillhole wall is completely filled with grout.Pumping should be continued until there is a clear indication that the air has stopped bleeding through the breather tube or that grout is seen to return through this tube. A comprehensive review of cable support in underground mining has been given in a book by Hutchinson and Diederichs(1996). Some of the main cable types used by mining have been summarised by Windsor(1992) and are illustrated in some books. 1 Bond strength As the cable pulls out of the grout, the resultant interference of the spiral steel wires with their associated grout inprints or flutes causes radial displacement or dilation of the interface between the grout and the cable.The radial dilation induces a confining pressure that is proportional to the combined stiffness of the grout and the rock surrounding the borehole.The shear 3 河北工程大学毕业设计(论文) stress,which resists sliding of the cable,is a product of the confining pressure and the coefficient of friction between the steel wires and the grout.Shear strength,therefore,increases weth higher grout strength,increases in the grout and the rock stiffness and increases in the confining stresses in the rock after installation of the cable.Conversely,decrease in shear strength can be expected if any of these factors decrease or if the grout crushes. 2 Grouts and grouting The question of grout quality has always been a matter of concern in reinforcement systems for underground construction.One of the critical factors in this matter has been the evolution of grout pumps capable of pumping grouts with a low enough water/cement ratio (by weight) to achieve adequate strengths.Fortunately,this problem has now been overcome and there is a range of grout pumps on the market which will pump very viscous grouts and will operate reliably under typical underground conditions. The results of a comprehensive testing programme on Portland cement grouts have been summarised by Hyettetal (1992) and the results show that the properties of grouts with water/cement ratios of 0.35 to 0.4 are significantly better than those with ratios in excess of 0.5.However,Hyettetal found that the scatter in test results increased markedly for water/cement ratios less than 0.35.The implication is that the ideal water/cement ratio for use with cable reinforcement lies in the range of 0.35 to 0.4. 4 河北工程大学毕业设计(论文) 岩石锚杆 多年来，岩石锚杆和锚栓已经应用于地下工程开挖支护中，人们开发了各种各样的岩石锚杆和锚栓以满足在采矿和土木工程等不同方面的需求。 岩石锚杆通常由一端具有机械锚头、另一端具有垫板和螺帽的普通钢筋构成。它们在安装后通常进行张拉。对短期使用来说锚杆一般不进行注浆。对长期使用或岩石中的地下水具有腐蚀性时，锚杆与岩体之间的间隙用水泥或树脂填注。 锚栓或锚固钢筋一般由插入岩石的成型钢筋组成并注浆。不可能发生张拉，锚栓的荷载有岩体的变位而引起。为了使这些锚栓起作用，必须在岩体发生明显位移之前安装。在工程上采用的岩石锚杆和锚栓，可用于控制地下硐室围岩所发生的不同形式的破坏。 在采矿工程和土木工程中，地下工程规模越来越大的趋势带动了锚索加固技术的不断发展，它所起的作用，超过了传统的岩石锚杆和锚栓。 胀壳式岩石锚杆具有各种各样的类型，但是，在所有这些锚杆中，工作基本原理是相同的。典型的胀壳式锚杆有带内丝的锥形螺母和由顶板固定的一对楔形体。锥形螺母在锚杆具有螺丝的一端被拧紧，整个装配过程是将锚杆插入已钻成的锚杆孔内。孔的长度至少要比锚杆的长度长100mm，否则，顶板将由于钻孔末端的作用力使卡箍卸载。一旦装配到位，将锚杆末端猛地一拉，使锚杆到位。上紧锚杆迫使锥体进入楔形体，从而增加锚固力。 胀壳式锚固器在坚硬岩石中工作良好，但在与楔形体啮合的节理带和软岩中由于岩石变形破坏，这种方法不是非常有效。 锚固器锚杆的一端，可以采用固定头和螺帽系统。在任一情况下，均需要某种类型的垫板将锚杆的荷载传到岩石 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 面上。另外，因为岩石表面很少与锚杆成正交，需要一个锥型垫或锥型座进行调整。岩石锚杆生产商供应各种各样垫板或圆型垫圈。 一般来说，岩石锚杆的螺纹应尽可能粗，并且应该是轧制螺纹而不是切割螺纹。细螺纹容易损坏，并且在典型的地下环境中容易产生安装问题。切割螺纹使锚杆弱化，经常价格昂贵，增加的费用限制了它只能在需要高强度锚杆的地方使用。 岩石锚杆的张拉重要的，它要保证所有的部分相互接触，并且在岩石上施加压力。在使用对安全性要求较小的锚杆时，所施加的张力的大小并不重要，使用常规的扳手或气压扭矩式扳手拧紧螺帽就已经足够。在需要锚杆承担大荷载的地方，一般建议在安装的初期，施加锚杆的张力为允许荷载的70% 。在岩体中因位移产生附加荷载时，这种做法提供了一个保守的已知的荷载。 岩石锚杆破坏的主要原因之一是锈蚀或腐蚀，这些可以采用在锚杆和钻孔孔壁之间 5 河北工程大学毕业设计(论文) 充填将夜的办法进行防治。这些措施在临时支护时并不需要，但是在地下水有可能产生腐蚀作用或锚杆需要作为永久支护的地方，应尽可能考虑使用注浆锚杆。 在方向向上的岩石锚杆钻孔中进行注浆的传统方法是使用短注浆管把浆液注入钻孔中，将一个直径较小的排气管插到钻孔底部，从钻孔中排气。排气管通常和锚杆捆绑在一起，这种方法又是会产生问题，因为这些排气管和它的捆扎物在运输或插进钻孔的过程中可能会遭受破坏。此外还要在面板上钻孔，以容纳排气管和注浆管的需要。此外，注浆系统的封闭也可能存在问题。 很多此类困难均可以采用空心锚杆克服。这种锚杆比常规锚杆要贵，但它使注浆过程更可靠，可以在需要安装永久锚杆的地方考虑使用这种锚杆。浆液通过一个短的注浆管注浆直到钻孔周边，锚杆的中心孔用做排气管。当在向下的钻孔中安装这类锚杆时，注浆应通过锚杆灌倒钻孔底端，短管用做排气管。 从机制上讲，注浆的目的是要防腐蚀并把机械锚头固定到相应的部位，注浆的强度要求不像对注浆锚栓或锚索要求的那样重要，浆液应该能用泵抽送并且不太稀，一般情况下，采用水灰比为0.4~0.5的浆液混合物十分可行。保证锚杆和钻孔孔壁之间的环形孔隙完全充填浆液很重要。泵送应该连续进行，直到有清楚的证据表明，排气管不在排气或浆液已经开始从排气管排出为止。 Hutchinsion和Diedeichs(1996)在其著作中全面总结了锚索支护在地下采矿业中的应用。Windsor(1992)在一些著作中总结了采矿业中使用锚索的主要类型。 一、粘结强度 当锚索从浆体中拔出来时，螺旋状钢绞线与相关的注浆印痕或凹槽所引起的相互作用会引起锚索与注浆界面之间径向膨胀和位移。径向膨胀会减小围压，此围压与浆体和钻孔周围岩石综合刚度成正比。阻止锚索滑动的剪应力由围压和钢绞线与浆体之间的摩擦力产生。因此，在锚索安装以后，抗剪强度随浆体强度的增加而增加。反过来讲，如果这些值减小或浆体破裂，抗剪强度可能会减小。 二、浆体和注浆 在地下工程中，浆体的质量总是涉及到加固问题。其中的一个主要因素是灌浆泵的发展，灌浆泵应该能泵取相当低水灰比(按重量)的浆液同时也能达到足够的强度。值得庆幸的是，这些难题已经克服，市场上有各种各样的灌浆泵可泵取很粘的浆液，在特殊的地下条件下，可以可靠地工作。 Hyettal(1992)等对波兰(Protland)水泥浆液的综合试验结果进行了总结。结果表明水灰比为0.35~0.4的浆液性质要水灰比超过0.5的浆液好很多。然而Hyettal等发现水灰 6 河北工程大学毕业设计(论文) 比小于0.35的浆液，试验结果的离散性显著增加。这意味着用于锚索加固的理想水灰比应位于0.35 ~0.4之间。 7