串联拉索沿导索空中累积滑移施工关键技术及FAST工程应用研究

发布时间：2018-04-28 11:05

本文选题：FAST反射面支承索网 + 串联拉索　；参考：《东南大学》2015年硕士论文

【摘要】：我国利用中国贵州喀斯特洼地,建造500m口径具有主动反射面的大型射电望远镜FAST (Five-hundred-meter Aperture Spherical Telescope)。其中,FAST主动反射面的支承结构属于巨型空间结构。主索网固定在周圈环梁上,下拉索下端与地面促动器相连以控制整个索网变形。主索网水平投影直径达到500m,最高点到最低点的落差达到134.0m。FAST主动反射面主体支承结构由主索网、下拉索、格构式圈梁和格构式钢柱以及格构柱基础组成。主索网为短程线型三角形网格,除边界节点外每个主索网节点连接6根主索和1根下拉索,共2225个主索节点,合计约400t,6670根主索和2225根下拉索,约1170吨,主索长度为11.0m左右,下拉索长度在4.0m至60.0m之间不等,索体采用OVM.ST型高应力幅拉索体系。建设场地为喀斯特洼地,洼地呈“锅状”,但其形状与理想球面相距甚远,仅在洼地底部有较为平坦的场地,拉索无法在地面展开进行组装,不能进行整体提升,搭设满堂支撑塔架平台安装的方法也不可行。因为周圈钢圈梁施工完成后再进行索网施工,所以可以考虑借助周圈钢圈梁进行空间牵引安装。根据索网结构的对称性,索网结构划分为5+1个区域施工,其中1个区域为支撑塔架安装区,5个对称区域由沿导索牵引安装区和扩展部分安装区组成。其中支撑塔架安装区先施工安装完毕,接着安装对称轴位置的拉索,然后对称向两侧扩展施工。主索和下拉索安装完成后,促动器预紧张拉下拉索。本文根据索网结构特点,提出了串联拉索沿导索空中累积滑移安装方法,即将串联的结构索通过吊杆或倒链葫芦挂在导索下,利用牵引索将拉索由下至上沿导索累积牵引就位。串联拉索沿导索空中累积滑移安装施工方法主要运用于对称区域索网径向索的安装。该方法充分发挥了导索既导向又承重的作用,构成简单,施工措施费用低。牵引过程中存在包括松垂拉索、滑移的机构大位移,结构索、导索和牵引索的索力和位形相互影响大,应进行牵引过程分析,掌握过程中各索力和整体位形的变化规律,确定合理的施工参数,包括：导索和牵引索的最大拉力、导索安装无应力长度(简称原长)等。其过程分析方法,是基于NDFEM法找形,根据导索单元组总原长不变的原则,采用调整导索各单元原长的方法来模拟滑轮在导索上的移动,并提出和对比了四种策略,通过算例分析,指出“逐单元递推倍增”策略具有更高分析效率。分别设定导索原长为主索原长、端点距离和中间值,采用“逐单元递推倍增”策略分析对比三种原长下的分析模型。指出了关键施工参数的变化规律,得出：(1)导索线形在起始工况是最不利的,导索原长不宜过长且不应超过主索原长；(2)导索和牵引索的索力变化受导索原长影响大,且较为敏感；(3)合理的导索原长应介于主索原长和两端距离之间。对对称轴处沿导索牵引安装区索网的施工过程分析时,取出一根导索进行施工方法及施工过程分析方法的研究。采用“逐单元递推倍增”策略进行对比分析,得出了与算例基本相符的结果,同时根据计算结果,得出了实际施工时所需要的施工参数,包括：导索无应力长度和拉力、牵引索拉力等。本文根据沿导索牵引安装区的导索和扩展部分安装区的猫道下端锚固位置,并结合施工现场情况确定了独立塔架的布置位置。通过对沿导索牵引安装区和扩展部分安装区进行施工过程分析,得到导索和猫道索对下锚固点的作用力。根据作用力大小及方向,确定了通过单层平面桁架连接独立塔架增加结构整体性,通过设置背索减小塔架负担的塔架总体设计方案。根据施工过程设定多组荷载组合,对塔架进行了施工过程分析,确定了一套切实可行的施工方案。作为高精度的天文望远镜,FAST索网支承结构的制作和安装精度要求都非常高,所以精度控制就异常重要。本文对索网结构进行误差敏感性分析,确定误差因素及其敏感性程度,并结合实际施工可达到的精度,确定施工精度控制指标,为索网施工的精度控制提供依据。
[Abstract]:China uses the Karst depression in Guizhou, Guizhou, China to build a large radio telescope FAST (Five-hundred-meter Aperture Spherical Telescope) with an active reflector. Among them, the supporting structure of the FAST active reflector is a giant space structure. The main cable net is fixed on the circumferential ring beam and the lower end of the lower cable is connected with the ground actuators. Control the whole cable net deformation. The horizontal projection diameter of the main cable network reaches 500m, the maximum point to the lowest drop reaches the main support structure of the 134.0m.FAST active reflector, which consists of the main cable net, the lower cable, the lattice beam and the lattice steel column and the lattice column foundation. The net node connects 6 main cables and 1 lower cables, with a total of 2225 main cable nodes, with a total of about 400t, 6670 main cables and 2225 lower cables, about 1170 tons, the length of the main cable is about 11.0m, the length of the cable is between 4.0m and 60.0m, and the cable body uses the OVM.ST type high stress cable system. The construction site is the Karst depression, the low-lying land is "pot like" in the low-lying land. The shape is far away from the ideal sphere, and there is a relatively flat site at the bottom of the depression. The cable can not be assembled on the ground and can not be promoted as a whole. It is not feasible to set up the installation method of the full support tower platform. Because the steel ring beam of the circle ring is completed after the construction is completed, it can be considered by the circumferential steel ring beam. According to the symmetry of the cable network structure, the cable net structure is divided into 5+1 area construction, of which 1 areas are the support tower installation area, the 5 symmetrical areas are composed of the lead cable traction and installation area and the extended part installation area. After the installation of the main cable and the lower cable is completed, the actuators are pretense to pull down the cables after the installation of the main cables and the lower cables. In this paper, according to the characteristics of the cable net structure, a method of accumulative slip installation in the air of a series cable is put forward, and the connecting cable is hung under the guide cable through the hanger or the chain hoist, and the cable is made of the cable from the bottom to the top. The construction method of the cumulative sliding of the cable in the air is mainly applied to the installation of the radial cable of the cable net in the symmetrical area. This method fully exerts the effect of guiding and bearing of the guide cable. The construction is simple and the cost of the construction measures is low. The cable, cable and traction cable have great influence on the cable force and the shape of the cable. We should carry out the analysis of the traction process, grasp the change law of the cable force and the overall position in the process, and determine the reasonable construction parameters, including the maximum pulling force of the guide cable and traction cable, the installation of the guide cable without stress length (simply called the original length) and so on. The process analysis method is based on the NDFEM method. According to the principle of the invariability of the total length of the unit group, the method of adjusting the original length of the guide cable is used to simulate the movement of the pulley on the guide cable. Four kinds of strategies are proposed and compared. Through an example analysis, it is pointed out that the strategy of "unit by unit recurrence multiplication" has higher analysis efficiency. And the intermediate value, using the "unit by unit recurrence multiplication" strategy analysis and comparison of the three original analysis models. The change law of key construction parameters is pointed out. (1) the line shape of guide cable is the most unfavorable in the starting condition, the original length should not be too long and should not exceed the original length of the main cable; (2) the change of cable force of guide cable and traction cable is subject to the original length of guide cable. The influence is large and sensitive; (3) the original length of the guide cable should be between the original length of the main cable and the distance between the two ends. According to the calculation results, according to the calculation results, the construction parameters needed in the actual construction are obtained, including the non stress length and tension of the guide cable, pulling force and so on. This paper is based on the anchorage position of the lower end of the cat track in the guide cable and the extended part of the mounting area along the guide cable, and it is true that the construction site is true. The arrangement position of the independent tower is fixed. Through the analysis of the construction process of the traction and installation area and the expansion part of the guide cable, the force of the anchor and the cable to the anchorage point is obtained. According to the size and direction of the force, the structure of the independent tower is connected by a single plane truss to increase the structure integrity, and the small tower is set by the back cable. According to the construction process, the multi group load combination is set, the construction process of the tower is analyzed and a set of practical construction scheme is determined. As a high-precision astronomical telescope, the fabrication and installation accuracy of the FAST cable net support structure are very high, so the precision control is very important. The error sensitivity analysis is carried out on the cable net structure, the error factor and the degree of sensitivity are determined, and the precision of the construction is combined with the actual construction. The control index of the construction precision is determined, which provides the basis for the precision control of the cable network construction.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU758.11

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