串联拉索沿导索空中累积滑移安装方法及过程分析

Installation method and construction process analysis of accumulative sliding along guide cable of serial cables at high altitude

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,利用牵引索将结构索由下至上沿导索累积牵引就位。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悬垂拉索、机构大位移和在导索上的滚动滑移。其过程分析,基于非线性动力有限元分析法找形,根据导索单元组总无应力长度(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,并提出了一致初应变、模型长度倍增、逐单元递推和逐单元递推倍增等4种策略且进行了对比,结果表明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、端点直线距离和中间值,通过对比指出了关键施工参数的变化规律,结果表明: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;导索和牵引索的索力变化受导索原长影响大,且较为敏感;合理的导索原长应介于主索原长和两端直线距离之间。

The installation method of accumulative sliding of serial cables at high altitude based on the feature of cablenet structures was proposed. During the process,the serial cables are connected with guide cable by booms or chain hoists,and then are pulled upwards to its design place accumulatively by pulling cable. This method could make full use of the guiding function and the loading-bearing capacity of guide cable,while it＇s simple and cheap to operate.During the pulling process,cable slackness and mechanism displacement may occur. Based on the nonlinear dynamic finite element method（ NDFEM）,and according to the principle of constant total original length of guide-cable elements,the original length of guide-cable elements was adjust respectively to simulate the movement of pulleys on the guide cable. Furthermore,four strategies to adjust the original length of guide-cable elements,which were ‘same initial strain＇,‘model length multiplication＇,‘piecewise recursion＇and ‘piecewise recursion and multiplication＇strategies,were proposed and compared. It is concluded that the ‘piecewise recursion and multiplication＇strategy is the best in analysis efficiency. The guide-cable original length was set respectively as the total main-cable original length,linear length to endpoints and intermediate values of the above two,and the changing regulations of key construction parameters were contrasted. It is concluded that the guide-cable configuration is the most unfavorable at the initial accumulative sliding stage,and the guide-cable original length should not exceed the main-cable origin length; the force of guide cable and pulling cable is sensitive to the guide-cable original length; the reasonable original length of guide cable should be between the main-cable original length and the linear distance between two ends.