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介绍了隧道锚原位缩尺模型试验两种施力方法的原理及方法,剖析了不同施力方式对缩尺模型锚试验的影响。缩尺后模型尺寸变小,前拉法的散索难以可靠实施,直接影响拉拨效果,同时,拉拨中需要设置巨大的反力梁,不仅大大增加试验成本,而且对围岩变形测量影响大。为此研究了一种替代方法——后推法。以实例为基础剖析了前拉法的优缺点,介绍了后推法的原理、方法及实施要点,并以重庆几江长江大桥为例,采用有限差分法对模型锚不同施力方式作用后的塑性区分布、变形特征及破坏特征进行了比较分析,两种施力方法作用于模型锚后的塑性区分布和变形分布上有细微差别,通过重庆几江长江大桥1∶10缩尺模型试验验证,其破坏模式基本吻合,表明后推法可以替代前拉法。目前该方法得到了推广应用。
The principle and method of two kinds of application methods of tunnel anchor in-situ scale model test are introduced. The influence of different application methods on the anchor test of scale model is analyzed. After scaling, the size of the model becomes smaller, and the random number of the former pull method can not be reliably implemented, which directly affects the pull-pull effect. Meanwhile, the huge reaction force beam needs to be set in the pull-pull, which not only greatly increases the test cost but also affects the deformation measurement of the surrounding rock Big. To this end, we study an alternative method - backstepping. The advantages and disadvantages of pre-pull method are analyzed based on examples. The principle, method and key points of post-push method are introduced. Taking Chongqing Ji Jiang Changjiang River Bridge as an example, the finite difference method Plastic zone distribution, deformation characteristics and failure characteristics were compared and analyzed. The plastic zone distribution and deformation distribution of the two anchoring methods were numerically different from each other. Through the 1:10 scale model test of Chongqing Jingjiang Yangtze River Bridge, , The destruction mode is basically consistent, suggesting that the pushback method can replace the former Rafah. At present, the method has been popularized and applied.