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利用足尺砂流法模型试验模拟了砂流法处理沉管隧道地基施工致使管节竖向位移的全过程,获得了管节模型的相对高程-时程曲线、竖向位移量及砂盘的形态特征。结果表明:模型在试验中先后经历了砂盘正常扩展、缓慢跳动位移、快速平稳位移3个阶段;模型在缓慢跳动位移过程中的位移量、位移速率均较快速平稳位移过程中的要小。模型板的竖向位移使得流缝区域缩小,流槽厚度变薄且密集分布于砂盘顶面(占砂盘顶面积的30%以上);砂颗粒压积于砂盘顶部形成水平薄层状结构,是模型板竖向位移的直接原因;模型板竖向位移过程明显影响砂盘的半径扩展。工程实践中可适当利用管节的缓慢跳动位移过程减小流缝、流槽厚度,但需采取措施保证砂盘半径在管节产生竖向位移前达到设计值。
The full-scale sand flow method was used to simulate the whole process of vertical displacement of pipe joints caused by sand flow method in sand tunnel construction. The relative elevation of pipe joint model-time history curve, the vertical displacement and the morphological characteristics . The results show that the model has experienced three stages of normal expansion, slow bouncing displacement and fast and steady displacement in the experiment. The displacement and displacement velocity of the model are both smaller and faster in the course of slow bouncing displacement. The vertical displacement of the model plate causes the area of the flow gap to narrow, and the flow channel thickness becomes thinner and densely distributed on the top surface of the sand plate (accounting for more than 30% of the top area of the sand plate); sand particles are pressure-packed on the top of the sand plate to form a horizontal thin layer The structure is the direct cause of the vertical displacement of the model plate. The vertical displacement of the model plate obviously affects the radial expansion of the sand plate. The engineering practice can make proper use of the slow bouncing displacement process of pipe joints to reduce the thickness of flow slots and gutters, but measures must be taken to ensure that the disc radius reaches the designed value before the vertical displacement of pipe joints occurs.