沉管隧道混凝土管节与碎石基床摩阻力原型观测与试验

Full scale observation and test of the frictional force of the concrete element and gravel bed of immersed tunnel

尽管在沉管隧道使用后铺基床的案例在增加,国内外文献未见对沉管管节与基床的摩阻力的试验或观测,而该系数是沉管隧道设计与施工的关键参数。文章报告港珠澳大桥33节沉管管节水下拉合作业的摩阻力的观测。观测数据有三个来源,管节原型拉合作业与纠偏作业,小尺寸模型试验,以及最终接头永久焊接过程的相邻管节的运动。内容包括混凝土与碎石,混凝土与淤泥,以及混凝土与砂基床的摩阻力。试验分析了碎石粒径、压力、方向、面积等因素对摩擦系数的敏感性。并且,对管节拉合过程中的实际摩阻力以及摩擦系数进行了观测与统计。

There is an increasing tendency of using pre-placed foundation layer in immersed tunnel construction,however the test or site measurement of the friction coefficient of this layer and the immersed tunnel element,which was an important input parameter both for design and construction,was missing in literature. The paper reported the observations and study of the friction forces for the 33 immersed tunnel elements underwater pulling operation. The data were from three sources,the element pulling operation and re-alignment( i. e. full scale),the small-scaled test,and the movement of the adjacent element during the permanent welding works of the closure joint. The test contents are the friction of concrete and gravel,concrete and sediment,and concrete and sand. Sensitivity analysis were made to influential factors such as gravel size,pressure,direction and area against friction coefficient;From element pulling operation,the average value and the maximum value of the frictional force are calculated and summarised.