洋流作用下悬浮隧道动力学行为试验研究

Experimental Study of Dynamic Behavior of Submerged Floating Tunnel under Current Effect

为测试悬浮隧道在洋流作用下的动力学行为,根据流场相似准则和弹性相似准则以及试验条件恰当地进行模型试验设计。考虑到实际流场洋流方向的不确定性,以圆形截面悬浮隧道进行试验,通过测试洋流作用下悬浮隧道管段的应变情况获得悬浮隧道的力学行为。试验模拟测试了在各种不同流速条件下,单节悬浮隧道管段在分别布置2组锚索支撑和布置3组锚索支撑时,悬浮隧道管体结构环向应变和轴向应变及张力腿锚索的轴力。试验表明:(1)管段外侧环向应变较内侧大,内外侧轴向应变相差不大;迎流面环向应变较背流面大,迎流面轴向应变较背流面小;外侧顶面环向应变与底面环向应变相差不大,外侧顶面轴向应变与底面轴向应变也相差不大;(2)增加支撑锚索数量能减小管段结构和锚索的受力;随着流速增加,管段上相同测点的轴向应变、环向应变都随流速的增大呈线性关系变化;(3)管段相同侧锚索轴力随时间的变化趋势基本一致,但受力变化并不均匀,迎流面侧锚索所受拉力随流速增大而线性增大,背流面位置处锚索所受拉力随流速增大呈线性减小后变为压力。

In order to obtain the dynamic behavior of the submerged floating tunnel under the current effect, the model experiment was designed rightly according to the current similarity criterion, the elastic similarity criterion and the experiment conditions. Considered that the realistic current orientation is always random, the submerged floating tunnel with circular cross-section was used in the test. The dynamic behavior of submerged floating tunnel was acquired by testing the tube＇s strains under the current effect. The model experiment was conducted to test the annular strain, the axial strain, and the axial force of the tension leg anchor of the submerged floating tunnel structure under the conditions of different current velocities and one tube segment of submerged floating tunnel supported by two sets and/or three sets of anchor support. The result of experiment shows that （1） The outer annual strain of the tube is larger than that of the inner one, however, the outer axial strain of the tube is the same as that of the inner one. The up-stream annual strain is larger than that of the back one, but the axial strain has the opposite trend. There is little difference between the outer annual strain on the top and that at the bottom, and the outer axial strain has the same tendency. （2） With the number of support cable increasing, the force effected on the tube or the cable can be decreased. With the velocity of the current increasing, either the axial strain or the annular strain in the same position changes linearly. （3） There is the same tendency of the axial forces of the cables in the same side change with time, but the forces change unevenly. With the current velocity increasing, the tension of the cable faced to the stream increases linearly, while the tension of the cable back to stream increases and then linearly decreases and it becomes pressure at last.