考虑管土效应的潮汐荷载引起沉管隧道管节沉降研究

Research on settlement of immersed tunnel elements under tidal load with consideration of element-soil effect

利用三角函数拟合潮汐荷载,计算潮汐荷载作用下河床土层的一维非线性固结沉降。基于Winkler地基模型,依据潮汐荷载和土层沉降反算不同时刻的等效基床系数。考虑接头作用,建立管节-接头计算模型,分析潮汐影响下的沉管隧道管节竖向位移。依托宁波甬江沉管隧道工程,计算管节中点和接头竖向位移随潮位的变化,并将理论计算结果与实测结果进行对比分析。研究结果表明:J2接头截面竖向位移计算变化量与实测变化量较为吻合,表明本文提出的理论计算方法合理;潮汐影响下甬江隧道沉管段的浮动范围为4~8mm,最大浮动量出现在E3管节中点截面,其中日浮动量和年浮动量分别达到6.9和7.4mm;同一管节截面的年浮动量稍大于日浮动量,且呈现正相关性;同一管节中,中点浮动量大于接头浮动量,而不同管节的同一位置截面中,越靠近隧道中点的浮动量越大。

Tidal load is fitted by trigonometric function,and One-dimensional nonlinear consolidation settlement of layered soils is calculated under tidal load. Based on the tidal load and the result of subsurface settlement,Winkler foundation model is used to calculated equivalent subgrade coefficient at different time. Considering the effect of joint,an element-joint model is built to analyze the vertical displacement of immersed tunnel elements under tidal load. Rely on Yongjiang Immersed Tunnel in Ningbo,the vertical displacement of joints and the midpoint of the elements is calculated under tidal load,and the theoretical results are compared with the measured results. The study shows that the calculated vertical displacements of Joint 2 are consistent with the monitoring data. It provides validation of the proposed method. The range of vertical displacement amplitude of Yongjiang Immersed Tunnel's elements is 4–8 mm under tidal load. The maximum displacement amplitude is present to the midpoint of Element 3. The displacement amplitude of Element 3 in a day and in a year reaches 6.9 mm and 7.4 mm respectively. As for one section of an element,its displacement amplitude in a day is slightly larger than that in a year,and they are positively correlated in different sections. As for one element,its displacement amplitude of midpoint is larger than that of joints. As for the same position of different elements,the closer to the midpoint of tunnel the section is,the lager the displacement amplitude is.