海河隧道工程防洪影响分析

Analysis on impact from Haihe River Crossing Tunnel Project on flood control

海河隧道线路全长2 303.4 m,其中主河道沉管段长240 m,沉管断面宽度37.4 m,高9.8 m,共设置两节,每节120 m。河道沉管段采用水中沉管法施工。管段安装会对河道的防洪安全产生较大的影响,故须对河段的水沙条件有严格的要求。本文采用三维分层水流泥沙数学模型,通过错层处理,较好地解决了同层网格产生急剧变化,在突变点处隔层网格物理量的影响远大于层间网格的影响问题。对隧道管段悬浮状态、沉放过程中的过流能力、水流流态和河段水流泥沙运移规律进行了深入分析,提出管段对河段水沙的影响程度及解决措施。本研究拓展了三维分层水流泥沙数学模型的应用范围,为保证工程施工安全提供了理论基础。

The total length of Haihe River Crossing Tunnel is 2 303.4 m,of which the main river channel crossing section consisted of the immersed tube is 240 m long with a width of 37.4 m and a height of 9.8 m and is divided into two segments with each of 120 m long.The river channel crossing section of the immersed tube is constructed with the immersed tube method.As a larger impact will occur from the installation on the flood control and safety of the river channel,a strict requirement must be made on the water and sediment condition of the corresponding river section.With the introduction of the 3-D layered water-sediment numerical model,the problem of that the mutation occurs in the grids of identical layer and the impact from the physical quantity of the interlayer grids at the catastrophe point is much larger than that from the layered grids is effectively solved herein through the treatment of staggered layers.Furthermore,the discharge capacity,flow regime and water-sediment transport law of the river section during the suspension and sinking of the tunnel tube segments are deeply analyzed,and then the degree of the impact from the tube segment on the water and sediment condition therein and the relevant solving measures are put forward as well.This study extends the application area of the 3-D layered water-sediment numerical model and lays a theoretical basis for ensuring the construction of the project concerned.