内河交汇处沉管隧道基槽回淤厚度研究

基槽回淤对沉管隧道平顺度影响较大,对其防水性能产生威胁。为研究两河交汇处沉管隧道基槽的回淤特性,依托如意坊沉管隧道,构建数值计算模型,对比实际监测值以验证模型的适用性,进而揭示内河交汇处沉管隧道基槽回淤规律。研究结果表明:模型中河流流速与实际监测数据误差较小,验证了模型的适用性;内河交汇处基槽淤积厚度整体呈中间大两端小、上游大下游小的规律;回淤分布受空间影响较大,基槽底脚淤积显著,且坡顶淤积厚度显著小于坡底;回淤量随时间的延长其敏感性逐渐下降;基槽开挖后,回淤均值为10 cm,将影响沉管隧道的施作,现场须采取清淤措施进行处置。研究成果为两河交汇处沉管隧道基槽回淤分析与治理提供了指导。

Silt Characteristics of Immersed Tube Tunnel Foundation Trench at Inland River Intersection

The siltation of foundation trench has severe impact on the smoothness of immersed tube tunnel and threatens its waterproof performance.The silt characteristics of immersed tunnel foundation trench at the intersection of two rivers are researched by establishing a numerical calculation model.The simulation result is compared with actual monitoring value to verify the applicability of the model,and furthermore to reveal the siltation characteristics of immersed tunnel foundation trench at inland river intersection.Results display small error between the simulated flow velocity and the actual monitored value,verifying that the model is applicable.The silt depth is large in the middle and small in two ends,and large in the upstream while small in the downstream.The siltation varies largely in space,distributing apparently at the trench foot and remarkably on slope crest than at slope toe.The sensitivity of siltation attenuates gradually over time.After the excavation of foundation trench,the silt depth reached 10 cm,which would affect the application of the immersed tunnel.Dredging measures on site are required.