近年来我国在冲淤剧烈的江河感潮段建设了大量的水下盾构隧道，然而目前就水位波动和冲淤作用对盾构隧道土水压力的影响尚缺乏深入认识。本项目拟采用试验与理论相结合的方法，研究在水位波动和河床冲淤作用下盾构隧道土水压力的作用机理。首先，通过物理模型试验模拟多种工况，分析盾构隧道土水压力的分布模式、变化规律及主要影响因素。其次，进行水力连通试验，揭示隧道渗漏水过程中水体的运移路径，探究隧道水压力与河水水位、地基条件及隧道透水状况等参数的定量关系。之后，基于试验结果和基本理论，开展理论分析和数值模拟，研究隧道与土体的相互作用模式以及考虑隧道渗漏的隧道水压力响应；同时，使用正交试验法确定地基抗力系数及侧向土压力系数等关键设计参数的取值。最终提出考虑水位波动和河床冲淤作用的盾构隧道土水压力计算方法。研究成果有望为复杂水力环境下冲淤河段盾构隧道的设计、施工及运营维护提供科学依据和理论指导。

Nowadays a large number of shield-driven tunnels have been constructed beneath rivers which are distinguished for tidal bores and riverbed scour-deposition. However, the study on soil and water pressure on shield-driven tunnels influenced by river stage fluctuations and riverbed scour-deposition is still superficial. Experiments combined with theoretical analysis are conducted to study action mechanism of soil and water pressure on shield-driven tunnels subject to river stage fluctuations and riverbed scour-deposition in this project. First of all, many different working conditions are simulated in the physical model experiments to study the distribution model and variation tendency of soil and water pressure on tunnels, and identify its primary influencing factors. Secondly, the hydraulic conductivity test is conducted to reveal water seepage path during tunnel leakage, and explore the quantitative relations between water pressure on tunnels and their working conditions, including river stage, ground conditions and tunnel drainage conditions. Afterwards, theoretical analysis and numerical simulations are implemented based on the experimental results and the basic theories to study the interaction between tunnel and soil and the response of water pressure with account of tunnel leakage. In the meanwhile, the orthogonal test method is applied for the determination of coefficients that are critical to tunnel lining design, such as the coefficient of subgrade reaction and the coefficient of lateral earth pressure. Finally, a calculation method is put forward to calculate soil and water pressure on shield-driven tunnels taking the impacts of river stage fluctuations and riverbed scour-deposition into account. The results are expected to provide reliable scientific basis and theoretical guidance for construction, design and maintenance of underwater shield-driven tunnels in riverbed subject to complex hydraulic conditions and scour-deposition.