【作者】 杜朝伟；

【导师】 王梦恕； 谭忠盛；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2011， 博士

【摘要】 海底隧道渗流量和衬砌后水压力是海底隧道设计者关心的主要问题,本文在深入分析现有研究成果的基础上,以厦门海底隧道为工程背景,综合运用理论分析、数值计算、模型试验和现场监测等方法,对海底隧道衬砌后水压力分布和结构受力特征进行了系统研究。主要研究工作如下：(1)基于地下水水力学理论和复变函数方法,建立了海底隧道渗流场分析的解析模型,推导了均质围岩中海底隧道涌水量和水压力分布的解析公式。以厦门海底隧道F4全强风化囊为工程背景,对海底隧道渗流场进行了分析。结果表明,注浆圈和初期支护的渗透系数和注浆厚度对衬砌后水压力和渗流量影响较大,随着排水系统部分阻塞,衬砌后的水压力随隧道的排水量减少而增大。在堵水限排情况下,通过加强注浆等工程措施,初期支护承受的水压力可按照静水头的1/3考虑。(2)研发了可同时施加水压力和土压力的加载系统和模型试验台架,基于模型试验相似理论,推导了相似准则,设计了应力场和渗流场共同作用下的海底隧道模型试验。以厦门海底隧道为工程背景,在模型试验台架上进行了1：38.8的水土压共同作用下的海底隧道模型试验。在模型试验首次应用了光纤光栅传感器。(3)通过模型试验测试了隧道在全封堵方式和限排方式中的水压力分布规律及衬砌结构受力特征。结果表明,全封堵情况下,衬砌须承受全部静水压力,不能折减。在限制排放的情况下,排水系统对衬砌背后的水压力分布和大小影响很大,衬砌背后的水压力和隧道控制排水量成反比例线性关系,距离排水口越近,水压力折减效果越明显。在渗流场和应力场的共同作用下,衬砌结构的应力随着排水量的增大而减小,衬砌的最不利部位为仰拱内表面,水压力是结构承受的主要荷载。(4)通过模型试验研究了防水板半包和全包对衬砌水压力和结构受力特征的影响。研究结果表明,全封堵条件下,防水板全包、半包对衬砌背后的水压力、结构的受力无明显影响。在排水方式下,防水板半包可以使结构受力更加均匀,并能对结构的局部受力起到优化的作用。鉴于海底隧道衬砌水压力为主要荷载,海底隧道应采取防水板半包的防水方式。(5)运用模型试验和数值分析方法研究了厦门海底隧道渗流场,对厦门海底隧道F4风化囊进行了流固耦合数值分析,在堵水限排情况下,通过加强注浆等工程措施,一次衬砌具有较好的安全性。(6)推荐了厦门海底隧道防排水系统。厦门海底隧道采用堵水限排的防排水原则,防水板采用半包式,施工期间初期支护承受全部土压力及约1/3的水压力。提出了厦门海底隧道的渗流量控制标准,厦门海底隧道软弱围岩地段的渗流量应按照0.25m3/(m.d)控制。对施工现场的围岩压力、一次衬砌后水压力和钢拱架内力进行监测,得出了施工过程中水压力、围岩压力随开挖过程的变化规律,止水注浆和初期支护后回填注浆是减小衬砌后水压力的重要措施。以上研究基本上阐明了海底隧道衬砌水压力确定这一困扰工程界的问题。本文的部分研究成果直接应用到了厦门海底隧道工程。更多还原

【Abstract】 Water inflow and water pressure at the lining back of the subsea tunnel is the main problem that the designer of subsea tunnel cares for. Based on thorough analysis of existing research achievements, using model test combined with theoretical analysis, spot test and measure and numerical calculation, the distribution of water pressure at lining back and the stress characteristics of lining structure of subsea tunnel are systematic studied in this thesis. The main research work is as follows:(1)Based on groundwater mechanics and complex variable methods, the analytical model of the subsea tunnel seepage field is established and the analytical formula for water inflow and water pressure distribution of subsea tunnel in uniform rock are derived. Using the F4 entire strong weathering bursa of Xiamen subsea tunnel as engineering background, the seepage field of subsea tunnel is analyzed. The result shows that the permeability coefficient and thickness of the grouted ring and primary support have great influence on the water pressure at lining back and water inflow. In case of the drainage system blocking up, the water pressure on primary support increases with the actual water inflow decreasing in the construction period. In case of controlled drainage, by strengthening some measures such as grouting, the water pressure on primary support can be reduced to 1/3 of the full hydrostatic pore pressure.(2) Invent the model test framework and loading system which can add rock-mass pressure and water pressure at the same time is invented. Based on similar theory of model test, similar criterion is derived. The model test of subsea tunnel in stress field and seepage field is carried out on the test framework whose prototype is Xiamen subsea tunnel. The similarity scale of the model and prototype is 1:38.8. In the model test the Brag optical fiber sensors are firstly adopted(3)The model test result shows that in case of entire plugging the lining must support the full hydrostatic pore pressure and the water pressure can not be discounted. In case of limited drainage, the drainage system has a great influence on water pressure at lining back. Water pressure at lining back has an inverse liner proportion to the controlling water inflow of the subsea tunnel. The effect of water pressure discount is more obvious when the test point is closer to the drainage hole. In seepage field together with stress field, the stress of the liner structure decreases with the drainage increases. The most unfavorable part of the tunnel structure is the inner surface of the invert.. The water pressure is the main load that the tunnel structure sustains. (4) The lining water pressure distribution and the strain of the lining have been studied with different proof-drainage patterns:half covered waterproof board and whole covered waterproof board through model test. The research reveals that the lining water pressure does not be influenced much when covered waterproof board changed from fully covered to half covered. In circumstance of drainage, when the half covered waterproof board style is adopted, the stress distribution of the stress on the lining will be more equitable and even, and the stress concentration on near the invert will be improved. In consideration of that the water pressure is the main load that the tunnel structure sustains, the water proof style of half covered waterproof board should be widely adopted in subsea tunnel.(5)By model test and numerical calculation method the seepage field of Xiamen subsea tunnel is studied. Stress-seepage coupled numerical analysis is carried out to the F4 entire strong weathering bursa of Xiamen subsea tunnel. The emphasis of research is put on the security of the primary support in the construction period. The result shows that by strengthening some measures such as grouting, the primary support has a high security coefficient.(6)The waterproof and drainage system of Xiamen subsea tunnel is recommended Xiamen subsea tunnel adopt the principle of controlled drainage to deal with groundwater. The waterproof layer is half-pack style. The primary support supports the load in the construction period which is 1/3 of the full hydrostatic pore pressure and all the surrounding rock-mass pressure. The water inflow controlling criteria of Xiamen subsea tunnel is put forward. The water inflow in soft rock section in Xiamen Subsea Tunnel Should be less than 0.25m3/m. The surrounding rock-mass pressure, water pressure behind the primary support and the stress of steel arching supporter is measured on the construction spot. The changing law of water pressure and rock pressure along with excavation in the construction period is obtained. Backfill grouting at the back of primary suppot and waterproof grouting are the important measure to reduce the water pressure on the lining in subsea tunnel.The above research has expounded the problem of water pressure at lining back by the large. Part of the research achievement has been directly applied in Xiamen subsea tunnel project.更多还原