为进一步提高隧道防水的可靠性，特别是针对超大水深和沿线地质条件变化较大情况下建设水下隧道的需要，对现有的沉管隧道和盾构隧道结构及施工技术进行对比分析，采取提炼基本技术元素加以创新组合的方法，提出全新的先导管盾构隧道构想及其施工方法和施工用水盾构。以在水底铺设的管道作为先导管和防水结构，在管道内推进盾构进行排水，创造干施工条件进行隧道管片拼装；然后压力注浆填充间隙，使先导管和隧道管片形成整体，构成隧道主体结构。这种隧道的构筑方法和专利技术对地质条件要求低，能适应较大的水头压力，且具有较好的防水可靠性，同时顺应建筑工程产业化的技术发展趋势，为提高建筑装配化率和构件标准化水平提供了空间，有望在不久的将来成为新的主流技术。经济指标对比分析结果表明： 1）先导管盾构隧道防水结构费用占比增加； 2）相较盾构隧道，盾构推进挖土费用大幅减少； 3）相较沉管隧道，主体钢筋混凝土费用和主体结构总费用均大幅减少，具有一定的经济优势。
To further improve the waterproof capability of
underwater tunnels with superdeep water and various geological
conditions, comparison is made between immersed and shield tunnels based on
existing structures and construction technologies. A new type of watershield machine and relevant tunneling technology (guidedshield tunneling) are proposed based on basic technical element
extraction and innovation methods. For the guidedshieldtunneling method, guided tubes are laid in advance as waterproof
structures. Subsequently, the water shield tunnels in the tubes to drain, thus
creating a dry environment to conduct segment erection. Finally, pressurized
grouting is employed to fill the gaps, thus integrating the guided tubes and
tunnel segments to form the main tunnel structures. This method has many
advantages, including low requirements on ground conditions, adaptability to
various waterhead pressures, and good waterproof performance. Thus, this method
improves assembly construction rate and the standardization level of
components, making it a potential mainstream technique in underwater tunneling.
The comparative results of economic indexes show that: (1) the cost of
waterproof structures requires a greater portion of the total cost of the
guidedshieldtunneling method
than that in the shield or immersed tunneling method; (2) the cost of soil
excavation in the guidedshield tunneling method is
much less than that in the shield method; (3) the cost of concrete and main
structures in the guidedshield tunneling method is
much less than that in the immersed tunneling method; thus, the guidedshield tunneling method has good economic benefits.
