为解决软弱富水地层四线大断面隧道近距离下穿大型综合管廊的支护及沉降控制技术难题，以广佛城际下穿华康道管廊工程为例，通过案例调研、方案比选、数值模拟分析及现场监测的方法，对超前加固方案、暗挖支护参数、施工工法、施工工艺等开展研究。研究结果表明： 1）管廊底部设置托底管棚+隧道拱部超前管棚+水平旋喷止水预加固+双层衬砌的协同支护方案在工程适应性、工期及造价方面最优。2）4管隧道采用①—③—②—④顺序开挖，①、③、④号隧道采用CRD法，②号隧道采用三台阶法对隧道沉降及管廊沉降控制最优。3）①号隧道开挖时隧道及管廊沉降变形速率最大。4）地表、管线、管廊及拱顶沉降变形均在5 mm内。
Technical issues include support and settlement
control induced by the fourtrack large crosssection tunnel closely crossing beneath the large utility tunnel in
weak and waterrich strata are always encountered. As a
result, case investigation, scheme comparison and selection, numerical
simulation analysis, and onsite monitoring methods are
used to investigate the construction technologies and processes, advanced
reinforcement, and supporting parameters of the GuangzhouFoshan intercity passing beneath the Huakang road utility tunnel.
The results reveal the following: (1) Based on the active deformation control
technology, the collaborative support scheme of the pipe roof under utility
tunnel, advanced pipe roof at the tunnel arch, horizontal jet pregrouting and
waterproofing, and doublelayer lining are adopted,
which is the optimal in terms of adaptability, construction period, and cost.
(2) The fourtube tunnel is excavated in order of
numbers 1, 3, 2, and 4. The cross diaphragm method is used for tunnel numbers
1, 3, and 4, whereas the threebench method is used for
tunnel number 2 to control the settlement of the tunnel and the utility tunnel.
(3) During the excavation of the tunnel number 1, the settlement and deformation
rate of the tunnel and utility tunnel is the largest. (4) Onsite monitoring results show that the settlements of surface,
pipeline, utility tunnel, and tunnel crown are all within 5 mm.
