针对山地城市环境下过江隧道建设面临的地形高差悬殊、地质复杂、城市建筑密集等挑战，以渝湘高铁重庆长江隧道为依托，结合工程地形地貌、水文地质及城市环境特征，通过多维度技术比选与创新设计，对线路敷设方案、隧道分合修、盾构选型、施工组织方案、运营排水、养护通风等开展系统研究，形成适应于山地城市特点的过江隧道关键技术集成体系。研究表明： 1）采用泥水平衡盾构可有效应对0.9 MPa高水压及砂岩-泥岩互层地质条件，避免喷涌风险并提升掘进效率； 2）施工工艺上首次提出盾构洞内组装始发及接收拆解技术，利用85 m长组装洞和40 m长拆解洞完成盾构洞内的始发与接收，规避了传统超深竖井方案施工风险高、城市干扰大的难题； 3）隧道断面采用蘑菇形结构，通过多分部开挖与肋板式锚杆挡墙叠合支护，确保了613 m2超大断面隧洞的稳定施工； 4）提出分段运营排水系统与轨下廊道通风方案，结合泥浆航运弃渣模式，解决了高水压渗流与城区环保难题。工程实践表明，上述技术集成体系显著降低了山地城市环境下过江隧道的施工风险与城市影响，提升了隧道建设质量与效率。
River-crossing tunnels in mountainous cities face numerous challenges,
including significant terrain elevation differences, complex geological conditions,
and densely built urban environments. The authors examine the Yangtze river
tunnel of the Chongqing-Hunan high-speed railway in Chongqing, China, focusing on the project′s topography, hydrogeology, and surrounding urban setting. A
multidimensional technical comparison and innovative design process are
undertaken to optimize the route alignment, excavation scheme, shield type
selection, construction organization, operational drainage, maintenance, and
ventilation. As a result, a key technological integration system is developed
for river-crossing tunnels in mountainous cities. The
findings are as follows: (1) The slurry balance shield effectively accommodates
geological conditions of 0.9 MPa high water pressure and sandstone-mudstone interbedding, thereby preventing water and mud inrush and
enhancing tunneling efficiency. (2) In-tunnel shield
assembly and disassembly are implemented using launch and reception tunnels
with diameters of 8.5 m and 4.0 m, respectively, successfully mitigating the
risks associated with conventional ultra-deep shaft
construction and reducing urban disruption. (3) A mushroom-shaped cross-section with an ultra-large area of 613 m2 is adopted, and multi-section stepped excavation with composite support using rib-plate-anchor retaining walls ensures
construction stability. (4) A segmented operational drainage system and an
under-rail corridor ventilation layout are established,
and slurry transport is conducted via shipping, addressing challenges related
to high water pressure, seepage, and environmental protection in urban areas.
Engineering practice confirms that the proposed integrated technology system
effectively reduces construction risks and urban impact while improving the
quality and efficiency of tunnel construction in mountainous city environments.
