孟加拉卡纳普里河水下隧道工程具有近海域、大潮差、大坡度、大直径、穿越富水粉细砂地层等特点,盾构始发涌水、涌砂风险 极高。为有效减小盾构始发穿越富水砂层的突涌问题,采用大直径气垫式泥水加压平衡盾构设备,从加固松软地层、切断地下水来 源和减轻突涌后果3 方面入手,提出三重管旋喷桩加固技术、降水技术和大直径钢套筒始发技术。大直径钢套筒始发技术包括大 直径钢套筒及支撑体系设计与安装技术、大型钢套筒及反力架变形监测技术、钢套筒内始发泥水建仓技术。钢套筒密封代替常规 帘布橡胶洞门密封装置,变局部密封为整体密封,大幅度降低了盾构进入富水粉细砂层时洞门涌水、涌砂的风险,提高了盾构始发 的安全性。

The Karnaphuli River-crossing Tunnel project in Bangladesh has the characteristics of nearby sea area, spring tide difference, large slope, large diameter and crossing through water-rich sandy stratum. The risk of water and sand gushing is very high. Hence, to solve the water and sand gushing problem during shield launching, the large-diameter air cushion type slurry pressure balanced shield is adopted. The reinforcement technology of triple-pipe jet grouting pile, dewatering technology and large-diameter steel sleeve launching technology are put forward from the aspects of strengthening the soft stratum, cutting off the source of groundwater and reducing the consequence of water and sand gushing. The large-diameter steel sleeve launching technology includes large-diameter steel sleeve and support system design and installation technology, large steel sleeve and reaction frame deformation monitoring technology and technology of establishing slurry chamber in steel sleeve. The conventional curtain rubber hole sealing device is replaced by steel sleeve seal, and the partial seal is changed into the whole seal, which greatly reduces the risk of water and sand gushing in the hole in water-rich sandy stratum and improves the safety of shield launching.