盾构穿越花岗岩球状风化孤石群的施工关键技术

为解决盾构穿越孤石群地层的难题,对花岗岩风化孤石的形成机制及盾构穿越孤石群产生的地面沉降、姿态控制、设备安全的风险进行研究,并分析传统孤石处理方法在孤石群地层中运用的局限性。主要结论如下:1)盾构穿越孤石群施工应系统考虑孤石预处理、掘进和开舱换刀方案;2)采用地下隐蔽岩体爆破技术对孤石进行爆破破碎后能降低盾构掘进风险,并且盾构通过期间须严格控制掘进参数;3)采用压密注浆改良刀盘周边地层,盾尾止水和舱内制作泥膜措施辅助带压进舱,能提高开舱成功率,解决刀具更换的问题。

Key Technologies for Shield Boring through Ground Containing Weathered Spherical Granite Boulder Groups

The running tunnel from Luogang station to Xiangxue station on Line 6 of Guangzhou Metro crosses ground containing boulder groups, therefore the shield has great risks in the boring of the running tunnel. In the paper, the forming mechanism of the weathered granite boulders is presented, the ground surface settlement, shield attitude control and equipment risks are studied, and the limitations of the conventional boulder treatment methods are analyzed. Conclusions drawn are as follows: 1) Systematic scheme including boulder pretreatment, shield boring and cutter replacement should be considered when shield bores through ground containing boulder groups; 2) Preblasting the underground boulders on the tunnel route can reduce the risks of shield boring, and the shield boring parameters must be strictly controlled when the shield bores through the ground containing boulders; 3) The consolidation of the ground around the cutterhead by means of compaction grouting, water sealing at the shield tail and forming filter membranes in the chamber are helpful to the cutter replacement under hyperbaric conditions. 