Application and evaluation of ground surface pre-grouting reinforcement for 800-m-deep underground opening through large fault zones
Application and evaluation of ground surface pre-grouting reinforcement for 800-m-deep underground opening through large fault zones
复制标题
穿越大断裂带800米深地下洞室地表预注浆加固应用与评价
DOI：
10.1007/s12517-017-3052-7
复制
发表时间：
2017
影响因子：
--
通讯作者：
Zhang Nianchao
中科院分区：
文献类型：
--
作者：
Qian Deyu;Zhang Nong;Zhang Mingwei;Shimada Hideki;Cao Peng;Chen Yanlong;Wen Kai;Yang Sen;Zhang Nianchao
断层是地下工程开挖过程中经常遇到的复杂地质条件。在华东某大型断裂带800 m深地下洞室的先导性开挖中，采用了单导坑法、30 m钻孔预注浆等多种支护方案。然而，突水、泥石流、冒顶等地质灾害仍时有发生，严重威胁着隧道施工安全。为消除地质灾害，确保隧道施工安全，首次提出并实施了地表预注浆（GSPG）加固穿越大断层带的800 m深地下洞室区域工程岩体。基于水力劈裂理论，提出了地表以下800 m处GSPG的最小灌浆压力，为GSPG工程实践提供了有价值的指导。工程实践表明，GSPG消除了地质灾害，提高了目标岩体的稳定性，确保了隧道施工安全。现场实测结果表明，GSPG作用下围岩位移速度呈现明显的波动响应，GSPG对800 m深地下洞室稳定性的影响随距注浆孔距离的增大而显著减小。最大变形速度与距注浆孔的距离呈指数负相关。此外，GSPG期间的地下安全距离大于137 m。
Faults are complex geological conditions that are commonly encountered during underground excavation. Many support schemes, such as using a single pilot heading method and 30-m-long borehole pre-grouting, have been implemented during the pilot excavation of an 800-m-deep underground opening that passes through large fault zones in East China. However, various geo-hazards, including groundwater inrush, debris flow, and roof collapse, are still occurring, which seriously threaten tunneling safety. To eliminate the geo-hazards and ensure tunneling safety, ground surface pre-grouting (GSPG) was proposed and implemented for the first time to reinforce the regional engineering rock mass for this proposed 800-m-deep underground opening passing through large fault zones. The minimum grouting pressure of GSPG at a depth of 800 m below the surface is put forward based on hydraulic fracturing theory, providing valuable guidance for GSPG engineering practice. Engineering practice demonstrates that GSPG eliminates geo-hazards, improves the objective rock mass stability, and ensures tunneling safety. Field measurements indicate that the displacement velocity of the surrounding rock shows an obvious fluctuation response under the influence of GSPG, and the impact of GSPG on the stability of the 800-m-deep underground opening that has been excavated dramatically decreases as the distance from the grouting borehole increases. Moreover, there is a strong negative exponential correlation between the maximum velocity of deformations and the distance from the grouting borehole. In addition, the safe distance underground during GSPG is greater than 137 m.