Research and application of key technologies for deep-buried long tunnels crossing active fault zones——a case study of the Shizishan Tunnel in the Central Yunnan Water Diversion Project
OUYANG Lin
ZHANG Shiqiang
REN Hengqin
JIANG Jibin
JIACI Lamu
ZHAO Lei
Abstract：The Shizishan Tunnel of the Central Yunnan Water Diversion Project has a total length of 21.17 km and a maximum burial depth of 694 m.The downstream main tunnel of its No.4 branch crosses the F16 Chenghai-Binchuan active fault zone.This fault zone,active since the Late Pleistocene,is characterized by soft surrounding rock,high ground stress,abundant seepage,and multiple clay interlayers.During construction,fractured surrounding rock with extremely low rock mass strength,dripping and seeping water,and other unfavorable conditions were encountered,leading to problems such as large daily deformation,cracking and delamination of initial shotcrete,and collapse.Based on advanced geological forecasting,comprehensive assessments indicated risks of B-level sudden water inrush and extremely severe squeezing deformation.By adopting integrated construction technologies,including pre-excavation advanced exploration,pre-consolidation grouting,and advanced support,as well as increasing reserved deformation allowance,optimizing excavation methods,strengthening initial support,adding temporary struts,implementing drainage and pressure reduction,enhancing temporary monitoring during construction,and promptly following up with secondary concrete lining and permanent monitoring after excavation,the project successfully resolved technical challenges such as sudden water and mud inrush,significant vertical and horizontal displacements,and extremely unstable surrounding rock.These key technologies ensured the safe crossing of the F16 Chenghai-Binchuan active fault zone and can provide reference for tunnel construction in large-scale water diversion projects through similar active fault zones.
Keywords：deep-buried long tunnelactive fault zonesurrounding rock stabilitykey construction technologyCentral Yunnan Water Diversion Project
Publication Date：2025-09-12
Online Publishing Date：2025-09-22(First online date of this platform, not the publication date of the document)
Pages：9( 57-65 )