喜马拉雅东构造结工程选址面临的地质安全挑战

Geo-safety challenges against the site selection of engineering projects in the eastern Himalayan syntaxis area

喜马拉雅东构造结是全球构造活动最强烈、地质环境最复杂、地质灾害最频发的地区之一,工程规划建设面临板块构造带的构造错断、深埋工程灾变、松动山体失稳、流域性地质灾害链等灾难性地质安全风险。如何在活动构造带内选择相对稳定与安全的场址,实现工程规划建设与运营的地质安全风险最小化,是当前工程地质领域的重要课题。文章系统梳理了东构造结地区重大地质安全问题,发现传统的工程选址理论已无法满足喜马拉雅东构造结工程选址的要求,工程选址面临地质演化过程与工程区地质建造不清、构造活动性与强震灾害风险突出、深部构造应力场与灾变研究薄弱、超高位超远程地质灾害链形势严峻等重大地质安全挑战。为此,文章从“区域地质演化与工程地质问题”“活动断裂及工程安全风险”“复杂地应力场及工程灾变风险”“流域性地质灾害链工程风险”“东构造结工程选址理论方法”共5个方面提出工程选址主要研究方向,为完善工程选址风险评价与防控方法提供思路。

The eastern Himalayan syntaxis is one of the regions having the most intense tectonic activities,the most complex geological conditions,and the most frequent geohazards in the world.The planning and construction of engineering projects are faced with four types of catastrophic geo-safety risks,including tectonic faulting in the plate tectonic belt,disaster occurrence of the deep-buried tunnels,instability of loose mountains,and regional geological disaster chain.It is a critical topic in the field of engineering geology how to select relatively stable and safe sites in active tectonic zones to minimize the geo-safety risks of planning,construction,and operation of engineering projects.This paper summarized the major geo-safety problems in the eastern Himalayan syntaxis.Accordingly,it revealed that traditional site selection theories hardly satisfy the requirements of the engineering projects in the eastern Himalayan syntaxis area.The site selection encounters geo-safety challenges caused by unclear geological evolution process and construction,prominent disaster risk of tectonic activity and strong earthquake,weak research on the deep tectonic stress field and disaster evaluation,and severe ultra-high-elevation and ultra-long-runout geological disaster chain.Thus,this paper suggested the main research directions of the site selection from five aspects:(1)regional geological evolution and engineering geological problems,(2)active fault and engineering safety risk,(3)complex in-situ stress field and engineering disaster risk,(4)engineering risk of regional geological disaster chain,and(5)theory and method of site selection in eastern Himalayan syntaxis.This paper provides ideas for improving the risk assessment and prevention methods of site selection of engineering projects.