北京市门头沟区G109国道K40+800 m崩塌特征及成因分析

Characteristics and genetic analysis on collapse at K40 + 800 m of highway G109 in Mentougou District, Beijing

2021年7月15日,北京市门头沟区妙峰山镇G109国道发生崩塌灾害,崩塌体方量约280 m^(3),造成道路全幅中断,防护栏损毁。基于灾后现场应急调查资料,在系统收集灾害发生区域地质及降雨资料的基础上,分析阐述了崩塌灾害的成因及变形演变过程。初步结果认为:该崩塌灾害为滑移式崩塌,陡峻的边坡及褶皱、断层、穹窿构造的发育为崩塌的形成提供了有利的地形地质条件,顺坡向的层理面和其余两组节理面为崩塌的形成提供了有利的坡体结构条件,G109国道修建切坡加剧了坡体的变形,降雨是崩塌发生的直接诱发因素。该崩塌变形演变过程可分为4个阶段:构造作用下的初始变形阶段,风化、温差、人类工程活动作用下的时效变形阶段,降雨、风化、冻融等因素持续作用下的累积变形阶段,降雨诱因下的破坏失稳阶段。

On July 15, 2021, collapse disaster occurred along highway G109 in Miaofengshan town of Mentougou district. The collapse volume is about 280 m~3with the traffic completely disrupted and the fences badly damaged. Based on the first-hand data of post-disaster on-site emergency investigation, and systematic collection of regional geological and rainfall data, this paper analyzes the basic characteristics and the cause of the collapse and deformation evolution process of the collapse. Preliminary results show: the collapse is sliding collapse in nature;steep slope and the development of folds, faults, and dome structure provide a favorable terrain and geological conditions for the collapse;the slope to the bedding plane and the rest of the two groups of joint surface provide favorable slope structure conditions;cutting slop resulted from G109 construction magnifies deformation of the slope;and rainfall serves as the direct cause to the collapse disaster. The collapse deformation evolution process can be divided into four stages: initial deformation stage caused by tectonic action;aging deformation stage caused by action of weathering, temperature difference and human engineering activities;accumulated deformation stage caused by continuous rainfall, weathering and other factors;destruction and instability stage phase induced by rainfall.