高原山区铁路工程建设地质安全评价:思路与方法

Geological safety evaluation of railway engineering construction inplateau mountainous region: ideas and methods

工程地质评价是保障重大工程建设安全的重要工作内容。本文面向新时代重大工程规划建设需求,提出了地质安全评价的内涵和目标任务,以高原山区铁路工程建设为例,阐述了地质安全评价的方法、工作流程和应用实例。着重提出:服务铁路工程的不同规划建设阶段对应于不同的评价尺度要求,规划阶段适用区域廊带尺度,以区域地壳稳定性评价为基调,基本比例尺可≤1:5万,目的是定性给出廊带安全性或适宜性;可研阶段适用关键区段尺度,以工程地质稳定性评价为基调,基本比例尺1:1万~1:2.5万,目的是进一步厘定不良地质组合和重大地质风险,指导线路比选和优化;设计阶段适用工程场地尺度,聚焦具体的地质风险或工程岩体稳定性问题,基本比例尺1:2000,依据相关技术标准和专题分析研究进行专项评价。通常,随着地质风险等级从高到低,对应地质安全等级从低到高;地质安全评价结果可根据地质风险等级与防治难度划分为安全、较安全、欠安全和不安全四个等级,目前技术条件下达不到安全要求的地带应首先考虑避让。建议把地质安全评价纳入国家级工程建设管理的必要环节,并加快相关技术标准的制订。

Engineering geological evaluation is an important work to ensure the safety of major engineering construction. Facing the planning and construction needs of major projects in the new era, this paper puts forward the connotation and objectives of geological safety evaluation. Taking the railway engineering construction in plateau mountainous region as an example, the method, workflow and application examples of geological safety evaluation are discussed. Some conclusions are as follows: different stages of railway construction correspond to different evaluation scale. The regional scale, less than 1:50000, can be used in the planning stage, which is based on the evaluation of regional crustal stability, aiming to qualitatively give the railway corridor safety or suitability. In the feasibility study stage, the key segment scale, such as 1:10000~1:25000, can be used for evaluation of the engineering geological stability, so as to further determine the poor geological combination and major geological risks, and guide route optimization. In the design stage, the site scale such as 1:2000 is suitable, which is to focus on specific geological risks or engineering rock mass stability issues. Special evaluations are carried out according to relevant technical standards and thematic analysis and research. In general, as the geological risk degree goes from high to low, the corresponding geological safety degree goes from low to high. According to the level of geological risk and the difficulty of prevention and control, the geological safety evaluation results can be divided into four degrees including safe, sub-safe, relatively unsafe and unsafe. The segments, where safety requirements cannot be guaranteed under current technical conditions, should be avoided for site selection. It is suggested to incorporate geological safety evaluation into the necessary processes of national engineering construction management, and speed up the formulation of relevant technical standards.