卜寺沟水电站环境边坡危险源分类及危险度评价

CLASSIFICATION AND RISK RATING ASSESSMENT OF HAZARD SOURCES IN SURROUNDING SLOPE OF BUSIGOU HYDROPOWER PROJECT

水电工程环境边坡上任一小型局部失稳块体均会对其下水工建(构)筑物和人员造成巨大威胁,对环境边坡的评价应重点关注局部、个别块体的稳定性的调查与评价。卜寺沟水电站环境边坡共发育危险源100处,其中左岸发育61处,右岸发育39处,在大量精细现场调查分析的基础上,分别按地质成因、规模、破坏机制对其进行分类。按地质成因将危险源分为孤石(群)、危石(群)(一般≤100m3)、危岩体、高位覆盖层等4种类型。考虑危险源自身稳定性及工程重要性程度,选取危险源自身、途径边坡、触发因素等3个一级指标,选取与一级指标对应的9个二级指标和32个基础指标,建立指标齐全、易于操作的环境边坡危险源危险度评价体系,按评分值大小将危险度分为高、中、低3个等级。利用该评价体系对卜寺沟水电站环境边坡危险源危险度进行评价,评价结果表明:高危险度的危险源为19处,中等危险55处,低危险度26处,评价结果较符合实际,该体系对于危险源防治具有一定的工程意义。

A small local failure block in surrounding slope of hydropower project can become a big potential hazard for hydraulic construction（structure） building and human security. So the assessment of surrounding slope has to pay more attention to the stability investigation and assessment of the local and small block. There are a total of 100 hazard sources existing in surrounding slope of Busigou hydropower project. 61 of them are developed in the left bank and 39 in the right bank. Based on a large number of precise field investigation and analysis, a classification is proposed according to geological genesis, scale and failure mechanism respectively. According to geological gene sis, hazard sources are divided into four types： （group of ）isolated stone, （group of ）dangerous rock （generally 〈 100m3） ,dangerous rock mass and high position covering layer. Considering the hazard stability and degree of pro ject importance, hazard rating assessment system（HRAS） of surrounding slope which has enough easily valued indicators is established according to three first level indicators （the hazard source, path and inducing factors）, nine secondary indicators （stability, potential energy, hazard sources＇ shape, path＇s geometric features, vegetation growth, earthquake and rainfall）, and 35 basic indicators. According to the level of values, hazard rating is divid ed into three levelshigh, medium, and low level. Using this assessment system to evaluate the hazard rating of surrounding slope of Busigou hydropower project, the evaluation results show that in the total of 100 hazard sources, 19 are of high hazard rating, 55 of medium and 26 of low hazard sources. The result is largely correspondence to re ality. This assessment system has some engineering significance for hazard source prevention and controlling.