摘要
我国多山,崩塌灾害频繁发生,相应的风险评价也得到了越来越多的关注。由于崩塌发生和运移过程的高度不确定性以及历史数据的不完备,往往很难进行相应的定量风险评价。四川罗家青杠岭的崩塌现场非常典型,而且现场资料较全、历史数据较多并且明确,是开展崩塌风险定量研究的很好实例。通过现场工程地质调查、测绘和统计分析,确定了历史崩塌的物源区、堆积区、最大运移距离、年发生概率以及坡体上的4块典型危岩体A-D。基于历史崩塌堆积区的块石统计特征以及物源区危岩体失稳启动位置的不确定性,利用二维Rockfall模拟软件对所在坡面的恢复系数及摩擦系数进行了反演。在此基础上,对危岩体A-D失稳后的运动特征进行了随机性数值模拟和统计分析,从而确定了崩塌的到达概率。基于崩塌发生概率、到达概率、承灾体时空分布概率和易损性的乘积,作者对罗家青杠岭崩塌进行了定量风险评价。评价结果表明,危岩体A和D的风险值处于不可接受的风险区间,块石B和C的风险值处于警告的风险区间,严重威胁着坡脚附近居民的生命财产安全,有必要采取相应的防灾减灾措施。
China is a country with many mountains. The risk assessment of rockfall has gained more attention due to the increase of rockfall hazard in mountainous areas. Rockfall risk analysis is inherently complex and difficult. Such difficulties are due to many factors. They include high uncertainties of rockfall occurrence and transport, lack of historical data, strongly site-specific nature of rockfall, difficulty in quantifying and modelling spatial rockfall distribution, quantifying the heterogeneity of vulnerability of different elements at risk and variability in temporal vulnerability, These factors lead many limitations in quantitative risk assessment. Rock falls in Luojiaqinggangling, Sichuan Province are a scarce example to study risk assessment quantitatively due to the complete field data and rich historical data. Based on the engineering geological investigation, topographical survey and statistic analysis, this paper confirms the provenance, accumulation area, maximum transport distance, annual probability of occurrence and four potentially unstable blocks A-D. Rockfall risk for exposed people in Luojiaqinggangling is estimated by the product of three conditional probabilities ( annual probability of occurrence, reach probability and temporal-spatial probability) and vulnerability. Based on the rich statistical data of historical rockfall, the annual probability of occurrence is derived from a magnitude-cumulative frequency ( MCF) distribution of rockfall events. Considering the size statistical characteristics of the historical rockfall and the position uncertainties of unstable blocks in provenance, this paper conducts the inversion analysis of slope restitution and friction coefficients. It uses the two-dimensional simulation software Rockfall. On these basis, the arrival probabilities of unstable blocks A-D were obtained after numerous random simulation and statistical analysis. Pedestrians and residents that are confirmed as the affected body based on field investigation, temporal-spatial probability depends on the mobility of the exposed elements. It is calculated using empirical equation according to the movement feature of affected body. The vulnerability was determined combining the kinetic energy of rockfall and the location of affected body. According to the product of occurrence probability, arrival probability, temporal distribution probability and vulnerability, the quantitative risk assessment of this rockfall is achieved. The results show that the risk values of block A and D are in a unacceptable risk range, and the risk values of blocks B and C are in a warning range. Those unstable blocks could threaten the life safety of the residents, therefore, it is essential to take appropriate measures for the disaster prevention and mitigation.
出处
《工程地质学报》
CSCD
北大核心
2017年第2期520-530,共11页
Journal of Engineering Geology
基金
国家自然科学基金(41402285
40502027)资助
关键词
崩塌
概率分析
随机性数值模拟
反演
定量风险评价
Rockfall, Probability analysis, Random numerical simulation, Inversion, Quantitative risk assessment