研究：地震数据揭示了安第斯山脉落石的规模和影响

　　

　　

　　落石是山区常见的自然灾害，尤其是在安第斯山脉，陡峭的山坡、地震活动和气候变化都可能引发落石。

　　它们会对道路、铁路、管道、电线和建筑物造成破坏，也会造成人员伤亡。

　　因此，量化与落石有关的风险对于规划和实施缓解措施至关重要。

　　来自智利大学、洛桑大学和瑞士联邦森林、雪和景观研究所(WSL)的一组研究人员开发了一种评估安第斯山脉岩崩风险的新方法。

　　该方法结合现场观测、遥感数据、数值模拟和统计分析，估算不同情景下岩崩的频率、震级和影响。

　　研究人员将该方法应用于智利的两个案例研究:圣地亚哥附近的Cajón del Maipo山谷和科金博地区的Elqui山谷。

　　他们利用无人机、激光扫描仪和照相机收集了有关岩崩特征和分布的数据，如大小、形状、体积和位置。

　　他们还利用卫星图像和历史记录来确定引发落石的因素，如地震、降雨、融雪和温度变化。

　　利用Rockyfor3D软件，研究人员模拟了不同条件下数千次落石的轨迹和速度，如斜坡角度、摩擦力和植被覆盖。

　　然后，他们使用一种叫做贝叶斯网络的统计模型，计算出岩崩到达并破坏不同危险元素的概率，比如道路、建筑物和人。

　　为了减轻岩崩的危害，一般采用两种技术，即主动保护技术和被动保护技术。

　　主动防护措施是防止落石发生的措施，而被动防护措施是减少落石造成的破坏。这些措施包括在斜坡上进行干预，以减少发生岩崩的可能性。

　　这可以通过以可控的方式移除松散的岩石(移除)、改变边坡的结构(重新倾斜)、将岩石块固定在适当的位置(加固边坡)或通过边坡排水来实现。

　　清除是指部分或全部清除松散或不稳定的岩石，以减少岩崩的发生。

　　它可能包括对斜坡轮廓的修改;水平台阶是非常有效的，因为它们减少了斜坡的张力，减缓了侵蚀速度，并根据台阶的宽度阻止了落块。

　　同时，边坡加固的目的是将倾斜的岩块固定到位，减少岩崩的发生。各种类型的边坡加固是可用的，这些是:销子，螺栓和锚，可用于单个块或岩体。

　　边坡排水的目的是降低岩体内部孔隙水压力，从而增加边坡的稳定性。

　　被动保护措施包括在坡脚或沿落石路径采取干预措施，以减少冲击或改变落石的轨迹。

　　These measures can be classified into three categories: barriers, rock sheds, and catchment areas. Barriers are structures that intercept and stop the falling rocks before they reach the protected area.

　　The protected area and allow the falling rocks to slide over them. They can be made of concrete, steel, or timber.

　　Catchment areas are zones that collect the falling rocks and prevent them from reaching the protected area. They can be natural or artificial, such as ditches, berms, or forests.

　　The effectiveness of these measures depends on several factors, such as the size, shape, and velocity of the falling rocks, the geometry and material of the slope, the design and maintenance of the structures, and the environmental conditions.

　　Therefore, it is important to conduct a comprehensive risk assessment and select the most suitable and cost-effective measure for each case.

　　The results of the study showed that rockfall risk varies significantly depending on the location, the season, and the triggering factor.

　　For example, in the Cajón del Maipo valley, the risk is higher in winter than in summer, due to the effect of snowmelt and freeze-thaw cycles on the stability of the rocks.

　　In the Elqui valley, the risk is higher in spring than in autumn, due to the influence of rainfall and temperature fluctuations on the rock fractures.

　　The study also revealed that the most vulnerable elements at risk are the roads, which are exposed to frequent and large rockfalls, especially in narrow sections of the valleys.

　　The researchers estimated that the annual expected loss due to rockfall damage to roads is about 1.5 million US dollars in the Cajón del Maipo valley and about 0.5 million US dollars in the Elqui valley.

　　They hoped that their method can help decision-makers and stakeholders to evaluate and reduce rockfall risk in the Andes and other mountainous regions.

　　Furthermore, they suggested that the method can be used to identify the most critical areas and seasons, to design and implement effective mitigation measures, such as rockfall barriers, nets, and fences, and to improve the emergency response and recovery plans in case of rockfall events.