奎屯河新龙口右岸山体崩塌原因及再次失稳可能性分析

CAUSES FOR THE ROCK AVALANCHE ON THE RIGHT BANK OF XINLONGKOU ON THE KUITUN RIVER AND PROBABILITY OF ITS REOCCURRENCE

奎屯河新龙口段山体历史上多次发生山体塌滑破坏,最近一次山体崩塌较为反常地发生在1月寒冷季节,而不是通 常的7、8月雨季,针对该段山体频繁发生破坏而且还出现反季节崩塌这种特殊情况,从区域地质背景、地震作用、地形地貌、气 候及降水等几个方面分别详细论述了产生崩塌的原因,同时指出这次反季节崩塌产生的触发原因在于气候反常造成雪水入 渗、短时间内发生多次冻融,裂隙中液态水结冰产生膨胀力诱发了此次山体崩塌。采用赤平投影分析论证了潜在崩塌的可能 性问题,指出发生此次崩塌后的右岸山体仍然未达到稳定状态,还可能再次发生破坏,同时应用实体比例投影法圈定了最有 可能破坏的山体位置并对崩塌方量进行了计算,从而对山体潜在崩塌可能性及规模有了一定把握,对该段山体崩塌的防治具 有实际的工程意义。

Rock-avalanches have often occurred in the monsoon season during the months of July and August in the Xinlongkou region on the Kuitun River. However, the latest avalanche took place in January. To explore the causes for the high frequency of occurrences of rock-avalanches in that area, the authors assess different factors such as regional geological conditions, seismic activities, topography, climate and rainfall indexes. Among them, the fragile geological conditions resulted from long historical tectonic movements attributed to seismic activities and favorable climate conditions have triggered rock avalanches in the area. However, frequent thawing and freezing of snow is an extremely critical inducement for the occurrence of avalanches in winter. In the latest episode, the temperature was abnormally high at noon, and it dropped very quickly at night during that specific winter. High temperature allows snow to thaw and penetrate into cracks during daytime, and freeze and consequently expand in volume at night, which in turn triggered the avalanche. Therefore, the thawing and freezing of snow is a very important factor that should be considered in assessment of rock avalanche for some special areas. This paper also assesses the probability of reoccurrence and scale of avalanche events in the region.