奎屯河新龙口右岸山体崩塌原因及再次失稳可能性分析

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。     

The rock-avalanche of February 1995 at Claix (French Alps)

The sedimentology of a rock-avalanche involving ca. 7·10³ m³, that happened on February 1995 at Claix, the French Alps, is analysed here. The talus shows a proximal depression due to the impact of the debris, then a grooved area with few, mainly sandy silt deposits and a downslope accumulation of coarse debris that reaches up to 3 m in thickness. The material underwent mass movement as demonstrated by the steep distal front, the strong fabric strength and the thrust planes. The greatest part of the deposits consists of a clast-supported to partially openwork debris with angular clasts over a sheared matrix-supported basal layer. The largest blocks, often more than 1 m in length, are concentrated at the surface and the front. The overall sedimentological characteristics are similar to those of the small dry grain flows that occur usually on rockfall talus, except for the abundance of fine-grained particles that results from intense cataclasis during flow. It is suggested that the deposits of such medium-scale rock-avalanches, probably not uncommon in seismic regions, may have been confused in previous studies with other slope mechanisms such as debris flow and rockfall.