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“5.12”汶川地震不仅直接造成了巨大的人员和财产损失,同时还诱发了大量的崩塌、滑坡、泥石流等次生山地灾害。崩塌、滑坡直接为泥石流活动提供了丰富的松散固体物质,再加上在地震荷载的多次往复作用下,山体的整体性遭到破坏,大量坡体失稳,岩体破坏,使这些泥石流沟在今后较长一段时间内处于活跃期。2008年6月18日,位于重震区的茂县东兴乡竹包头沟暴发泥石流,将主河湔江堵断随后溃决,对临近的“302”省道造成了较为严重的危害。该沟上游段沟床比降大,岸坡较陡,流域内出露的岩石以千枚岩为主,易风化破碎,在地震中形成许多崩塌和滑坡,加之流域降水集且多局地性暴雨,有利于泥石流的发育。在调查访问的基础上,估算该次泥石流的容重为2.0 g/cm3,为高容重粘性泥石流。计算出其流速在10 m/s以上,流量约300 m3/s,总规模为1×105m3。竹包头沟泥石流固体物质的主要来源为地震引发的崩塌和滑坡堆积物,根据遥感资料测算,总方量达3×1010m3以上,再次暴发泥石流的可能性很大。为减弱泥石流活动,减轻泥石流造成的损失,提出以下应对措施:以生物防治措施为主,减少泥石流物源;加强监测,及时警报,减轻泥石流危害;普及泥石流知识,提高防灾减灾能力。
“5.12 ” Wenchuan earthquake not only directly caused tremendous human and property losses, but also induced a large number of landslides, mudslides and other secondary mountain hazards. Collapse and landslide directly provide abundant loose solid material for the debris flow activity. In addition, under the repeated reciprocating action of the earthquake load, the integrity of the mountain is destroyed, a large number of slope instability and rock mass destruction make these debris flow ditches In the future for a long period of time in the active period. On June 18, 2008, mud-rock flow was triggered at Zhu Baotou Gou, Dongxing Township, Maoxian County, in the earthquake-stricken area. After the main river Qijiang was intercepted, it was subsequently ruined, causing serious damage to the nearby “302” provincial highway. The ditch-bed ratio in the upper reaches of the ditch is larger and the bank slope is steeper. The rocks exposed in the basin are dominated by phyllites and are prone to weathering and crushing. Many collapses and landslides are formed in the earthquakes. Rainstorm, is conducive to the development of debris flow. On the basis of investigation and interview, it is estimated that the bulk flow of the debris flow is 2.0 g / cm3, which is a high-volume-weight sticky debris flow. Calculated at a flow rate of 10 m / s or more, the flow rate of about 300 m3 / s, the total scale of 1 × 105m3. The main source of debris flow debris in bamboo Baotou Gully is earthquake-induced collapse and landslide deposits. According to the remote sensing data, the total square amount is more than 3 × 1010m3, and the possibility of debris flow again is very high. In order to reduce the debris flow activity and reduce the losses caused by debris flow, the following countermeasures are proposed: biological control measures should be taken to reduce the source of debris flow; monitoring should be carried out to timely alert the debris flow hazards; universal knowledge of debris flow should be made to improve disaster prevention and reduction capacity.