特殊地形及物源限制条件对泥石流暴发规模的影响研究——以青海加吾矿区玛日当沟泥石流为例

Study of special terrain and source limit condition on the influenceof debris flow scale:an example of the debris flow at Maridang gullyin Jiawu mining area of Qinghai

加吾矿区位于青藏地块区内柴达木盆地东缘区的青海南山微造山带内,为保障矿区资源勘探及开采的有序开展,预防泥石流等突发性地质灾害,针对矿区重点采区玛日当沟流域进行了系统带状勘察,建立了对该区泥石流致灾背景的充分认知。基于此,利用同德县气象观测资料,根据《泥石流灾害防治工程勘查规范DZ/T 0220-2006》、相关经验公式和费祥俊等(2004)关于含有细颗粒水石流起动条件理论,显示矿区玛日当沟具备了泥石流形成的三大有利条件。分析表明:在特殊地形及物源限制条件下,由于泥石流起动的容重与流速受限制,玛日当沟20年及以上一遇规模的泥石流实际暴发规模相较于规范及经验公式计算结果偏小,且流体冲击力会趋于稳定,在进行泥石流防治工程设计时应以容重与流速临界值作为设防依据。

Jiawu gold deposit is located in Qinghai-Nanshan micro orogenic belt in the east margin of Qaidam basin,Qinghai-Tibet plateau area.In order to ensure the progress of the mineral exploration and mining,and to prevent from the occurrence of the sudden geological disaster effectively,such as debris flow within the area,a detailed investigation of the Maridang gully river basin,the key work area,is carried out systematically in the mining area for the establishment of a fully knowledge of the background of sudden debris flow.Based on this,using the meteorological observation data of Tongde County,according to the"Debris Flow Disaster Prevention Engineering Survey Stanard DZ/T 0220-2006",related empirical formulas and the relative study made by Fei Xiangjun et al.(2004),it is shown that in the Maridang gully there are three favorable conditions for the formation of debris flow.The analysis indicates that the actual scale of debris flow in twenty years once is smaller than that from specification and empirical formula,and fluid impact force would be stable.In the design of debris flow prevention engineering,the critical value of bulk density and flow velocity should be used as the basis of fortification.