摘要
易贡巨型山体崩塌 滑坡是国内规模最大的超高速远程滑坡。该滑坡位于西藏波密县易贡乡境内的扎木弄沟源头至沟口外的易贡藏布两岸。滑坡的最大水平位移为 6 7～ 7 0km ,其堆积体前缘最大宽度约 3 0km ,纵向最大长度 4 6km ,最大厚度近 80m ,滑坡体表面总面积为 8 6 9km2 ,体积达 3 0× 10 8m3。从山体崩塌开始到滑坡滑动直至停积就位 ,仅用了约 3min ,滑坡平均运动速度为 37～ 39m s。在受到巨大撞击和在高速运动中解体的崩塌岩块因其质量大而分布在滑坡体的中后部 ,滑坡体前缘及两侧是混有大量空气、粉尘和富水的碎屑物质形成的碎屑流堆积。因在运动中主流线与两侧的速度有差异 ,产生的剪切力以及主流前缘受到原堆积垅的阻挡 ,使两侧富含高密度气团的碎屑流运动分别出现典型的左旋及右旋的涡流特征。高速碎屑流使滑坡堆积体两侧及前缘普遍受到裹夹着砂、石与水的高密度气团冲击。从滑坡体的主堆积区向前缘和两侧清楚地呈现出密度流差异 ,并受原始地形影响 ,表现为不对称的堆积特点。滑坡在高速运动过程中具有明显的气垫效应 ,在坠落停积后大量气体快速逸出 ,并伴有喷水冒砂和局部塌陷等现象。该滑坡是受区域性强烈上升、丰富的降水以及断裂构造等因素控制 ,由地形条件、地层结构、岩体物理力学性质、
Yigong landslide is the largest landslide in China with super high speed and long distance coverage.It locates on the bank of the Yigong\|Zangbu in Yigong village,Bomi county,Tibet.The longest horizontal displacement is 6\^7\|7\^0?km.The biggest width,length and thickness of the landslide accumulation area are about 3\^0?km,4\^6?km and 80?m.The total surface area is 8\^69?km\+2 and the total volume is 3\^0×10\+8m\+3.The sliding process took only 3?min at the average speed of 37\|39?m/s.The disjointed rock mass formed by high speed collision distributes at the middle and the back of the landslide body.Fragmental products with a great deal of air,dust and water stack at the foreside and two sides of the landslide body.The shear stress is produced by the speed difference between the main line and the sides of the sliding body,and the main stream of the landslide is blocked by the original accumulation,therefore,the two sides of the sliding body present a typical levorotatory and dextral eddy characteristics.The high density air mass with sand,stone and water impacts the two sides and the leading edge of the high\|speed fragmental flood.The difference of density clearly presents at the front and two sides of the main accumulation area,and it is not completely symmetrical because of the original landform.The landslide has obvious air cushion impression in the process of high\|speed movement.When it falls and stops,a great deal of air is released with local collapse.The landslide is controlled not only by regional crustal rising,abundant rainfall and faults,but also by landform,structure of the strata,physical and mechanical properties,primary structural surface and secondary fissure by thawing.Ice\|snow melting has made the intragranitic pressure of pore water increased and led to mountain collapse(the volume of one collapse is 3\^0×10\+7m\+3 and the height is about 2580?m),activating the high\|speed landslide consequently and showing an entirety characteristic of collapse\|landslide.Unlike other wriggled large\|scale landslide,this landslide has the character of uncertainty and posthumousness.Considering the huge collapse\|landslide and its spatial coverage changing with time,it is noticed that in a specific spatial\|temporal coverage,large amount of ice\|snow melting leads to mountain collapse,and mountain collapse induces super high\|speed long distance landslide,and the landslide body blocks the Yigong\|Zangbu to be a lake submerging the farmland,tea\|making farmland,grass land,houses and forest,and then the lake flooded Yigong\|Zangbu,Palong\|Zangbu,Yalu\|Zangbu.As a result,the slopes in the river valley are apt to occur shallow retrogressive landslides and collapses.The landslide is actually a huge geological hazard chain with temporal\|spatial series characteristics.
出处
《中国地质灾害与防治学报》
CSCD
2002年第3期9-18,共10页
The Chinese Journal of Geological Hazard and Control
