强震诱发大型岩质滑坡的滑面中岩石角砾的高温胶结作用
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摘要
汶川特大地震在北川县陈家坝乡地区诱发了许多地质灾害,其中孙家园滑坡后壁出露有一种特殊的红褐色岩石壳体,形态如岩石熔化重新胶结一般,甚至具有比基岩还要高的强度。根据对孙家园滑坡后壁所出露的红褐色壳体的形态特征、出露条件和其矿物成分的鉴定,建立了一种新的岩型——滑面角砾岩。通过对滑带角砾快速胶结成岩机理的分析,并结合孙家园滑坡的特点,证明了在强震作用和特殊的地质条件下,滑带岩石角砾可以满足产生快速铁质胶结所需要的温度条件,而且这个温度远低于岩石矿物熔化所需温度。
Whenchuan earthquake triggered many geo-hazards in Chenjiaba in Beichuan area,and Sunjiayuan rockslide was one of the biggest ones In the rockslide back-wall a special russet rock shell was revealed,which had strength higher than that of the underlying bed rock.A new definition named sliding-surface breccia was brought according to the characteristics and mineral identification of this special rock shell.By analyzing the mechanism of fast rock granular cementation,it is proved that under the severe earthquake and certain specific geological and topographical conditions,the temperature in the sliding zone can rise to meet the required temperature under which rock particles in the sliding zone can be conglomerated by ferruginous cementation.In addition,this temperature is far lower than the mineral melting temperature of rocks.
Whenchuan earthquake triggered many geo-hazards in Chenjiaba in Beichuan area,and Sunjiayuan rockslide was one of the biggest ones In the rockslide back-wall a special russet rock shell was revealed,which had strength higher than that of the underlying bed rock.A new definition named sliding-surface breccia was brought according to the characteristics and mineral identification of this special rock shell.By analyzing the mechanism of fast rock granular cementation,it is proved that under the severe earthquake and certain specific geological and topographical conditions,the temperature in the sliding zone can rise to meet the required temperature under which rock particles in the sliding zone can be conglomerated by ferruginous cementation.In addition,this temperature is far lower than the mineral melting temperature of rocks.
引文
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[2]王效宁.滑坡温度特性研究及其在三峡库岸稳定分析中的应用[J].岩石力学与工程学报,1993,12(2):126-137.
[3]殷坤龙.滑坡灾害预测预报[M].武汉:中国地质大学出版社,2004.
[4]MASCH L,WENK H R,PREUSS E.Electron microscopy study of hyalomylonites—evidence for frictional melting in land-slides[J].Tectonophysics,1985,115:130–160.
[5]铁道部第一勘测设计院.铁路工程地质手册[S].北京:中国铁道出版社,2005.
[6]陈运泰.汶川特大地震的震级和断层长度[J].科技导报,2008,26(10):26–27.
[7]夏宗国.断层岩的分类、识别及其形成条件[J].地质论评,1983,29(6):578-583.
[8]杨主恩,应思淮,林传勇,等.北京密云北石城断裂带的断层岩特征及其地震事件的可能证据[J].地震地质,1981,3(4):1-17.
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