滑坡碎屑流高速远程机制环剪试验研究  

Research on rapid and long-runout mechanisms of rockslide debris using ring shear tests

作　　者：张明[1,2] 王正波[1,2] 孙琳[3] 

机构地区：[1]中国地质大学岩土钻掘与防护教育部工程研究中心,湖北武汉430074 [2]中国地质大学工程学院,湖北武汉430074 [3]河北交通职业技术学院,河北石家庄050035

出　　处：《岩石力学与工程学报》2016年第A01期2673-2681,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：中央高校基本科研业务费专项资金资助项目(CUGL140408);国家自然科学基金资助项目(41472264;41202200)~~

摘　　要：在我国西部山区,由高速远程滑坡碎屑流导致的群死群伤事件时有发生,对滑坡碎屑流的高速远程机制研究迫在眉睫。以汶川地震触发的文家沟高速远程滑坡碎屑流为研究对象,利用其堆积物中出露的冲沟对碎屑流堆积物的堆积结构进行研究,结果表明,碎屑流堆积物具有明显的反序结构;进一步利用环剪试验对碎屑流流动过程中不同深度处碎屑颗粒的长距离剪切过程进行模拟,结果显示,颗粒破碎是滑坡碎屑流堆积物反序结构形成的主要原因之一,碎屑流流动过程中由于底部颗粒所受正应力最大,因此破碎越彻底,而向上碎屑颗粒所受正应力逐渐减小,破碎程度也逐渐减小,因此形成反序结构;而底部碎屑颗粒破碎导致碎屑流剪切强度降低,进一步导致碎屑流底部与地面之间摩擦阻力降低,是滑坡碎屑流能够高速远程的主要原因之一。研究成果能够为西部山区高速远程滑坡碎屑流的致灾范围预测提供科学依据,具有一定的理论和实际意义。Catastrophic event induced by rapid long runout rockslide debris occurs frequently in West mountainous areas of China. There is an urgent need to study transport mechanisms of this kind of geohazard. Taking the Wenjiagou rockslide debris triggered by 2008 Wenchuan earthquake for example, the paper studies the internal structure of its deposit through the gully exposed in the deposit. The result indicates that ＂inverse grading＂ structure is obvious in the deposit, and the mean size of grains gradually increases from the base to the surface. The ring shear test is used to model the long-shear course of grains at different depths during transport course. The results suggest that grain crushing is one of the main reasons leading to inverse grading structure of the deposits. During transport, the normal stress is largest at the base and progressively decreases from the bottom up to the surface. The grains at the base experiences maximum normal and shear stresses and are crushed to finest material. Accordingly, the frictional resistance of the grains at the base decreases, reducing the frictional resistance between debris and the ground. We term this process the ＂finer-base effect and suggest that it may be one of the mechanisms leading to high speed and long runout of rockslide debris. The conclusions of this paper could be a scientific basis for hazardous forecasting of rapid and long-runout rockslide debris in mountainous areas in West China.

关 键 词：边坡工程 滑坡碎屑流 高速远程机制 反序结构 环剪试验 颗粒破碎 

分 类 号：P642[天文地球—工程地质学]