| 摘要: |
| 陡倾层状岩体的深层倾倒变形是我国西南深切河谷常见的一种地质现象。第四纪以来，伴随青藏高原隆升，强烈的河谷下切是导致这一现象的重要原因。本文以澜沧江上游河谷哑贡倾倒变形体为例，在详细调查基础上，采用底摩擦重力试验和数值计算的方法，对河谷下切过程中该倾倒变形体的形成机制和过程进行了较为深入地研究和探索，取得了以下主要成果:该边坡随着河谷下切，岩体卸荷及边坡应力场的重新分布，岩体中形成了较深的应力松弛区，主应力方向调整为重力方向，应力松弛区中陡倾的层状岩体在其作用下向河谷方向发生倾倒变形；根据物理试验特征及数值分析结果，将倾倒变形演化过程归纳为:卸荷-回弹拉裂阶段、变形-裂隙发育阶段、折断-裂隙贯通阶段。 |
| 关键词: 河谷下切 颗粒流 倾倒变形 卸荷 底摩擦 |
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| A study on mechanism and process of Yagong toppling fracture in the upper reaches of Lancang River |
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li ming, tu guo xiang, luo xin ping, shang qi
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College of Environment and Civil Engineering, Chengdu University of Technology
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| Abstract: |
| Deep-seated toppling deformation of steep stratified rock mass is a commonly-seen geological phenomenon among deeply incised valleys in Southwest China. Primarily contributing to this is severe valley downcutting, in the wake of uplift of Qinghai-Tibet Plateau since the Quaternary period. In the present paper, which case studies Yagong toppling fracture in the upper reaches of Lancang River, bottom-friction gravity test and numerical calculation were employed to delve into and probe into the mechanism and process of how such toppling fracture has formed during valley downcutting. The study has drawn conclusions mainly as follows: the side slope moved along with the valley while downcutting; rock mass loaded off and field of stress of side slope re-distributed; a deep-seated area of stress relaxation took shape in the rock mass; and direction of primary stress re-aligned with gravity direction, under the effect of which deep-seated stratified rock mass in the area of stress relaxation was made topple and deform towards the valley. The study, on the basis of physical testing features and numerical analysis results, finally concludes evolution of such toppling and deformation as the stage of unloading-rebound tension fracture, the stage of deformation-crack development, and the stage of fracture-crack penetration. |
| Key words: valley downcutting particle flow toppling deformation rock-mass unloading base friction |
