甘肃舟曲牙豁口多级滑坡变形特征及复活机理

doi:10.19657/j.geoscience.1000-8527.2021.157

摘要/Abstract

摘要：

2019年7月19日,甘肃舟曲县牙豁口发生多级滑坡,该滑坡是牙豁口老滑坡中部凹槽内的复活滑动,其体积约215.5×10⁴ m³。该滑坡从斜坡体顶部崖口处启动,呈“流塑”状自上而下缓慢滑落至岷江,导致岷江河道被阻塞,水位上升,严重威胁附近居民以及下游城镇的安全。为探究该滑坡的变形特征及复活机理,本研究通过野外勘察、历史资料调研,查明了滑坡的地质环境背景与变形历史;通过对遥感解译、滑坡监测以及降雨数据等分析,探讨了滑坡的启动及演化过程,揭示了滑坡的复活机理。研究结果显示牙豁口多级滑坡的复活具有逐级加载、逐级传递应力、逐级启动的特点。滑坡的复活分为3个阶段:(1)上部滑体开始缓慢的塑性流动;(2)缓坡中部平台受到上部滑体的预压,形成“切填”效应,其破坏形式为蠕滑-拉裂-滑移;(3)下部坡体滑动。

关键词: 牙豁口滑坡, 塑性流动, 变形特征, 复活机理, 多级滑坡

Abstract:

On July 19^th, 2019, a multi-stage landslide (volume: 215.5×10⁴ m³) with a reactivated sliding in the middle groove of the paleo-landslide occurred in Yahuokou (Zhouqu County,Gansu Province). The landslide started from the cliff mouth at the top of the slope body, and slowly slid down to the Minjiang River with flow shape. This blocked the Minjiang River channel and raised the water level, seriously threatening the safety of nearby residents and downstream towns. To study the deformation characteristics and revival mechanism of the landslide, the landslide geo-environmental background and deformation history were first investigated through field survey and historical data analysis. With data interpretation on remote sensing, landslide monitoring and rainfall, the landslide initiation and evolution processes were elucidated, and the landslide revival mechanism revealed. The multistage landslide resurrection is characterized by stepwise loading, stress transfer, and initiation. The landslide revival comprises three stages: (1) the upper slide began to flow slowly in a plastic form; (2) the middle platform of the gentle slope was prepressed by the upper sliding body, forming the “cut-fill” effect. Its failure mode is creep slip-tensile crack-sliding; (3) the lower block slid.

Key words: Yahuokou landslide, plastic flow, deformation characteristic, revival mechanism, multi-stage landslide

中图分类号:

P642.22

杨校辉, 朱鹏, 袁中夏, 张卫雄, 丁保艳. 甘肃舟曲牙豁口多级滑坡变形特征及复活机理[J]. 现代地质, 2023, 37(04): 1004-1012.

YANG Xiaohui, ZHU Peng, YUAN Zhongxia, ZHANG Weixiong, DING Baoyan. Deformation Characteristics and Revival Mechanism of Yahuokou Multi-stage Landslide in Zhouqu, Gansu Province[J]. Geoscience, 2023, 37(04): 1004-1012.

图/表 14

图1 甘肃舟曲牙豁口滑坡位置[19]

Fig.1 Location of the Yahuokou landslide in Zhouqu, Gansu Province [19]

图2 2019年舟曲县降雨量分布

Fig.2 Monthly rainfall histogram of Zhouqu County in 2019

图3 牙豁口滑坡遥感影像及剖面图[19] (a) 滑坡全貌遥感影像图;(b) 滑坡1-1'工程地质剖面图

Fig.3 Remote sensing image and profile of the Yahuokou landslide [19]

图4 牙豁口滑坡及周边大型滑坡发育分布图[8] 1.全新统;2.中上更新统;3.中二叠统;4.下二叠统;5.下石炭统;6.上泥盆统铁山组;7.中泥盆统古道岭组上段;8.中泥盆统古道岭组下段;9.中上志留统白龙江群上段;10.中上志留统白龙江群中段;11.中上志留统白龙江群下段;12.断裂;13.泥石流;14.滑坡;15.河流;16.三叠系

Fig.4 Development and distribution of the Yahuokou landslide and its surrounding large-scale landslides [8]

图5 牙豁口滑坡滑动过程遥感影像图[19]

Fig.5 Remote sensing image of the Yahuokou landslide sliding process[19]

图6 滑坡滑动堆积至宽缓的平台上部

Fig.6 Field photo showing the landslide slides up to the top of the broad, gentle platform

图7 滑体呈“土石流”状沿陡坡向下滑动

Fig.7 Field photo showing the sliding body slides down the steep slope in the form of rock flow

图8 滑坡滑动后拉伸形成的大“V”形拉槽

Fig.8 Field photo showing large V-shaped groove formed by stretching after landslide

图9 滑坡体变形迹象

Fig.9 Field photo showing features of landslide deformation

图10 2019年7月19日滑坡后滑体各部分遥感示意图[19] (a)中级滑体、下级滑体运动模式遥感影像示意图; (b)滑体前缘扇形地侵入岷江河道遥感示意图

Fig.10 Remote sensing diagram of each part of the sliding body after July 19th, 2019[19]

图11 现场岩心取样图片

Fig.11 Field photo showing core sampling

表1 岩土体物理力学参数

Table 1 Physico-mechanical parameters of rock and soil mass

滑体部位	含水率 (%)	天然重度 (kN/m³)	黏聚力 (kPa)	内摩擦角 (°)	塑性指数 (%)
上层	8.2	19.7	14.19	17.10	10.73
下层	7.2	19.4	5.08	14.38	11.90

图12 滑坡滑速监测及区域降雨数据[19]

Fig.12 Data plot of landslide velocity monitoring and regional rainfall [19]

图13 滑坡复活各阶段示意图

Fig.13 Profile for each stage of the landslide revival

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