降雨对低速滑坡形成机制的研究
|
摘要
降雨是引起黄土滑坡发生的主要原因之一,直接影响着黄土地区工程建设,制约当地经济发展。以某纪念馆基坑开挖引起其北侧老滑坡局部复活为案例,通过野外勘探,测量等手段,结合X射线衍射分析方法对滑带土进行矿物成分分析,利用Midas GTS NX软件对其进行降雨入渗数值模拟分析,利用强度折减法分析滑坡的活动机理。得出以下结论:(1)该滑坡按其运动类型可分为低速缓动滑坡,在接触面形成软弱带的双层异质是该滑坡形成的主要原因;(2)试验发现滑带土中含有较多的蒙脱石矿物,粘土中蒙脱石矿物成分会以其片状颗粒包裹在其他矿物周围并控制粘性土的强度;(3)该边坡在坡度很低的条件下仍发生滑动是由于其上部垂直裂隙发育,降雨入渗润滑了下部基岩面,增大了上覆土体的自重,并在接触吸水作用下致使滑带土的抗剪持续降低。
Rainfall is one of the main causes of loess landslide, which directly affects the project construction in loess area and restricts the local economic development. In this paper, a local old-landslide revivification in the north of a memorial hall caused by the excavation of foundation pit is taken as an example. The mineral composition of the sliding zone soil is analyzed by means of field exploration, survey and X-ray diffraction analysis. The rainfall infiltration is numerically simulated by Midas GTS NX software, and the activity mechanism of landslide is analyzed by strength reduction method. The conclusions are as follows(1) The landslide can be divided into low-speed and slowly-moving landslide according to its movement type, and what mainly causes the formation of landslide is the double-layer heterostructure of weak interbed on the contact surface,(2) It is found that there are a great amount of montmorillonite in the sliding zone soil, and, in the clay, it wraps around other minerals in a flaky and granular way, and controls the strength of the clay,(3) Why the landslide still occurs at very low slope is because upper vertical fissures develop, the lower bedrock surface is wet by the rainfall infiltration, and the weight-increased upper overlying soil absorbs the water by contact, resulting in continuous reduction of the shear resistance of the sliding zone soil.
Rainfall is one of the main causes of loess landslide, which directly affects the project construction in loess area and restricts the local economic development. In this paper, a local old-landslide revivification in the north of a memorial hall caused by the excavation of foundation pit is taken as an example. The mineral composition of the sliding zone soil is analyzed by means of field exploration, survey and X-ray diffraction analysis. The rainfall infiltration is numerically simulated by Midas GTS NX software, and the activity mechanism of landslide is analyzed by strength reduction method. The conclusions are as follows(1) The landslide can be divided into low-speed and slowly-moving landslide according to its movement type, and what mainly causes the formation of landslide is the double-layer heterostructure of weak interbed on the contact surface,(2) It is found that there are a great amount of montmorillonite in the sliding zone soil, and, in the clay, it wraps around other minerals in a flaky and granular way, and controls the strength of the clay,(3) Why the landslide still occurs at very low slope is because upper vertical fissures develop, the lower bedrock surface is wet by the rainfall infiltration, and the weight-increased upper overlying soil absorbs the water by contact, resulting in continuous reduction of the shear resistance of the sliding zone soil.
引文
[ 1 ] 李同录,龙建辉,李新生.黄土滑坡发育类型及其空间预测方法[J].工程地质学报,2007,15(4):500-505.
[ 2 ] 吴玮江,王念秦.黄土滑坡的基本类型与活动特征[J].中国地质灾害与防治学报,2002,13(2):36-40.
[ 3 ] Derbyshire E,Dijkstra T A,Smalley I J,et al.Failure Mechanisms in Loess and the Effects of Moisture Content Changes on Remoulded Strength[J].Quaternary International,1994,24:5-15.
[ 4 ] 刘伟.黄土-泥岩接触面滑坡滑带土变形特征研究[D].兰州:兰州大学,2016.
[ 5 ] 刘传成.内蒙古黄土泥岩地带界面滑坡的室内模型试验研究[D].呼和浩特:内蒙古工业大学,2014.
[ 6 ] 文宝萍,王思敬,王恩志,等.黄土-红层接触面滑坡的变形特征[J].地质学报,2005,79(1):144.
[ 7 ] González D A,Ledesma A,Corominas J.The Viscous Component in Slow Moving Landslides:A Practical Case[C]//Landslides and Engineered Slopes:From the Past to the Future.London:Taylor & Francis Group,2008,237-242.
[ 8 ] 李媛,吴奇.孟家山黄土-红层接触面滑坡破坏机理研究[J].水文地质工程地质,2001,28(1):52-54.
[ 9 ] 石瑞红.黄土-红层接触面滑坡形成演化机理[D].兰州:兰州大学,2013.
[10] 严春杰,唐辉明,孙云志.利用扫描电镜和X射线衍射仪对滑坡滑带土的研究[J].地质科技情报,2001,20(4):89-92.
[ 2 ] 吴玮江,王念秦.黄土滑坡的基本类型与活动特征[J].中国地质灾害与防治学报,2002,13(2):36-40.
[ 3 ] Derbyshire E,Dijkstra T A,Smalley I J,et al.Failure Mechanisms in Loess and the Effects of Moisture Content Changes on Remoulded Strength[J].Quaternary International,1994,24:5-15.
[ 4 ] 刘伟.黄土-泥岩接触面滑坡滑带土变形特征研究[D].兰州:兰州大学,2016.
[ 5 ] 刘传成.内蒙古黄土泥岩地带界面滑坡的室内模型试验研究[D].呼和浩特:内蒙古工业大学,2014.
[ 6 ] 文宝萍,王思敬,王恩志,等.黄土-红层接触面滑坡的变形特征[J].地质学报,2005,79(1):144.
[ 7 ] González D A,Ledesma A,Corominas J.The Viscous Component in Slow Moving Landslides:A Practical Case[C]//Landslides and Engineered Slopes:From the Past to the Future.London:Taylor & Francis Group,2008,237-242.
[ 8 ] 李媛,吴奇.孟家山黄土-红层接触面滑坡破坏机理研究[J].水文地质工程地质,2001,28(1):52-54.
[ 9 ] 石瑞红.黄土-红层接触面滑坡形成演化机理[D].兰州:兰州大学,2013.
[10] 严春杰,唐辉明,孙云志.利用扫描电镜和X射线衍射仪对滑坡滑带土的研究[J].地质科技情报,2001,20(4):89-92.