流态型滑坡破坏前兆及破坏运移机理研究

发布时间：2018-05-07 00:31

本文选题：流态型滑坡 + 前兆分析　；参考：《成都理工大学》2017年硕士论文

【摘要】：汶川地震破坏能力强,在西南山区引发了大量的崩塌,滑坡等灾害,数量多,分布广,破坏程度大,其中滑坡、崩塌形成的堆积物块度大,细粒碎屑物多,分布面积广,常堆积于沟道中,在降雨及河流补给中很容易形成二次滑坡和泥石流。本文以文家沟松散堆积体为研究对象,主要通过室内水槽物理模拟实验对了流态型滑坡的破坏前兆及破坏运移机理进行了研究,为以后的研究提供一定的经验。本文中对松散堆积体材料进行了三轴、渗透、沉降实验,在这之后进行了降雨条件下的松散堆积体实验,考虑了不同细粒含量和不同流域面积对松散堆积体的影响。主要研究成果如下:(1)在降雨条件下,流态型滑坡机理主要经历以下几个阶段:(a)上层松散堆积体在降雨条件下,由于雨水的入渗及上层土体初期的垮塌、滑动会使下部土体压实。(b)随着降雨时间的增长,在松散堆积体内部饱和度的增加,其内部饱和区域会有微小的剪切。(c)在压缩剪切区域会引起超孔隙水压力继而引起快速剪切形成流态型滑坡。(2)对于流态型滑坡,无论在降雨还是后缘地下水上升,滑坡滑动前内部孔隙水压力缓慢上升,在流态型滑坡突然滑动前土体内部水位会保持一个平稳的阶段,土体内部位移计的监测发现,前期内部有微小变化,而大位移主要发生在流态型滑动阶段,细部还发现流态型滑动阶段主要经历了加速、匀速、减速的阶段,其加速度变化相对比较大。(3)通过微震信号的监测发现两者在滑动前震动信号都会有明显的变化,震动信号主要集中在IMF1阶段,通过HHT转化,可以看到滑坡体内部结构的调整,尤其是通过声发射可以发现在水进入水槽后和滑动前随着时间的发展信号越来越明显,细颗粒内部结构调整也越来越剧烈;试验后通过分析水槽各部位的颗粒级配分析,可以得出细颗粒在粗颗粒间有迁移现象。(4)对于不同有效降雨面积的不同细粒含量的降雨实验破坏过程可以看到,在细粒含量为0%时,有效降雨面积对松散堆积体没有影响,都没有滑动,当细粒含量超过16%时,有效降雨面积较小时表现为多级后退式滑动破坏进而转化为大块流态型滑动,而有效面积较大(工况二)在细粒含量为8%时就开始表现为整体性流态型滑坡,细粒含量为25%时先表现为坡体表面侵蚀,接着转化为流态型滑坡。说明细粒含量和有效降雨面积对流态型滑坡都有一定的影响。(5)随着细粒含量的增大,松散堆积体流态型滑动启动时间呈现先减小后增大趋势,在细粒含量为16%滑坡启动时间最短;随着细粒含量的增加,滑动距离也相应的增大,且有效降雨面积越大,滑动距离相应越远。但松散堆积体的在坡脚处下滑堆积方量在细粒含量为16%变现为最大。(6)在流态型滑坡滑动时同一位置超孔隙水压力值可以看出,细粒含量越大,滑动时形成的超孔隙水压力也越大,有效降雨面积越大,超孔隙水压力也越大。震动信号产生的高频部分却随着细粒含量的增加而减小,有效降雨面积越大,产生的震动能量越大。(7)细粒含量对于松散堆积体的液化影响并不是单调的,当没有细粒时,松散堆积体没有滑动,当细粒含量较小时,主要起到润滑的作用且会促进孔隙水压力的增长,松散堆积体更容易发生流态型滑坡,当细粒含量超过一定的值时,主要起到颗粒胶结的作用,发生泥石流的现象较大。
[Abstract]:Wenchuan earthquake has a strong destructive ability. In the southwest mountain area, a large number of landslides, landslides and other disasters are caused by a large number of landslides, widely distributed, and great damage degree, among which landslides and landslides have large accumulation blocks, many fine grained debris and a wide distribution area, and two landslides and debris flows are easily formed in the rainfall and river recharge. Taking the loose accumulation body of the Wen Jia Gou as the research object, the damage precursor and failure mechanism of the flow type landslide are studied by the physical simulation experiment of the chamber water trough, and some experience is provided for the later research. In this paper, the three axis, infiltration and settlement experiments of the loose material are carried out, and the rain strip is carried out after this. The influence of different fine grain content and different basin area on loose accumulation body is considered. The main research results are as follows: (1) under rainfall conditions, the mechanism of flow type landslides mainly experienced the following stages: (a) under rainfall conditions, the collapse of the upper layer of the upper layer of rain and the collapse of the upper soil soil at the initial stage of rainfall. Collapse, sliding will make the lower soil compacted. (b) with the increase of rainfall time, the inner saturation area will have small shear in the inner saturation area. (c) the excess pore water pressure in the compression shear zone will cause the rapid shear to form the flow pattern landslides. (2) for the flow type landslides, whether in the rainfall or after the flow type landslides. The internal pore water pressure of the internal water increases slowly before the slide of the landslide, and the internal water level of the soil will keep a stable stage before the slide slide. The monitoring of the internal displacement meter finds that there is a slight change in the early stage, and the large displacement mainly occurs in the flow state sliding stage, and the flow pattern is also found in the detail. The segment mainly experienced the stage of acceleration, uniform speed and deceleration. (3) through the monitoring of the microseismic signal, it is found that the vibration signals of both before sliding will have obvious changes, the vibration signals are mainly concentrated in the IMF1 stage, and the internal structure adjustment of the landslide body can be seen through the transformation of HHT, especially by acoustic emission. It is found that the internal structure adjustment of fine particles is becoming more and more dramatic after the water entering the water trough and the development of the time before sliding. After the analysis of the grain gradation analysis of the various parts of the tank, the migration of fine particles in the coarse particles can be obtained. (4) the different fine grain content for different effective rainfall areas When the fine grain content is 0%, the effective rainfall area has no effect on the loose accumulation body, and there is no sliding. When the fine grain content exceeds 16%, the effective rainfall area is a multistage backward sliding failure and then turns into a large mass flow type sliding, and the effective area is larger (two) in fine grain. When the amount is 8%, it begins to show as a holistic flow type landslide. The fine particle content is 25% when the slope surface erosion first, and then into the flow type landslide. It shows that the fine grain content and the effective rainfall area have a certain influence on the flow pattern landslides. (5) with the increase of the fine grain content, the slip starting time of the loose accumulation body flow pattern is first presented. When the fine grain content is 16%, the starting time of the landslide is the shortest, and the sliding distance increases with the increase of the fine grain content, and the larger the area of the effective rainfall is, the farther the sliding distance is, but the maximum of the slipping accumulation at the foot of the slope at the foot of the slope is the largest in the fine grain content of 16%. (6) when the slide type slide is slipping The excess pore water pressure in the same position shows that the larger the fine grain content is, the greater the excess pore water pressure is, the greater the effective rainfall area is, the greater the excess pore water pressure is. The higher the high frequency part of the vibration signal decreases with the increase of the fine grain content, the greater the area of the effective rainfall is, the greater the vibration energy is. (7) fine particles. The effect of content on the liquefaction of loose accumulation body is not monotonous. When there is no fine particles, the loose accumulation body does not slide. When the fine grain content is small, it is mainly lubricated and will promote the increase of pore water pressure. The loose accumulation body is more prone to flow pattern landslides. When the fine grain content exceeds a certain value, it mainly plays the particles. The effect of cementation is the phenomenon of debris flow.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.22

【参考文献】