宝鸡黄土梁地区不稳定边坡的滑坡机制及预警

发布时间：2018-08-20 12:26

【摘要】：我国西北黄土高原地区黄土滑坡具有较高的发生频率,滑坡地质灾害由于其对人类可造成巨大的损失而成为关注性较高的事件。水文地质条件、水文地质参数、降雨及地下水的入渗补给特征对于浅层黄土边坡稳定性有着较大的影响作用。因此,准确掌浅层黄土的特性对于预防及治理浅层黄土滑坡具有较高的指导意义和实际应用价值。研究区位于陕西宝鸡市渭河南岸、秦岭山前的黄土丘陵区。本次研究中进行了黄土边坡稳定性控制因素的调查,重点研究了水文地质参数及降雨入渗对边坡稳定性的影响。建立了地下水流模型获取了整个研究区分布式水文地质参数,结合其它水力学参数和介质的工程性质参数,建立了黄土边坡稳定性预警模型,并预测了不同降雨条件边坡的稳定性。论文主要取得了以下成果:(1)研究区较陡的现代地形为滑坡提供了临空条件,黄土为滑坡提供了介质条件,黄土下覆的坡度很陡的三门组含砂、泥岩充当滑动层,强度较大、持续时间长或频率较大的降雨导致地下水位快速上升是滑坡的诱发因素。区内滑坡为受古地形控制、降雨诱发的边坡浅层黄土滑坡。(2)研究区含水层垂向渗透系数为0.15 m/d左右,而水平渗透系数为0.014 m/d左右,渗透系数存在着明显的各向异性。建立了研究区地下水流数值模型,获得了区内分布式水文地质参数。(3)考虑到研究区降雨为诱发滑坡的主要因素,因此滑坡预警模型选用了由Baum等人提出的以区域性降雨入渗和DEM为基础的边坡的稳定性评价模型,即TRIGRS。为了使预警模型准确可靠,本次模型以2014年9月由降雨诱发的滑坡为基础,对预警模型进行了验证校准。(4)滑坡预警模型预测结果显示,当一次降雨量为50mm时不发生滑坡,当一次降雨量为100mm时发生滑坡,且随着降雨强度增加,安全系数趋于变小,滑坡的发生部位为滑坡体上的两处陡坎处及滑坡体后缘,这与观测的滑坡历史上发生的部位基本一致。
[Abstract]:Loess landslides in the Loess Plateau of Northwest China have a high frequency of occurrence, and the landslide geological hazard has become a high concern event because it can cause huge losses to human beings. Hydrogeological conditions, hydrogeological parameters, rainfall and groundwater infiltration and recharge characteristics have great influence on the stability of shallow loess slope. Therefore, it is of high guiding significance and practical application value to prevent and treat shallow loess landslide by accurately controlling the characteristics of shallow loess. The research area is located on the south bank of Weihe River in Baoji City, Shaanxi Province, in the loess hilly area in front of Qinling Mountains. In this study, the factors controlling the stability of loess slope were investigated, and the influence of hydrogeological parameters and rainfall infiltration on slope stability was studied. The groundwater flow model is established to obtain the distributed hydrogeological parameters in the whole study area. Combined with the other hydraulic parameters and the engineering property parameters of the medium, the early warning model of loess slope stability is established. The stability of slope under different rainfall conditions is predicted. The main achievements of this paper are as follows: (1) the steep modern topography in the study area provides the conditions for the landslide, the loess provides the medium condition for the landslide, the slope of the loess is steep, the Sanmen formation contains sand, the mudstone acts as the sliding layer, and the strength is high. The rapid rise of groundwater level caused by long duration or high frequency rainfall is the inducing factor of landslide. The landslide in the study area is controlled by paleotopography and rainfall induced shallow loess landslide. (2) the vertical permeability coefficient of the aquifer is about 0.15 m / d, while the horizontal permeability coefficient is about 0.014 m / d, and the permeability coefficient has obvious anisotropy. The numerical model of groundwater flow in the study area is established, and the distributed hydrogeological parameters are obtained. (3) considering that rainfall is the main factor that induces landslides in the study area, Therefore, the landslide early warning model is based on regional rainfall infiltration and DEM, which is proposed by Baum et al. In order to make the early warning model accurate and reliable, the early warning model is validated and calibrated on the basis of the landslide induced by rainfall in September 2014. (4) the prediction results of the early warning model show that no landslide occurs when the rainfall is 50mm. When the rainfall is 100mm, the landslide occurs, and with the increase of rainfall intensity, the safety factor tends to decrease. The landslide occurs at the two steep ridges on the landslide and the rear edge of the landslide. This is basically consistent with the site observed in the history of the landslide.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.22

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