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    斜坡单元支持下基于土体含水率的陕西省清涧县城区黄土滑坡危险性评价

    Hazard assessment of loess landslide based on soil moisture content and supported by slope unit in Qingjian City, Shaanxi Province

    • 摘要: 滑坡危险性评价是减灾防灾的重要措施之一。通过野外调查,陕西省清涧县城区周边斜坡地带共发育滑坡138处,严重威胁县城安全。为了准确评价清涧县城区滑坡危险性,按照河流沟谷的发育情况和地形地貌的完整性,将清涧县城区及周边区域的斜坡地带共划分为925个斜坡单元,将斜坡单元按照不同的坡度、坡高和坡型分别进行不同土体含水率工况下的斜坡稳定性计算。计算结果表明,随着斜坡土体含水率的逐渐增加,城区内稳定斜坡的面积逐渐减少,不稳定斜坡的面积逐渐增大。依据陕北地区黄土斜坡土体含水率监测数据,分析计算土体含水率(w)的出现概率,w≤0.15出现的概率为0.622(概率很高),0.15 < w≤0.2出现的概率为0.2963(概率高),0.2 < w≤0.25出现的概率为0.0816(概率中),w>0.25出现的概率为0(概率低)。结合斜坡稳定性计算结果和含水率出现概率,评价斜坡单元危险性。评价结果表明,清涧县城区危险性很高区面积3.27 km2,包含斜坡单元112个,已发生滑坡点92个;危险性高区面积4.19 km2,包含斜坡单元128个,已发生滑坡点36个;危险性中区面积8.75 km2,包含斜坡单元251个,已发生滑坡点6个;危险性低区面积15.20 km2,包含斜坡单元434个,已发生滑坡点4个。

       

      Abstract: Landslide hazard assessment is one of the important measures for disaster reduction and prevention. Field investigations show that 138 landslides are developed along the slopes around the city area in Qingjian, which seriously threaten the safety of the city. In order to accurately evaluate the hazard of landslides in Qingjian City, the authors divided the slope zone of Qingjian City and surrounding areas into 925 slope units according to the development of river valleys and the integrity of topography. The slope units were calculated according to different slope gradients, slope heights and slope patterns under different soil moisture values. The calculation results show that, with the gradual increase of the soil moisture content of slope, the area of the stable slope gradually decreases, and the area of the unstable slope gradually increases. According to the monitoring data of soil moisture content of loess slope in northern Shaanxi, the probabilities of occurrence of soil moisture content (w) were analyzed and calculated. The probability of occurrence of w ≤ 0.15 is 0.622 (very high probability), that of 0.15 < w ≤ 0.2 is 0.2963 (high probability), that of 0.2 < w ≤ 0.25 is 0.0816 (medium probability), and that of w>0.25 is 0 (low probability). The hazards of slope units were assessed in combination with the slope stability calculation results and the soil moisture content occurrence probability. The assessment results show that the very high hazard area is 3.27 km2, which includes 112 slope units and 92 landslides; the high hazard area is 4.19km2, which includes 128 slope units and 36 landslides; the medium hazard area is 8.75 km2, which includes 251 slope units and 6 landslides; the low hazard area is 15.20km2, which includes 434 slope units and 4 landslides.

       

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