玉树地区降水条件下潜在滑坡体位移及土壤水分变化特征研究

Characteristics of Potential Landslide Displacement and Soil Water Variation Under Precipitation Conditions in Yushu Area

基于玉树典型滑坡风险区的降雨量、土壤含水量和坡面累计位移监测数据,利用Darcy–Richards方程进行不同坡位下土壤含水量的模拟,探究降水条件下潜在滑坡体位移及土壤水分变化特征。结果表明:研究区上、下坡位不同土层深度下土壤含水量与降雨量变化趋势一致,土壤含水量变化波动随土层深度的增加而降低。降雨量多的月份上、下坡位较浅层土壤含水量均高于较深层土壤;在降雨量较少的月份,上坡位土层土壤含水量表现为30 cm<60 cm<120 cm<90 cm,下坡位土层土壤含水量表现为60 cm>30 cm>120 cm>90 cm。下坡位的垂直位移与水平位移的变化量均高于上坡位,上坡位最大垂直位移出现和结束均早于最大水平位移;下坡位垂直位移与水平位移先呈上升趋势,达到最大垂直位移累计量,而后又迅速下降。不同深度土壤水力学参数反演结果发现,随着土层深度的增加,土壤的饱和含水量和参数α明显减小,而土壤的饱和导水率Ks则随土层深度的增加而增大,土壤的参数n基本稳定。研究结果可为高原地区滑坡预报预警和风险防控提供科技支撑。

Based on the monitoring data of rainfall,soil water content and cumulative slope displacement in the typical landslide risk area of Yushu,the Darcy-Richards equation was used to simulate the soil water content under different slope positions,and explore the characteristics of potential landslide displacement and soil water change under precipitation conditions.The results show that the soil moisture content at different soil depths in the upper and lower slopes of the study area is consistent with the trend of rainfall changes,and the fluctuation of soil moisture content changes decreases with the deeper depth of the soil layer.In the months with high rainfall,the soil moisture content of the shallower soil layer was higher than that of the deeper soil layer;in the months with low rainfall,the soil moisture content of the soil layer in the upper slope was 30 cm<60 cm<120 cm<90 cm,and that of the soil layer in the lower slope was 60 cm>30 cm>120 cm>90 cm.The changes of the vertical and horizontal displacements of the lower slope were higher than that of the upper slope,and the maximum vertical displacement of the upper slope was higher than that of the upper slope.The vertical and horizontal displacements of downslope were higher than those of upslope,and the maximum vertical displacement of upslope appeared and ended earlier than the maximum horizontal displacement;the vertical and horizontal displacements of downslope firstly showed an upward trend,reached the cumulative amount of the maximum vertical displacement,and then declined rapidly.The inversion results of soil hydraulic parameters at different depths found that the saturated water content and parameterαof the soil decreased significantly with the increase of soil depth,while the saturated hydraulic conductivity Ks of the soil increased with the increase of soil depth,and the parameter n of the soil was basically stable.The results of the study can provide scientific and technological support for landslide forecasting and early warning and risk prevention and control in the plateau area.