黄土覆盖区采动地表裂缝对土壤水分扰动影响的模拟试验研究

Simulation Experiment on Effect of Surface Cracks Caused by Coal Mining on Soil Moisture Disturbance in Loess-Covered Area

[目的]探究黄土覆盖区煤矿开采沉陷变形造成的地表裂缝对土壤水分变化的扰动效应,为采煤沉陷区土壤水分变化规律研究提供数据支撑。[方法]以典型黄土覆盖区的采煤沉陷区为模型,使用自主研制的开采沉陷地表裂缝模拟装置进行物理模拟试验,并在裂缝周围布设水分传感器,分析地表裂缝引起的土壤水分变化特征。利用Hydrus软件构建水文模型,结合物理模拟试验结果对数值计算模型进行优化。采用控制变量法,利用优化后的模型计算在不同裂缝形状、地形以及初始含水量条件下裂缝周围土壤含水量与非变形区土壤含水量差值。[结果]裂缝宽度主要影响土壤水分散失量的最大值,而裂缝深度主要影响散失量最大值出现的位置;裂缝对上坡方向和下坡方向影响规律存在差异,且坡度越大,差异越明显;土壤初始含水量越小,裂缝对土壤水分扰动程度越小;当初始含水量低于20%时,地表裂缝对土壤水分的影响范围不超过15 cm。[结论]在相同边界条件下,土壤水分模拟试验结果与物理试验数据变化规律呈现一致性,利用优化后的数值计算模型可以定量地分析黄土覆盖区土壤水分对采动地表裂缝的响应特征。

[Objective] The effect of surface cracks caused by coal mining on soil moisture changes in a loess-covered area was studied in order to provide data support for the study of soil moisture changes in coal mining subsidence area.[Methods] The study was conducted in a coal mining subsidence location in a loess-covered area.A self-developed mining subsidence surface crack simulation device was used to carry out physical simulation experiments.Soil moisture sensors were set around the cracks to analyze the characteristics of soil moisture changes caused by surface cracks.Hydrus software was used to build the hydrological models and to optimize them using the results of physical simulation experiments.The control variable method was used with the optimized model to calculate the differences between soil moisture content around surface cracks and soil moisture content in non-deformation areas under different fracture shapes,topography,and initial water contents.[Results] Crack width mainly affected the maximum crack-induced soil moisture loss.Crack depth mainly affected the location of the maximum crack-induced soil moisture loss.There were differences in the influence of cracks in the uphill direction and in the downhill direction.The larger the slope was,the more obvious the differences were.The smaller the initial soil moisture content was,the smaller the soil moisture disturbance by cracks was.When the initial soil water content was less than 20%,the impact of surface cracks on soil moisture was less than 15 cm away from the crack.[Conclusion] Under the same boundary conditions,the soil moisture simulation results were consistent with the changes observed in physical experimental results.The optimized hydrological model could be used to quantitatively analyze the disturbance characteristics of soil moisture resulting from surface cracks in loess-covered areas.