采矿塌陷区微地形包气带水分运移机理研究

Ground subsidence and ground fissures caused by mining destroy the original structure of the vadose zone, change the soil moisture content and movement. In order to of land reclamation and vegetation recovery, the vadose zone soil moisture movement mechanism is need to research. Aiming at the subsidence area microtopography, the fracture characteristics, the structure of the vadose zone soil in subsidence area and ground water characteristics are measured by field testing and laboratory analysis. The micro topography is reestablished in laboratory and the numerical simulation model is built. The soil column models for sand, silt and loam are set up to determine the the soil moisture characteristic curve, unsaturated soil water diffusivity and unsaturated hydraulic conductivity for high water season, mean water season and low water season. The transformation laws of the vadose zone water movement parameters at different depths are analysed. Under artificial rainfall conditions the vadose zone soil moisture infiltration process is simulated. Through experimental analysis and numerical experiments the vadose different stages of collapse moisture migration status is established, the relationship of rainfall infiltration rate with depth is determined. Finally the vadose zone type and moisture migration law in subsidence area are obtained , and the different depths of water infiltration model subsidence area is established. The research results provide a theoretical basis for land reclamation in mining subsidence area.

地下采矿引起地面塌陷、地裂缝破坏原有矿区包气带结构，改变了包气带土壤水分含量及运移过程，为对塌陷区进行土地复垦及植被恢复，需对塌陷包气带土壤水分运移机理进行研究。项目以塌陷微地形为研究对象，结合野外试验及室内试验测定塌陷区包气带土壤结构特征、地裂缝特征及水分特征等，建立室内塌陷区微地形模型并建立数值模拟模型。分别对微地形丰水期、平水期、枯水期建立实验室土柱砂土、粉土、壤土模型，测试包气带土壤水分特征曲线、非饱和土壤水扩散率及非饱和导水率，并分析塌陷地形下不同深度的包气带水分运动参数变化规律；人工降雨模拟大雨及小雨状况下包气带土壤水分下渗过程，采用数值法对包气带土壤水分运移进行模拟，通过实验分析及数值模拟得出塌陷区的包气带水分运移状态及等效孔隙渗流力学模型。得到塌陷区包气带水分运移类型及运移规律，并建立塌陷区不同深度的水分入渗模型。研究成果为采矿塌陷区土地复垦提供一定理论依据。

采矿导致地面沉陷、地裂缝等，导致矿区下垫面条件发生变化，降雨过程中大量地表水向塌陷区汇聚或沿塌陷裂缝渗漏，地表产流过程发生变化，造成矿区降雨-入渗补给出现区域性异常，矿区降雨-入渗再分布发生变化。项目以阜新采矿塌陷区为研究对象，采用现场调研、室内试验、理论分析及数值模拟的方法对采矿裂缝条件下包气带土壤水分运移机理进行了研究，项目取得以下研究成果：（1）项目通过实地考察对塌陷裂缝进行了分类，分析了塌陷区土壤颗粒、土壤容重、土壤含水量等的时空分布特征，得到了塌陷区土壤容重、土壤含水量随塌陷裂缝的突变性；（2） 根据塌陷区土壤容重变异性，室内测定不同容重的土壤水分特征曲线，并分析了容重与孔隙、水力传导系数等的关系，为土壤水分运移模型的建立提供基础；（3）通过室内试验研究了裂缝条件的非饱和水平扩散运移试验，通过试验结果统计得到了裂缝对土壤水分水平扩散的影响； （4）采用人工降雨方式，室内搭建无裂缝和不同宽度裂缝土壤降雨-入渗试验平台，通过试验得到塌陷裂缝对降雨-入渗的再分布影响，分析了裂缝土槽中土壤含水量的空间变异性特征。（5）通过试验结果建立了土壤水分运移模型，并应用Hydrus2D、Hydrus3D模拟了塌陷裂缝条件下的土壤水分运移过程，通过实测值及模拟值的对比，验证了模型的可靠性。项目研究了塌陷裂缝条件下包气带土壤水分运移机理，揭示了塌陷区包气带土壤特征的变异过程。项目的研究不仅为保护矿区环境、矿区土壤生态修复提供一定的理论依据和技术支持，同时为非连续介质包气带土壤水分运移提供一定的研究基础。