基于CT扫描技术预测露天煤矿区不同压实土壤水分特征曲线

Prediction of the soil water characteristic curve in an opencast coal mining area based on CT scanning technology

  • 摘要: 随着机械化程度的快速增加,露天煤矿区反复机械作业和废料堆积压实会引起土地资源破坏,造成土壤退化和生态失衡。厘清压实对土壤水力特性的影响,对土地复垦和水肥管理具有重要实际意义。本研究采集山西平朔矿区安太堡露天煤矿排土场的表层土壤,在实验室分别制备了2组实验土壤样品,密度范围为1.3~1.8 g/cm3,密度间隔为0.1 g/cm3。其中一组样品用于实验室离心法测定水分特征曲线,另一组基于CT扫描技术结合土壤大孔隙的三维重构技术,预测设定压实范围内的水分特征曲线。通过统计方法对比预测值和实测值的差异验证物理经验模型的预测性能,分析压实作用对土壤水分特征曲线的影响机理。结果显示,CT扫描技术快速便捷获取了土壤大孔隙的分布特征,且随着压实程度增加,土壤大孔隙数量和大孔隙度显著减少,有效降低土壤孔隙间的连接度。对于土壤水分特征曲线的预测值发现,在可预测的密度范围内,土壤含水量随着压实程度增加而迅速降低,这主要是由于压实作用改变了土壤大孔隙的分布特征,土壤内部紧缩,储水效果降低造成的,且预测值和实测值随密度的变化规律相同,模型的预测精度较高。

     

    Abstract: With the rapid increase of mechanization, the compaction caused by repeated mechanical operations and waste accumulation in open-pit coal mine areas will cause the destruction of land resources, resulting in soil degradation and ecological imbalance. Clarifying the impact of compaction on soil hydraulic characteristics is of great practical significance for land reclamation, and water and fertilizer management. In this study, the surface soil was collected from the dump of Antaibao opencast coal mine in Pingshuo mining area, Shanxi Province, and two groups of experimental soil samples were prepared in the laboratory. The bulk density range was 1.3-1.8 g/cm3,and the bulk density interval was 0.1 g/cm3. One group of samples was used to determine the water characteristic curve by centrifugation in the laboratory, and the other group was based on the CT scanning technology combined with three-dimensional reconstruction technology of soil macropores to predict the water characteristic curve within the compaction range. By comparing the difference between the predicted value and the measured value based on statistical method, the prediction performance of the physical empirical model was verified, and the influence mechanism of compaction on soil water characteristic curve was analyzed. The results showed that the CT scanning technology can quickly and easily obtain the distribution characteristics of soil macropores, and with the increase of compaction degree, the number of soil macropores and macro-porosity significantly decreases, effectively reducing the connectivity between soil pores. For the predicted value of the soil moisture characteristic curve, it is found that in the predictable range of bulk density, the soil water content decreases rapidly with the increase of compaction, which is mainly due to the compaction's alteration on the distribution characteristics of soil macropores, the internal compaction of the soil, and the reduction effect of water storage. The predicted value and the measured value vary with the bulk density in the same way, and the prediction accuracy of the model is higher.

     

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