黄河中游陕北煤矿区采动地裂缝对土壤入渗特性的影响及其侵蚀效应

Influence of mining-induced ground fissures on soil infiltration characteristics and its erosion effect in coal mining area of northern Shaanxi in the middle reaches of the Yellow River

  • 摘要: 破解黄河中游煤矿区采动地裂缝的水土流失效应,对于陕北煤矿区生态环境保护与高质量发展具有重要意义。以陕北柠条塔井田北翼典型采动地裂缝发育区内宽度0~10、10~20、20~30 cm的采动地裂缝周围土壤(水平距离80 cm以内、垂直深度20 cm以浅)为研究对象,利用定水头法和仪器分析法分别测定土壤入渗速率、累积渗透量、饱和导水率(Ks)、有机质、机械组成、 > 0.25 mm水稳性团聚体含量,揭示了采动地裂缝对土壤入渗特性的影响规律,基于RUSLE2模型计算阐明了考虑入渗特性的采动地裂缝小空间尺度上的土壤侵蚀效应。结果表明:① 采动地裂缝周围土壤的入渗速率随时间变化而呈现出瞬变(0~3 min)、渐变(3~60 min)及稳定(60~110 min)3个阶段的动态变化过程;② 采动地裂缝发育提高土壤Ks的效应最显著,平均增幅为60.63%,该效应随采动地裂缝宽度的增大和距裂缝水平距离的减小而增强;③ 土壤累积入渗量和Ks与极细砂粒呈极显著正相关(p < 0.01),而与黏粒、有机质则呈极显著负相关(p < 0.01),与 > 0.25 mm水稳性团聚体也呈显著负相关(p < 0.05);④ 考虑入渗特性计算的可蚀性K值变化幅度比不考虑时放大了1.12~2.13倍;基于指数函数构建了不同宽度采动地裂缝影响周围土壤入渗速率和可蚀性K值作用范围的预测模型,发现当距采动地裂缝水平距离分别超过226、157 cm时,采动地裂缝增大周围土壤入渗速率及可蚀性的效应基本消失,其可作为黄河中游陕北黄土采动地裂缝发育区水土流失效应的精准防控靶区。

     

    Abstract: Cracking the soil and water loss effects of mining-induced surface fissures in the coal mining area of the middle reaches of the Yellow River is of great significance for ecological environment protection and high-quality development in the coal mining region of northern Shaanxi. Taking the soil around the mining-induced ground fissures with widths of 0−10, 10−20, 20−30 cm ( within 80 cm in horizontal distance and shallower than 20 cm in vertical depth ) in the typical mining-induced ground fissure development area in the north wing of Ningtiaota mine field in northern Shaanxi as the research object, the soil infiltration rate, cumulative infiltration, saturated hydraulic conductivity ( Ks ), organic matter, mechanical composition and > 0.25 mm water-stable aggregates were measured by constant head method and instrument analysis method, respectively. The influence of mining-induced ground fissures on soil infiltration characteristics was revealed. Based on the RUSLE2 model calculation, the soil erosion effect on the small spatial scale of mining-induced ground fissures considering infiltration characteristics is clarified. The results showed that:① The infiltration rate of soil around the mining-induced fissures exhibits a dynamic variation process over time, characterized by three stages: transient ( 0−3 min ), gradual ( 3−60 min ), and stable ( 60−110 min ). ②The effect of mining-induced ground fissure development on soil Ks is the most significant, with an average increase of 60.63 %. This effect increases with the increase of mining-induced ground fissure width and the decrease of horizontal distance from ground fissure. ③ Soil cumulative infiltration and Ks were significantly positively correlated with very fine sand ( p < 0.01 ), but significantly negatively correlated with clay and organic matter ( p < 0.01 ), and significantly negatively correlated with > 0.25 mm water-stable aggregates ( p < 0.05 ). ④The variation range of erodibility K-value calculated by considering infiltration characteristics is 1.12−2.13 times larger than that without considering infiltration characteristics. Based on the exponential function, the prediction model of the influence range of mining-induced ground fissures with different widths on the infiltration rate and erodibility K-value of the surrounding soil was constructed. It was found that when the horizontal distance from the mining-induced ground fissures exceeded 226 cm and 157 cm, respectively, the effect of mining-induced ground fissures on increasing the infiltration rate and erodibility of the surrounding soil basically disappeared. It can be used as a precise prevention and control target area for soil erosion in the loess mining-induced ground fissure development area in the middle reaches of the Yellow River.

     

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