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黄河中游陕北煤矿区不同宽度的采动地裂缝对土壤抗冲性的影响

Influence of mining-induced ground fissures with different widths on soil anti-scourability in northern Shaanxi coal mining area in the middle reaches of the Yellow River

  • 摘要: 采动地裂缝作为黄河中游陕北煤矿区显著且最具代表性的采动损害形式,引发的水土流失效应已经不容忽视。为研究采动地裂缝发育对周围土壤抗冲性的影响,选取陕北柠条塔北翼采动地裂缝发育区内宽度为0~10 cm、10~20 cm、20~30 cm的采动地裂缝作为研究对象,采集其周边水平距离0~80 cm的表层土壤,测定土壤机械组成、>0.25 mm水稳性团聚体、有机质等5个国内外学者普遍关注的土壤抗冲性影响因子和土壤抗冲系数,揭示采动地裂缝周围土壤理化特性指标及抗冲系数的变化规律,构建陕北采动地裂缝发育区表层土壤抗冲系数的预测模型。结果表明:采动地裂缝周围表层土壤在冲刷作用下产生的泥沙流失量会随冲刷时间的增加呈现“速增(0~1 min)、缓增(1~3 min)、稳持(3~10 min)”3阶段的变化过程,冲刷产生的泥沙流失量主要来自于3 min以内,其贡献率超过90%;采动地裂缝会产生大幅降低周围表层土壤抗冲性的效应,最大降幅为32.1%,且采动地裂缝宽度越大,越靠近地裂缝,该效应越明显;土壤抗冲系数与砂粒质量分数呈极显著负相关(p<0.01),与黏粒、>0.25 mm水稳性团聚体、有机质质量分数呈极显著正相关(p<0.01),其中砂粒、有机质、>0.25 mm水稳性团聚体质量分数可作为陕北采动地裂缝发育区土壤抗冲性的主控因素;以采动地裂缝宽度、距裂缝水平距离为变量,构建了采动地裂缝发育区表层土壤抗冲系数预测模型,计算发现当水平距离超过158 cm时,采动地裂缝对周围表层土壤抗冲性的影响基本消失,其可作为陕北采动地裂缝发育区土壤水蚀性防控的靶向区域。研究结果可为黄河中游陕北矿区水土流失的精准防控提供科学依据。

     

    Abstract: As the most significant and representative form of mining damage in the coal mining area of northern Shaanxi in the middle reaches of the Yellow River, the soil erosion effect caused by mining ground fissures can not be ignored. In order to study the influence of mining-induced ground fissures on the anti-scourability of surrounding soil, the mining-induced ground fissures with widths of 0−10cm, 10−20 cm and 20−30 cm in the mining-induced ground fissure development area in the north wing of Ningtiaota in northern Shaanxi were selected as the research objects. The surface soil with a horizontal distance of 0−80 cm was collected, and the soil mechanical composition, >0.25 mm water-stable aggregates and organic matter were measured. Five influencing factors of soil anti-scourability and soil anti-scourability coefficient, which are generally concerned by domestic and foreign scholars, reveal the changes of soil physical and chemical properties and anti-scourability coefficient around mining-induced ground fissures. The prediction model of surface soil anti-scour coefficient in the mining ground fissure development area of northern Shaanxi was constructed. The results show that: The sediment loss caused by the erosion of the surface soil around the mining ground fissure will show a three-stage change process of “rapid increase (0−1 min), slow increase (1−3 min) and stable (3−10 min)” with the increase of the erosion time. The sediment loss caused by the erosion mainly comes from within 3 min, and its contribution rate exceeds 90%. Mining-induced ground fissures will have a significant effect on reducing the anti-scourability of the surrounding surface soil, with a maximum decrease of 32.1%, and the greater the width of the mining-induced ground fissures, the closer to the ground fissures, the more obvious the effect. The soil anti-scourability coefficient was significantly negatively correlated with the mass fraction of sand (p<0.01), and was significantly positively correlated with the mass fraction of clay, >0.25mm water-stable aggregates and organic matter (p<0.01). Among them, the mass fraction of sand, organic matter and >0.25 mm water-stable aggregates can be used as the main controlling factors of soil anti-scourability in the mining ground fissure development area of northern Shaanxi. The prediction model of surface soil anti-scourability coefficient in mining ground fissure development area is constructed by taking the width of mining ground fissure and the horizontal distance from the fissure as variables. It is found that when the horizontal distance exceeds 158 cm, the influence of mining ground fissure on the surrounding surface soil anti-scourability basically disappears, which can be used as the target area for the prevention and control of soil water erosion in the mining ground fissure development area of northern Shaanxi. The research results can provide a scientific basis for the precise prevention and control of soil erosion in the mining area of northern Shaanxi in the middle reaches of the Yellow River.

     

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