To study the influence of coal mining on the porosity of shallow sandy loam under conditions of shallow seam mining in thick, loose layers in north-west China, a typical surface sandy loam stratum in Shaanxi Province was taken as the study area, and experiments were performed to test the variation of soil porosity at different depths of 0–10 m in strata before, during and after mining therein. The experimental results demonstrate that the overall average porosities in the disc-shaped edge area, the disc-shaped edge area to the disc-shaped basin bottom area and the disc-shaped subsidence centre area of shallow sandy loam in mining increased by (23.51, 18.07 and 22.61%) respectively compared with that before mining. Mining meant that the soil porosity in the period of stable subsidence after mining changed significantly in the disc-shaped edge area and the disc-shaped edge to the disc-shaped basin bottom area. The disc-shaped edge area shows a trend of slowly rising porosity with the increase of depth, and the disc-shaped edge area to the disc-shaped basin bottom area shows a trend of gradually increasing first and then gradually becoming stable. Although the porosity in the central area of disc-shaped subsidence increased before mining, its trend was similar to that before mining. Although the change in soil porosity in the period of post-mining settlement stability is greater than that before mining, it is best fitted by a quintic polynomial. In general, the rate of change of soil porosity in the study area shows similar trends with depth. It showed a U-shaped variation that first decreased, stabilised for a distance and then gradually increased. This study provides theoretical support for surface soil remediation and ecological environment restoration in coal mining areas.

中文翻译：

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浅层煤层开采影响下西北地区浅层砂壤土孔隙度变化

为研究在西北厚层松散层浅煤层开采条件下煤炭开采对浅层砂壤土孔隙度的影响，以陕西省典型地表砂壤土地层为研究区，进行了试验。用于测试地层开采前、开采中和开采后 0-10 m 不同深度土壤孔隙度的变化。试验结果表明，开采中浅砂壤土的盘状边缘区、盘状边缘区至盘状盆地底部区域和盘状沉陷中心区的总体平均孔隙度增加了(23.51, 18.07% 和 22.61%) 与开采前相比。开采是指开采后稳定沉降期的土壤孔隙度在盘状边缘区域和盘状边缘到盘状盆地底部区域发生显着变化。盘形边缘区域随着深度的增加孔隙度呈现缓慢上升的趋势，盘形边缘区域向盘形盆底区域呈现先逐渐增加后逐渐趋于稳定的趋势。盘状沉降中心区的孔隙度虽然在开采前有所增加，但其趋势与开采前相似。尽管开采后沉降稳定期土壤孔隙度的变化大于开采前，但最好用五次多项式拟合。总体而言，研究区土壤孔隙度变化率随深度变化趋势相似。呈U型变化，先减小，稳定一段距离，然后逐渐增大。该研究为煤矿区表层土壤修复和生态环境恢复提供理论支持。