Exploring water migration patterns in reconstructed soil layers for waste dumps of open-pit coal mines based on CT scanning

Authors

• FAN Tingyu, State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Anhui University of Science & Technology, Huainan 232001, China; School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China; Key Laboratory of Xinjiang Coal Resources Green Mining, Ministry of Education, Xinjiang Institute of Engineering, Urumqi 830023, ChinaFollow
• ZHANG Xinghui, State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Anhui University of Science & Technology, Huainan 232001, China; School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China
• LU Akang, State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Anhui University of Science & Technology, Huainan 232001, China; School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China
• YANG Changde, Key Laboratory of Xinjiang Coal Resources Green Mining, Ministry of Education, Xinjiang Institute of Engineering, Urumqi 830023, China
• WANG Shun, State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Anhui University of Science & Technology, Huainan 232001, China; School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China
• WANG Xingming, State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Anhui University of Science & Technology, Huainan 232001, China; School of Earth and Environment, Anhui University of Science & Technology, Huainan 232001, China
• SUN Xueliang, Xinjiang Energy Chemical Co., Ltd., CHN Energy, Urumqi 830040, China
• JI Quancai, Key Laboratory of Xinjiang Coal Resources Green Mining, Ministry of Education, Xinjiang Institute of Engineering, Urumqi 830023, China

Abstract

Objective In the arid regions of western China, the ecological restoration of waste dumps within open-pit coal mines plays a key role in green mine construction, while creating a suitable soil profile structure serves as a prerequisite for the ecological restoration.Methods This study investigated the reconstructed soils with a three-layer sponge-like structure consisting of the topsoil, sandy-soil, and mudstone layers for the waste dump of the Hongshaquan open-pit coal mine in Xinjiang. Using computed tomography (CT) scanning, a three-dimensional (3D) pore network model (PNM), and water migration simulation, this study systematically analyzed the pore structures and water migration characteristics of various soil layers reconstructed and their transition zones.Results and Conclusions The reconstructed soil profile consisting of a 40-cm-thick topsoil layer, a sandy-soil layer with a thickness of 60 cm, and a 20-cm-thick mudstone layer exhibited the highest water-holding capacity. In this profile, the sandy-soil layer showed a favorable porosity of 27.85% and a high pore connectivity of 99.88%, with a uniform pore distribution and high hydraulic conductivity. In contrast, the topsoil layer demonstrated roughly prolate pores, with pore throats showing higher vertical permeability. As a result, localized preferential flow was prone to form. The transition zones between various soil layers demonstrated significant barrier effects due to differences in stacking and abrupt changes in texture. Specifically, a weakly permeable layer was formed in the transition zone between the topsoil and sandy-soil layers, while cavities with thicknesses ranging from 0.5 mm to 1.0 mm occurred in the transition zone between the sandy-soil and mudstone layers due to differential swelling and shrinkage. Therefore, water stagnation zones were formed in the transition zones, thus enhancing the water storage capacity. The hydraulic conductivity of various reconstructed soil layers and their transition zones decreased in the order of the sandy-soil layer, the transition zone between the topsoil and sandy-soil layers, the topsoil layer, and the transition zone between the sandy-soil and mudstone layers. The water migration in the reconstructed soil profile was jointly influenced by the microscopic morphology, interconnectivity, and orientations of pores. The results of this study reveal the differentiation patterns of pore structures and water migration characteristics in the reconstructed soils at the microscopic scale, providing a theoretical basis for the ecological restoration of open-pit coal mines in arid regions.

Keywords

waste dump in an open-pit coal mine, soil reconstruction, computed tomography (CT) scanning, microscopic pore structure, pore network model (PNM), water migration simulation

DOI

10.12363/issn.1001-1986.25.11.0872

Recommended Citation

FAN Tingyu, ZHANG Xinghui, LU Akang, et al. (2026) "Exploring water migration patterns in reconstructed soil layers for waste dumps of open-pit coal mines based on CT scanning," Coal Geology & Exploration: Vol. 54: Iss. 4, Article 12.
DOI: 10.12363/issn.1001-1986.25.11.0872
Available at: https://cge.researchcommons.org/journal/vol54/iss4/12

Reference

[1] 孙勇凯,罗西,王登甲,等. 西北地区能源生产消费特征与发展路径研究[J]. 中国工程科学,2022,24(6):38−51

SUN Yongkai,LUO Xi,WANG Dengjia,et al. Energy production and consumption characteristics and energy development path in northwest China[J]. Strategic Study of CAE,2022,24(6):38−51

[2] 卞正富,张益东,王猛,等. 新疆煤炭资源开发潜力与开发策略[J]. 煤炭学报,2024,49(2):967−977

BIAN Zhengfu,ZHANG Yidong,WANG Meng,et al. Research on the potential and strategy for coal resources exploitation in Xinjiang[J]. Journal of China Coal Society,2024,49(2):967−977

[3] 霍超. 新疆煤炭资源分布特征与勘查开发布局研究[J]. 中国煤炭,2020,46(10):16−21

HUO Chao. Research on distribution characteristics and exploration and development layout of coal resources in Xinjiang[J]. China Coal,2020,46(10):16−21

[4] 赵浩雷,张锦. 我国露天煤矿空间分布特征分析及可视化平台构建[J]. 中国煤炭,2022,48(12):9−15

ZHAO Haolei,ZHANG Jin. Analysis of spatial distribution characteristics and construction of visualization platform of open–pit coal mines in China[J]. China Coal,2022,48(12):9−15

[5] 彭苏萍,毕银丽. 西部干旱半干旱煤矿区生态环境损伤特征及修复机制[J]. 煤炭学报,2024,49(1):57−64

PENG Suping,BI Yinli. Properties of ecological environment damage and their mechanism of restoration in arid and semi–arid coal mining area of western China[J]. Journal of China Coal Society,2024,49(1):57−64

[6] 杜俊,侯克鹏,熊治茗,等. 排土场土石混合体分形特征与抗剪强度特性研究[J]. 地质与勘探,2023,59(2):377−386

DU Jun,HOU Kepeng,XIONG Zhiming,et al. Fractal characteristics and shear strength of soil–rock mixtures in waste dump[J]. Geology and Exploration,2023,59(2):377−386

[7] 毕银丽,彭苏萍,杜善周. 西部干旱半干旱露天煤矿生态重构技术难点及发展方向[J]. 煤炭学报,2021,46(5):1355−1364

BI Yinli,PENG Suping,DU Shanzhou. Technological difficulties and future directions of ecological reconstruction in open pit coal mine of the arid and semi–arid areas of western China[J]. Journal of China Coal Society,2021,46(5):1355−1364

[8] 毕银丽,杨伟,柯增鸣,等. AMF–玉米联合对“表土层–含水层–隔水层”排土场重构模式土壤水盐分布的影响[J]. 煤田地质与勘探,2023,51(4):68−75

BI Yinli,YANG Wei,KE Zengming,et al. Effect of AMF–maize combination on water and salt distribution in soil under the dump reconstruction mode of “topsoil–aquifer–aquitard”[J]. Coal Geology & Exploration,2023,51(4):68−75

[9] 毕银丽,李中庆,柯增鸣,等. 排土场土层重构与接菌对植物水分利用的影响机制[J]. 煤田地质与勘探,2025,53(10):23−32

BI Yinli,LI Zhongqing,KE Zengming,et al. Influence mechanisms of soil layer reconstruction and fungal inoculation on plant water use in waste dumps[J]. Coal Geology & Exploration,2025,53(10):23−32

[10] 毕银丽,谯寅初,彭苏萍,等. 干旱半干旱煤矿区重构土层水盐空间分布及微生物修复效应[J]. 煤炭科学技术,2026,54(1):475−485

BI Yinli,QIAO Yinchu,PENG Suping,et al. Spatial distribution of water and salt in soil layer and microbial remediation effect of reconstructed soil layer in quasi–energy dump site[J]. Coal Science and Technology,2026,54(1):475−485

[11] 刘庚辰,柯增鸣,毕银丽. 接菌对煤矸石重构土层结构的水盐分布及苜蓿生长的影响[J]. 水文地质工程地质,2025,52(4):50−61

LIU Gengchen,KE Zengming,BI Yinli. Effect of inoculation on water and salt distribution and alfalfa growth of coal gangue reconstructed layer[J]. Hydrogeology & Engineering Geology,2025,52(4):50−61

[12] 刘敏娜,解琳琳,毕银丽. 新疆红沙泉矿区盐地碱蓬根系深色有隔内生真菌的分离及其耐盐效应[J]. 菌物学报,2026,45(2):250139

LIU Minna,XIE Linlin,BI Yinli. Isolation and salt tolerance responses of dark septate endophytes in Suaeda salsa roots in Hongshaquan mining area,Xinjiang,northwest China[J]. Mycosystema,2026,45(2):250139

[13] 马力,王晓民,张奇峰,等. 干旱区露天矿外排土场隔水层重构材料试验研究[J]. 煤炭科学技术,2024,52(5):345−353

MA Li,WANG Xiaomin,ZHANG Qifeng,et al. Experimental study on reconstruction material of impervious layer in open–pit mine external dump in arid area[J]. Coal Science and Technology,2024,52(5):345−353

[14] 马力,薛飞,毕银丽,等. 干旱区露天煤矿外排土场重构包气带上层滞水毛细作用机制[J]. 煤炭学报,2023,48(增刊1):233−240

MA Li,XUE Fei,BI Yinli,et al. The outer drainage field of the open–pit coal mine in arid area reconstructs the mechanism of action of the upper layer of the gas–laden belt[J]. Journal of China Coal Society,2023,48(Sup.1):233−240

[15] 张子光,薛飞,李海潮,等. 干旱区外排土场表土毛细试验研究[J]. 煤炭工程,2021,53(11):71−75

ZHANG Ziguang,XUE Fei,LI Haichao,et al. Capillary test of topsoil in external dump of arid area[J]. Coal Engineering,2021,53(11):71−75

[16] WANG Shufei,CAO Yingui,GENG Bingjin,et al. Succession law and model of reconstructed soil quality in an open–pit coal mine dump of the loess area,China[J]. Journal of Environmental Management,2022,312:114923.

[17] LI Hairu,LIU Gang,DAN Chenxi,et al. Effects of soil porosity on water stability of aggregates[J]. Soil and Tillage Research,2025,254:106741.

[18] 许智隼,胡五龙. 基于三维X–CT图像的结皮土壤孔隙结构特征与渗透率[J]. 农业工程学报,2021,37(14):89−97

XU Zhisun,HU Wulong. Characteristics of pore structure and permeability in soil crust using 3D X–CT images[J]. Transactions of the Chinese Society of Agricultural Engineering,2021,37(14):89−97

[19] ZHANG Zihan,LI Changdong,YE Yang. Meso–structural evolution and erosion mechanisms of soil–structure interface explored via in–situ CT scanning[J]. Journal of Hydrology,2025,658:133128.

[20] 张靖,陈琳,周虎,等. 基于数字图像技术的土壤孔隙结构定量研究进展[J]. 土壤,2023,55(1):21−29

ZHANG Jing,CHEN Lin,ZHOU Hu,et al. Quantification of soil pore structure based on digital image technology:A review[J]. Soils,2023,55(1):21−29

[21] LIU Bo,FAN Haoming,HAN Wei,et al. Linking soil water retention capacity to pore structure characteristics based on X–ray computed tomography:Chinese Mollisol under freeze–thaw effect[J]. Geoderma,2021,401:115170.

[22] WANG Shengfu,LYU Liang,XUE Kaixi,et al. Micropore structure and fractal characteristics of clays due to freeze–thaw and compression based on mercury intrusion porosimetry[J]. Frontiers in Earth Science,2022,10:851673.

[23] BRYK M,KOŁODZIEJ B. Suitability of image analysis in evaluating air and water permeability of soil[J]. Agronomy,2021,11(9):1883.

[24] 申志福,孙天佑,白宇帆,等. 基于电镜成像原理的黏土微结构参数提取方法[J]. 岩土工程学报,2021,43(5):933−939

SHEN Zhifu,SUN Tianyou,BAI Yufan,et al. Extraction method for micro–structure parameters of clay based on imaging principles of scanning electron microscope[J]. Chinese Journal of Geotechnical Engineering,2021,43(5):933−939

[25] 李保国,周虎,王钢,等. 探索“透明”土壤体:土壤孔隙学的时代已经启航[J]. 土壤学报,2023,60(5):1221−1230

LI Baoguo,ZHOU Hu,WANG Gang,et al. Explore the “transparent” soils:Soilporelogy has sailed[J]. Acta Pedologica Sinica,2023,60(5):1221−1230

[26] 孟晨,牛健植,余海龙,等. 土壤大孔隙三维特征影响因素和测定方法研究进展[J]. 北京林业大学学报,2020,42(11):9−16

MENG Chen,NIU Jianzhi,YU Hailong,et al. Research progress in influencing factors and measuring methods of three–dimensional characteristics of soil macropores[J]. Journal of Beijing Forestry University,2020,42(11):9−16

[27] DANESHIAN B,HABIBAGAHI G,NIKOOEE E. Determination of unsaturated hydraulic conductivity of sandy soils:A new pore network approach[J]. Acta Geotechnica,2021,16(2):449−466.

[28] GERKE K M,KHIREVICH S,VASILYEV R V,et al. Soil hydraulic properties derived from pore–scale simulations:Digital assessment of K_sat through model intercomparison and verification with experimental data[J]. Soil and Tillage Research,2026,255:106790.

[29] IRAJI S,DE ALMEIDA T R,MUNOZ E R,et al. The impact of heterogeneity and pore network characteristics on single and multi–phase fluid propagation in complex porous media:An X–ray computed tomography study[J]. Petroleum Science,2024,21(3):1719−1738.

[30] MOTLAGH N M,KHOSHGHALB A,KHALILI N. Pore–scale simulation of soil water retention curves using DEM–derived pore networks[J]. Computers and Geotechnics,2026,189:107625.

[31] 李华焜,郑刘根,陈永春,等. 基于CT扫描的重构土壤孔隙结构及其对水盐运移影响[J]. 煤田地质与勘探,2024,52(4):120−127

LI Huakun,ZHENG Liugen,CHEN Yongchun,et al. Exploring the pore structure of reconstructed soils and its effects on water and salt transport based on CT scanning[J]. Coal Geology & Exploration,2024,52(4):120−127

[32] 邵芳,胡振琪,王培俊,等. 基于黄河泥沙充填复垦采煤沉陷地覆土材料的优选[J]. 农业工程学报,2016,32(增刊2):352−358

SHAO Fang,HU Zhenqi,WANG Peijun,et al. Selection of alternative soil for filling reclamation with Yellow River sediment in coal–mining subsidence areas[J]. Transactions of the Chinese Society of Agricultural Engineering,2016,32(Sup.2):352−358

[33] 冯正江,聂卫波,余淼,等. 多尺度土壤入渗特性的变异特征和传递函数构建[J]. 农业工程学报,2022,38(13):64−75

FENG Zhengjiang,NIE Weibo,YU Miao,et al. Multiple scale variability of soil infiltration characteristics and establishment of pedo–transfer function[J]. Transactions of the Chinese Society of Agricultural Engineering,2022,38(13):64−75

[34] 张凯,李晓楠,暴凯凯,等. 西北干旱露天煤矿排土场土壤重构与水盐运移机制[J]. 煤炭学报,2024,49(3):1556−1569

ZHANG Kai,LI Xiaonan,BAO Kaikai,et al. Soil reconstruction and water–salt transport mechanism of waste dump in arid open–pit coal mine in northwest China[J]. Journal of China Coal Society,2024,49(3):1556−1569

[35] LI Ronghui,CHEN Nengcheng,ZHANG Xiang,et al. Quantitative analysis of agricultural drought propagation process in the Yangtze River Basin by using cross wavelet analysis and spatial autocorrelation[J]. Agricultural and Forest Meteorology,2020,280:107809.

[36] ROBERTS C P,UDEN D R,CADY S M,et al. Tracking spatial regimes as an early warning for a species of conservation concern[J]. Ecological Applications,2022,32(1):e02480.

[37] 佘冬立,韩笑,孙枭沁,等. 基于CT扫描的滨海土壤孔隙空间网络表征与渗流模拟[J]. 农业机械学报,2023,54(5):308−315

SHE Dongli,HAN Xiao,SUN Xiaoqin,et al. Coastal soil pore space network characterization and seepage simulation based on CT scanning[J]. Transactions of the Chinese Society for Agricultural Machinery,2023,54(5):308−315

[38] 刘向君,朱洪林,梁利喜. 基于微CT技术的砂岩数字岩石物理实验[J]. 地球物理学报,2014,57(4):1133−1140

LIU Xiangjun,ZHU Honglin,LIANG Lixi. Digital rock physics of sandstone based on micro–CT technology[J]. Chinese Journal of Geophysics,2014,57(4):1133−1140

[39] ZHANG Zhihong,SU Ziyi,SONG Zhaoyang. Study on microstructure and permeability of a red clay area subjected to dry–wet cycles using X–ray micro computed tomography and AVIZO[J]. Journal of Hydrology,2025,656:133027.

[40] NI Xiaoming,MIAO Jie,LYU Runsheng,et al. Quantitative 3D spatial characterization and flow simulation of coal macropores based on μCT technology[J]. Fuel,2017,200:199−207.

[41] ZHAO Jianlin,QIN Feifei,DEROME D,et al. Improved pore network models to simulate single–phase flow in porous media by coupling with lattice Boltzmann method[J]. Advances in Water Resources,2020,145:103738.

[42] HIRD R,BOLTON M D. Clarification of capillary rise in dry sand[J]. Engineering Geology,2017,230:77−83.

[43] 秦程朝,陈育民,陈润泽,等. 砂土孔隙结构对注气减饱和过程气体运移的影响研究[J]. 岩土工程学报,2025,47(12):2468−2477

QIN Chengzhao,CHEN Yumin,CHEN Runze,et al. Study on influence of sand pore structure on air migration during air injected desaturation process[J]. Chinese Journal of Geotechnical Engineering,2025,47(12):2468−2477

[44] 马蒙蒙,林青,徐绍辉. 不同因素影响下层状土壤水分入渗特征及水力学参数估计[J]. 土壤学报,2020,57(2):347−358

MA Mengmeng,LIN Qing,XU Shaohui. Water infiltration characteristics of layered soil under influences of different factors and estimation of hydraulic parameters[J]. Acta Pedologica Sinica,2020,57(2):347−358

[45] SI Bing,DYCK M,PARKIN G W. Flow and transport in layered soils preface[J]. Canadian Journal of Soil Science,2011,91(2):127−132.

[46] 喻昭晟,陈晓斌,周雨晴,等. 红层软岩崩解面释放率与崩解特性研究[J]. 岩土力学,2025,46(增刊1):285−296

YU Zhaosheng,CHEN Xiaobin,ZHOU Yuqing,et al. Release rate of disintegration surface and disintegration characteristics of red–layer soft rock[J]. Rock and Soil Mechanics,2025,46(Sup.1):285−296

[47] 郭拿拿,黄明斌. 不同类型重构土壤水分运移特征[J]. 农业工程学报,2024,40(3):94−102

GUO Nana,HUANG Mingbin. Water movement characteristics of different reconstructed soils[J]. Transactions of the Chinese Society of Agricultural Engineering,2024,40(3):94−102

[48] 王强民,赵明,彭鸿杰,等. 旱区不同层状结构土壤的水分运移过程与模拟[J]. 水文地质工程地质,2023,50(4):84−94

WANG Qiangmin,ZHAO Ming,PENG Hongjie,et al. Water transport process and simulation of layered soils with different configurations in an arid region[J]. Hydrogeology and Engineering Geology,2023,50(4):84−94

[49] 吴奇凡,樊军,杨晓莉,等. 晋陕蒙接壤区露天矿层状土壤水分入渗特征与模拟[J]. 土壤学报,2015,52(6):1280−1290

WU Qifan,FAN Jun,YANG Xiaoli,et al. Experiment and simulation of infiltration from layered soils in open pit mine in Jin–Shaan–Meng adjacent region[J]. Acta Pedologica Sinica,2015,52(6):1280−1290