首页|CaCO3/Fe(OH)3修复单一裂隙岩样的降渗试验

CaCO3/Fe(OH)3修复单一裂隙岩样的降渗试验

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采煤引起的覆岩导水裂隙广泛发育是导致地下水流失与生态损伤的重要原因,科学实施导水裂隙的修复降渗对于实现采损含水层生态功能修复与煤矿绿色开采意义重大.利用化学沉淀易发生吸附-固结而形成封堵降渗作用的特性,开展了 CaCO3/Fe(OH)3修复单一裂隙岩样的降渗试验.以Na2CO3水溶液作为模拟地下水,CaCl2水溶液和FeSO4水溶液分别作为修复试剂,模拟裂隙岩体的导水渗流条件,将模拟地下水和修复试剂以恒流方式同时注入单一裂隙岩样中,最终得到了两种沉淀物分别对两个不同裂隙发育岩样的修复降渗规律.试验结果表明,两种沉淀物对岩样裂隙均起到明显降渗作用,但由于两者微观结构及固结成垢机制的差异,造成对裂隙修复降渗效果的不同.CaCO3沉淀属典型晶态沉淀,依靠晶种吸附和晶体生长固结成核,形成的固结体结构紧密、稳定性好,对裂隙易产生良好的修复降渗效果;两个岩样分别历经400 min和208 min后的降渗幅度即达到220倍和175倍.而Fe(OH)3沉淀属典型非晶态沉淀,单纯依靠沉淀胶体的范德华力吸附于裂隙面并积聚固结,水温偏高易降低范德华力造成沉淀固结体结构疏松,难以抵抗高水压冲蚀作用,修复过程易出现降渗曲线频繁"反弹"现象;将试验水温由28 ℃降至8 ℃时,裂隙降渗幅度即由35倍提升至106倍,修复降渗效果显著提高.表明Fe(OH)3沉淀适宜用于浅部相对低温条件的裂隙岩体修复降渗,而CaCO3沉淀修复裂隙适宜的水温区间更广.研究结果可为化学沉淀修复导水裂隙的含水层生态功能修复实践提供参考.
Permeability reduction test of CaCO3/Fe(OH)3 repairing single fractured rock specimens
The extensive development of water-conducting fractures caused by coal mining in overly-ing strata is an important cause of groundwater loss and ecological damage,and the scientific implemen-tation of water-conducting fractures permeability reduction is of great significance for the realization of ecological function restoration of mining-damaged aquifers and green mining.Utilizing the characteristics that chemical precipitation is prone to adsorption-consolidation to form plugging,the permeability reduc-tion tests of repairing single fractured rock samples with CaCO3 and Fe(OH)3 were carried out.Using Na2CO3 aqueous solution as simulated groundwater,CaCl2 aqueous solution and FeSO4 aqueous solution as repair reagent respectively,and simulating the seepage condition of fractured rock mass,the simulated groundwater and repair reagent were simultaneously injected into a single fractured rock sample at a con-stant current.Finally,the repair and permeability reduction laws of two kinds of precipitates for two dif-ferent fractured rock samples were obtained.The test results showed that the two kinds of precipitates have obvious anti-seepage effect on rock fracture,but the effect of fracture repair was different due to the difference of micro-structure and scaling mechanism between them.CaCO3 precipitation was a typical crystalline precipitation,which was nucleated by crystal adsorption and growth consolidation with com-pact structure and good stability.It was easy to have a good effect on fracture repair and permeability re-duction.The permeability reduction ranges of two rock samples were 220 times and 175 times after 400 min and 208 min,respectively.However,the precipitation of Fe(OH)3 was a typical amorphous precip-itation,which depended solely on the van der Waals force of the precipitated colloid to adsorb on the fracture surface accumulated for consolidation.The high water temperature could easily reduce the van der Waals force and caused the structure of the precipitated consolidation body to be loose,so it was dif-ficult to resist the erosion effect of high water pressure,and the permeability reducing curve was easy to"rebound"frequently in the repair process.When the test temperature was reduced from 28 ℃ to 8 ℃,the extent of fracture permeability reduction was increased from 35 times to 106 times,and the effect of repairing and reducing permeability was significantly improved.This indicated that Fe(OH)3 precipitation is suitable for repairing in shallow fractured rock mass under relatively low temperature con-ditions,while CaCO3 precipitation had a wider range of water temperature.The research results provide reference for the practice of ecological function restoration of aquifers repaired by chemical precipitation.

repair water-conducted fracturechemical precipitationadsorption & consolidationper-meabilityecological remediation of mining-damaged aquifergreen mining

鞠金峰、李全生、许家林、李娟娟

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中国矿业大学矿山互联网应用技术国家地方联合工程实验室,江苏 徐州 221008

中国矿业大学物联网(感知矿山)研究中心,江苏 徐州 221008

煤炭开采水资源保护与利用全国重点实验室,北京 100011

国家能源投资集团有限责任公司,北京 100011

中国矿业大学煤炭精细勘探与智能开发全国重点实验室,江苏 徐州 221116

中国矿业大学深地工程智能建造与健康运维全国重点实验室,江苏 徐州 221116

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导水裂隙修复 化学沉淀 吸附-固结 渗透率 含水层生态功能修复 绿色开采

国家重点研发计划中央高校基本科研业务费专项国家自然科学基金

2021YFC29021042020ZDPYMS1951604259

2024

10.13545/j.cnki.jmse.2023.0476

采矿与安全工程学报
中国矿业大学 中国煤炭工业劳动保护科学技术学会

采矿与安全工程学报

CSTPCD北大核心
影响因子：2.054
ISSN：1673-3363
年,卷(期)：2024.41(1)
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