Experimental Investigations on Repair and Permeability Reduction for Single Sandstone Fracture Using a Mixed CaCO<sub>3</sub> and Fe(OH)<sub>3</sub> Precipitate
In China, groundwater loss caused by underground coal mining is becoming increasingly serious. The key to groundwater restoration is to repair mining-induced water-conducting fractures (WCFs) in the overlying strata. In this study, the adsorption–consolidation sealing characteristics of chemical pre...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
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| Series: | Applied Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-3417/14/22/10617 |
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| Summary: | In China, groundwater loss caused by underground coal mining is becoming increasingly serious. The key to groundwater restoration is to repair mining-induced water-conducting fractures (WCFs) in the overlying strata. In this study, the adsorption–consolidation sealing characteristics of chemical precipitates were used to conduct permeability reduction (PR) experiments, including adding mixed CaCO<sub>3</sub> and Fe(OH)<sub>3</sub> to a sandstone specimen with a single fracture at room temperature. An aqueous solution of Na<sub>2</sub>CO<sub>3</sub> was used as the simulated groundwater, and a solution of mixed CaCl<sub>2</sub> and FeCl<sub>2</sub> was used as the repair reagent to simulate the water seepage conditions of a fractured rock mass. The two aqueous solutions were simultaneously injected into a single-fractured rock specimen at a constant flow rate. The experimental results show that the Fe(OH)<sub>3</sub> colloid encapsulated CaCO<sub>3</sub> crystals in a mixed precipitate, reducing the overall structural stability of the mixed precipitate and restricting repair and PR efficiency. However, the Fe(OH)<sub>3</sub> precipitate had better PR efficiency in the initial stage of the experiment. Therefore, a better scheme was put forward to repair the WCF, utilizing a mixed Fe(OH)<sub>3</sub> and CaCO<sub>3</sub> precipitate with a molar ratio close to 1:4 in the early stage and a single CaCO<sub>3</sub> precipitate in the later stage. |
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| ISSN: | 2076-3417 |