Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment
Fractured rock mass is extensively distributed in Karst topography regions, and its geological environment is different from that of the quaternary strata. In this study, the influences on geological environment induced by the construction and operation of a large-scale borehole group of ground sour...
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MDPI AG
2024-03-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/17/6/1384 |
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| author | Yujin Ran Jia Peng Xiaolin Tian Dengyun Luo Bin Yang Peng Pei Long Tang |
| author_facet | Yujin Ran Jia Peng Xiaolin Tian Dengyun Luo Bin Yang Peng Pei Long Tang |
| author_sort | Yujin Ran |
| collection | DOAJ |
| description | Fractured rock mass is extensively distributed in Karst topography regions, and its geological environment is different from that of the quaternary strata. In this study, the influences on geological environment induced by the construction and operation of a large-scale borehole group of ground source heat pumps are analyzed by a thermo-hydro-mechanical (THM) coupling numerical model. It was found that groundwater is redirected as the boreholes can function as channels to the surface, and the flow velocity in the upstream of borehole group is higher than those downstream. This change in groundwater flow enhances heat transfer in the upstream boreholes but may disturb the original groundwater system and impact the local geological environment. Heat accumulation is more likely to occur downstream. The geo-stress concentration appears in the borehole area, mainly due to exaction and increasing with the depth. On the fracture plane, tensile stress and maximum shear stress simultaneously occur on the upstream of boreholes, inducing the possibility of fracturing or the expansion of existing fractures. There is a slight uplift displacement on the surface after the construction of boreholes. The correlations of the above THM phenomena are discussed and analyzed. From the modeling results, it is suggested that the consolidation of backfills can minimize the environmental disturbances in terms of groundwater redirection, thermal accumulation, occurrence of tensile stress, and possible fracturing. This study provides support for the assessment of impacts on geological environments resulting from shallow geothermal development and layout optimization of ground heat exchangers in engineering practices. |
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| format | Article |
| id | doaj.art-57246c62eed04e23acadcf77716abf12 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-24T18:21:13Z |
| publishDate | 2024-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-57246c62eed04e23acadcf77716abf122024-03-27T13:35:36ZengMDPI AGEnergies1996-10732024-03-01176138410.3390/en17061384Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological EnvironmentYujin Ran0Jia Peng1Xiaolin Tian2Dengyun Luo3Bin Yang4Peng Pei5Long Tang6Guizhou Shallow Geothermal Energy Development Co., Ltd., Zunyi 563006, ChinaGuizhou Shallow Geothermal Energy Development Co., Ltd., Zunyi 563006, ChinaGuizhou Shallow Geothermal Energy Development Co., Ltd., Zunyi 563006, ChinaGuizhou Shallow Geothermal Energy Development Co., Ltd., Zunyi 563006, ChinaCollege of Mines, Guizhou University, North Wing Rm. 426, Guiyang 550025, ChinaCollege of Mines, Guizhou University, North Wing Rm. 426, Guiyang 550025, ChinaSchool of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaFractured rock mass is extensively distributed in Karst topography regions, and its geological environment is different from that of the quaternary strata. In this study, the influences on geological environment induced by the construction and operation of a large-scale borehole group of ground source heat pumps are analyzed by a thermo-hydro-mechanical (THM) coupling numerical model. It was found that groundwater is redirected as the boreholes can function as channels to the surface, and the flow velocity in the upstream of borehole group is higher than those downstream. This change in groundwater flow enhances heat transfer in the upstream boreholes but may disturb the original groundwater system and impact the local geological environment. Heat accumulation is more likely to occur downstream. The geo-stress concentration appears in the borehole area, mainly due to exaction and increasing with the depth. On the fracture plane, tensile stress and maximum shear stress simultaneously occur on the upstream of boreholes, inducing the possibility of fracturing or the expansion of existing fractures. There is a slight uplift displacement on the surface after the construction of boreholes. The correlations of the above THM phenomena are discussed and analyzed. From the modeling results, it is suggested that the consolidation of backfills can minimize the environmental disturbances in terms of groundwater redirection, thermal accumulation, occurrence of tensile stress, and possible fracturing. This study provides support for the assessment of impacts on geological environments resulting from shallow geothermal development and layout optimization of ground heat exchangers in engineering practices.https://www.mdpi.com/1996-1073/17/6/1384borehole groupkarst fracturethermo-hydro-mechanical couplingnumerical simulationgeological environment |
| spellingShingle | Yujin Ran Jia Peng Xiaolin Tian Dengyun Luo Bin Yang Peng Pei Long Tang Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment Energies borehole group karst fracture thermo-hydro-mechanical coupling numerical simulation geological environment |
| title | Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment |
| title_full | Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment |
| title_fullStr | Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment |
| title_full_unstemmed | Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment |
| title_short | Numerical Study of the Thermo-Hydro-Mechanical Coupling Impacts of Shallow Geothermal Borehole Groups in Fractured Rock Mass on Geological Environment |
| title_sort | numerical study of the thermo hydro mechanical coupling impacts of shallow geothermal borehole groups in fractured rock mass on geological environment |
| topic | borehole group karst fracture thermo-hydro-mechanical coupling numerical simulation geological environment |
| url | https://www.mdpi.com/1996-1073/17/6/1384 |
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