Advances in Materials Science and Engineering · 2020 · 20 citations · 2 references
EngineeringCivil EngineeringGeotechnical EngineeringHydrogeologySoil MechanicsFrozen Ground ProcessesGround FreezingUnderground Excavation MethodsArtificial Ground FreezingExcavationFreezingNumerical Modeling Of Ground FreezingSeepageSoil Structure Changes During FreezingTemperature Field AnalysisUnderground Construction
In Beijing’s water‑rich sandy gravel strata, artificial ground freezing is investigated for large‑scale underground projects, revealing how multi‑row freezing pipes interact and produce a group effect during the freezing process. The study proposes the basin‑shaped freezing method (BFM) as an AGF application for underground engineering. BFM consists of a frozen curtain forming the basin wall and a horizontal frozen body forming the basin bottom, and its temperature field expansion was examined through physical model tests and numerical simulations under two conditions. The results show that the group effect expands the freezing area, progressing from back to front water surfaces under seepage, and that BFM effectively waterproofs the excavation by forming sufficient frozen thickness in both the basin wall and bottom.
Based on typical water‐rich sandy gravel strata in Beijing, in order to explore the application of the artificial ground freezing method (AGF) in urban large‐scale underground engineering, the formation and development of freezing body were analyzed when multirow freezing pipes were working together, and the group effect exhibited during the freezing process was also revealed in this paper. On this basis, the basin‐shaped freezing method (BFM) is put forward as an application of AGF used in underground engineering. BFM structure consists of two parts: the frozen curtain (basin wall) around the excavation scope and the horizontal frozen body (basin bottom) at the bottom of the station. Physical model test and numerical simulation were conducted to study temperature field expansion of BFM under two different conditions. The results show the following: (1) The group effect refers to the cooling effect of different freezing pipes influencing each other during freezing process. Under the condition of still water, the group effect expands the freezing area, and it shows the gradual development of freezing from back water surface to front water surface under seepage condition. (2) BFM can effectively play the role of water proofing, and although different parts of basin structure show different frozen order under different conditions, both basin wall and basin bottom can form an effective thickness during the freezing process.
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