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针对当前多圈孔冻结造成的冷量分配不合理以及大圈径冻结孔布置与永久井架基础的矛盾,运用现场实验与数值模拟对比分析冻结器套管抽真空保温与聚氨酯保温的优劣性.实验表明:在目前技术水平下套管抽真空真空度不够导致隔温效果差、持续时间短;采用聚氨酯保温冻结器,管外土体降温梯度小于未保温情况,且与未保温冻结器管外温差随冻结期增长趋于稳定.在目前施工技术水平下,用聚氨酯对冻结器进行保温是非常有效的.
In view of the unreasonable cooling capacity distribution caused by multi-hoop freezing and the contradiction between the layout of large-diameter freezing holes and the foundation of permanent derrick, the advantages and disadvantages of vacuum-insulated and polyurethane insulation of freezer bushing were compared and analyzed by field experiments and numerical simulation. The experimental results show that under the current technical level, the vacuum degree of casing vacuum is not enough, which results in poor insulation effect and short duration. The cooling gradient of soil outside the tube is less than that of non-insulated tube with polyurethane insulation and freezer, The temperature increase tends to be stable with the freezing period.Under the current construction technology level, it is very effective to heat the freezer with polyurethane.