20年来,两淮地区负责施工的冻结井筒有70多个,其中7个冻结深度超过300米(表1)。在打钻、冻结、凿砌施工和理论 研究方面都取得了一些经验。但因对深井冻结理论的研究和对冻土的物理机械性能的了解还不够深入,致使近几年在施工较深的冻 Over the past 20 years, there have been over 70 frozen boreholes in the Huaihe area, of which 7 have frozen more than 300 meters (Table 1). Some experience has been gained in drilling, freezing, chipping construction and theoretical research. However, due to the deep freezing theory and understanding of the physical and mechanical properties of frozen soil is not yet deep enough, resulting in the construction of the recent years, deep frozen