关键词: 立井井筒, 冻结法, 井壁结构, 理论计算

Abstract: In order to ensure the safety and efficiency of the freezing method construction of the main shaft of Fang′an Gold Mine，based on the engineering and hydrogeological conditions of the location of the main shaft of Fang′an Gold Mine，and in combination with the construction experience parameters of the freezing method for the shaft wall in the surrounding mines，the freezing method was adopted for the construc⁃ tion of the fourth system and the weathering layer area of the shaft of Fang′an Gold Mine. The composite sandwich wellbore wall support form is adopted to determine the freezing depth，the thickness of the inner and outer wellbore wall supports and the reinforcement parameters，the height of the wall base and other wellbore construction technical parameters. A 50 mm thick polystyrene foam plastic board is laid between the outer wall and the frozen wall，and a 1.5 mm thick polyethylene plastic thin plate is laid between the in⁃ ner and outer walls. This enables the inner wall to freely expand and contract during the solidification pro⁃ cess，reduces the gaps caused by temperature differences between the inner and outer walls during the dry shrinkage of concrete. After the wall base construction，a sliding formwork is applied to the inner wall. Before the frozen soil thaws，post-wall grouting and water blocking measures are taken for the wellbore. For the in⁃ ner and outer walls above the wall base，inter-wall grouting measures are adopted to fill the wellbore cracks and block the water gushing. During the construction process，the outer wall concrete support of the frozen section of the well shaft was monitored to ensure that the thickness of the concrete was not less than the de⁃ signed thickness，it was vibrated tightly，the concrete mix ratio was automatically measured by computer，the appearance was smooth and flat，there were no cracks when inspected from top to bottom，and the concrete joints were tight. Through theoretical calculation，the rationality of the wellbore structure parameters in the freezing section is verified to ensure the freezing and construction safety of the wellbore，providing reference for the freezing method well drilling design in the Huai River region.

Key words: shaft wellbore, freezing method, shaft wall structure, theoretical calculation