Abstract: To solve the technical problems encountered in the construction of new underground passage projects close to the existing structure in the development of underground space，based on the underground tunnel project of Old Hongzhen Street in Shanghai, the authors expound an innovative application practice of freezing method. This method combines freezing mining method with open-cut method and local reverse building method, and can be applied to the new underpass project close to the existing structure. The design scheme, freezing scheme, implementation process，implementation effect, and monitoring data are analyzed. The following conclusions are drawn: (1) The combination of freezing mining method and opencut method is workable and has been approved by practical engineering. (2) The construction monitoring data show that during the construction of the new underground passage, the structural deformation of the existing metro entrance No.1 is within the controllable range. The technology can achieve the purpose that the existing metro passage is not stopped and the new passage has low impact on the existing subway structure. (3) The measures of intermittent freezing and opening pressure relief holes can effectively control the adverse effects of frost heaving, and the vertical deformation of the existing structure caused by frost heaving can be reduced by 40% to 75% within 7 days after taking the measures.

Key words: freezing method, mining method, open-cut method, underground passage, subway entrance, deformation control