Abstract:

Determining the freezing pipe spacing, the freezing reinforcement scope and freezing reinforcement techniques, and acquiring the development and distribution patterns of the temperature field of the frozen soil walls are key issues that need to be addressed when the soil of shield launching shafts is reinforced by vertical freezing method. In the paper, the influence of different freezing pipe spacing on the development of the temperature field of the vertical frozen wall is studied by means of finite element analysis software and on basis of the shield launching project of the crossriver shield tunnel on Line 10 of Nanjing Metro. The numerical simulation shows that: 1) It is feasible to simulate the temperature field of the vertical frozen wall by means of the numerical model established; 2) Decreasing the freezing pipe spacing has obvious influence on the temperature field; Every time when the freezing pipe spacing increases 0.1m, the crosslap time of the frozen wall increases about 1 day; 3) With the increasing of the freezing pipe spacing, the crosslap time of the frozen wall increases linearly; 4) The smaller the freezing pipe spacing, the lower the temperature of the frozen wall, and the more uniform the strength of the frozen wall. 

Key words: shield launching, vertical frozen wall, freezing pipe spacing, temperature field, numerical simulation