双圆盾构隧道杯型冻结壁温度场数值优化分析.

In order to obtain the variation law of temperature field at the starting end of double-circle shield tunnel reinforced by horizontal cup freezing method, combined with a double-circle shield tunnel section project of Shanghai Rail Transit Line 6, this paper established a numerical model by using finite element numerical simulation software, analyzed the development law of temperature field of cup-shaped frozen wall at the end of double-circle shield tunnel when the initial model designed with 102 frozen pipes. Two optimization schemes were put forward: scheme 1 was reducing the number of freezing pipes in inside, center and outside circles by 2, 4 and 6 respectively; scheme 2 was reducing the number of freezing pipes in inside, center and outside circles by 4, 6 and 10 respectively. The freezing effects of the initial model and two optimization schemes were analyzed and compared. The results showed that: at the beginning of freezing, the frozen soil curtain gradually extended outward around each freezing pipe in a cylindrical shape, and the closer it was to the freezing pipe, the better the freezing effect. The frozen soil curtain began to cross in the order of outer circle, center circle and inside circle, and formed an approximate double-round cup-shaped frozen wall with regular shape and uniform strength distribution on the 18 th day of freezing. The length of double round cup-shaped frozen wall cup bottom was 10.2 m, the height of cup body was 4.4 m, the thickness of cup wall was 2 m, and the thickness of cup bottom was 2 m.The initial freezing scheme which using 102 freezing pipes met the construction requirements, the freezing effect was good, and it was feasible in actual construction, but it was conservative. The two optimization schemes still met the starting cup-shaped freezing wall cup of shield machine requirements after reducing the number of freezing pipes. [ABSTRACT FROM AUTHOR]