Finite Element Analysis of Natural Thawing Heat Transfer of Artificial Frozen Soil in Shield-Driven Tunnelling

Table 4

Temperature gradient inwardly and outwardly from freeze pipe with different thawing times.

Thawing time (day)	Temperature gradient outwardly (°C/m)	Temperature gradient inwardly (°C/m)
0	28.0	14.9
2	8.8	7.0
4	3.1	0.6
10	4.6	9.7
20	4.3	9.6
30	2.5	7.4
40	−3.1	1.7
50	−3.4	0.1
80	−0.6	−1.1
120	−0.1	−1.2