Research on In Situ Stress Distribution of the Railway Tunnels in Southwest China Based on the Complete Temperature Compensation Technology

Table 6

The calculation equation of φ.

Quadrant of principal stress	I	II	III	IV	V	VI	VII	VIII
Coordinate axis	(+, +, +)	(−, +, +)	(−, −, +)	(+, −, +)	(+, +, −)	(−, +, −)	(−, −, −)	(+, −, −)
(l, m, n)	(+, +, +)	(−, +, +)	(−, −, +)	(+, −, +)	(+, +, −)	(−, +, −)	(−, −, −)	(+, −, −)
φ