External thermal resistance of the surrounding soil of a tunnel.

In order to use the deep tunnel thermal inertial correction, the outer diameter is calculated for rectangular tunnel and the formula for circular shape is used.

Symbol
$T_{\mathrm{e}}$
Unit
K.m/W
Formulae
 $T_{\mathrm{tw}} + \frac{\rho_{\mathrm{4}}}{2 \pi} \ln{\left (u + \sqrt{u^{2} - 1} \right )}$ circular shape and rectangular shape acc. JCS Standard $T_{\mathrm{tw}} + \frac{\rho_{\mathrm{4}}}{2 \pi} \ln{\left (\frac{3.388 L_{\mathrm{cm}}}{\sqrt{A_{\mathrm{t}}}} \right )}$ rectangular shape acc. IEC Standard
Related
$A_{\mathrm{t}}$
$L_{\mathrm{cm}}$
$\pi$
$\rho_{\mathrm{4}}$
$T_{\mathrm{tw}}$
$u$
Used in
$\Delta \theta_{\mathrm{0t}}$
$L_{\mathrm{0}}$
$T_{\mathrm{4t}}$
$\theta_{\mathrm{at_{\mathrm{L}}}}$
$\theta_{\mathrm{at_{\mathrm{z}}}}$
$\theta_{\mathrm{to}}$
$\theta_{\mathrm{to_{\mathrm{z}}}}$
$W_{\mathrm{a_{\mathrm{L}}}}$
$W_{\mathrm{a_{\mathrm{z}}}}$