Study on Impact of Various Void Conditions on Shallow Rectangular Masonry-Concrete Power Tunnel and Surrounding Roads

Table 1

Electrical property parameters of common media.

Medium types	Relative dielectric constant	Electromagnetic wave velocity (m/ns)
Air	1	0.3
Concrete	4∼10	0.095∼0.150
Brick wall	5–20	0.057∼0.134
Soil layer	3∼40	0.047∼0.173