circular tunnel
2.Abstract: The formulas of EM wave attenuation rate and the mode equations in an empty circular tunnel are given, and they are solved through numerical analysis method, and the main conclusions we obtain are as follows:when the conductivity of tunnel is high, the attenuation rate obtained from conventional metal wave guide approximation is correct; if frequency is higher, the attenuation rate is smaller; it is beneficial for EM waves to propagate when tunnel radius is larger; for TE modes, the changes of dielectric constant and magnetic permeability of tunnel have little effect on that of the attenuation rate; for TM modes, the dielectric constant or magnetic permeability of tunnel is bigger, the attenuation rate is higher.
3.The wave function expansion method is used to analyze the interaction of blasting seismic wave and the adjacent chambers, the influences of such factors as the radius of tunnel, the frequency of incident blasting seismic wave, rock mass types etc, on dynamic response and safe peak partical velocity (PPV)of circular tunnel are discussed.
4.The creep of adjoining rock of a circular section tunnel and frozen wall in underground engineering is simulated by the method of photoviscoelasticity. The regularities of the stress distribution and its variations with time are given out. An effective experimental means is provided for design and forecast of underground engineering.
