EXPERIMENTAL RESEARCH FOR THE LINERS OF THE SWISSMETRO TUNNELS
Swissmetro is an innovative concept for a very high-speed underground passenger transportation system. One of its features is that the small diameter tunnels are under permanent partial vacuum. This paper presents the results of an experimental research program conducted on the behavior of concrete liners subjected to service conditions of Swissmetro tunnels. In one series of tests air flow was measured through cracked concrete subjected to a differential of air pressure. In a second series of tests, concrete elements were subjected to a large number of cycles of pressure variations under partial vacuum conditions to investigate possible degradation of the concrete surface properties.
Swissmetro - Tests on Air Permeability of Concrete
Air-tightness of the concrete lining is a critical factor for a railway tunnel to be operated under partial vacuum. The testing described in this article investigates the influence on air permeability of aggregate composition (sand content, maximum grain size), type of cement, addition of steel fibers, degree of saturation of the concrete, and use of a curing compound. Laboratory testing was performed on samples taken from 18 concrete wall elements representing a range of pumped concrete mixtures. Fresh-concrete properties, compressive strength, and porosity were also measured. This report handles the first 12 concrete mixtures. Evaluation of the remaining testing is still in progress.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).