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 - AIR PERMEABILITY OF CRACKED CONCRETE PLATES
The object of this paper is the prediction of the air flow through a cracked concrete wall element. Experimental data from permeability tests on large cracked reinforced concrete plates is used. The variation of the flow with the crack opening is investigated. A new empirical expression is developed for the calculation of the friction coefficient for the flow of air through a concrete crack. It is based on the general formulation of a turbulent or laminar flow of a gas between two parallel surfaces. It is a function of the crack width and of the maximum aggregate size of the concrete aggregate. Background Several studies have been conducted in the past 30 years to investigate air and water flow through cracked concrete (E.g. [Buss 72] and [Mivellaz 96]). Much of this research work was conducted in North America and Japan on behalf of the nuclear industry. It is clear form the review of the literature that there are still disagreements on the topic of the calculation of the air flow rate through cracked concrete [Fellay and Badoux 2001]. This paper focuses on the use of new experimental data to develop an expression for the friction coefficient for air flow through a crack in a reinforced concrete plate. The research presented below was conducted in the context of a research program on the Swissmetro transportation system. Swissmetro is an innovative concept for a very high-speed underground passenger Maglev type transportation system. One of its features is that the tunnels are under permanent partial vacuum, thus requiring “air proof” tunnel liners. The first objective of the research project was the experimental investigation of the “air tightness” of reinforced concrete elements. Experimental program An experimental testing program in two phases was conducted to compare and quantify the air permeability of reinforced concrete elements which could be used for Swissmetro tunnel liners. The objective of the first phase was to assess the influence of the concrete mix design on the permeability to gas of uncracked concrete samples. The permeability of eighteen concrete mixes was tested for different humidity levels and under different pressure differentials.
Perturbed angular correlation study of a haptenic molecule.
The angular correlation of the 173-247 keV gamma-ray cascade after the electron-capture decay of (111)In is strongly perturbed when the 1-p-nitrophenyl-ethylenediaminetetraacetate chelate of (111)In(8+) is added to a solution containing rabbit antibody to dinitrophenyl groups. The radioactive chelate can be displaced by the addition of dinitrophenyllysine or unlabeled chelate. The average association constant between the antibody and the labeled chelate has been estimated from perturbed angular correlation measurements; this value is compared to the results of equilibrium dialysis. These experiments provide good evidence that information concerning macromolecular behavior can be obtained from perturbed angular correlation experiments that use chemically specific labels.