Application of seismic refraction techniques in engineering practice with special emphasis on pavement systems.

摘要

Seismic techniques in general Civil Engineering practice are tools to obtain elastic constants of engineering materials at low strain values. In geotechnical engineering, the seismic refraction technique determines the thickness and moduli of different soil layers. In this study, the application of the technique is presented. The research extended the existing methods to obtain soil parameters and the variation of moduli with depth for soil formations exhibiting gradual increase of wave velocity with depth.; In pavement applications, measuring compression wave velocity provides a simple and low cost measure of soil properties. Body wave velocity measurements of flexible pavements are usually restricted to the asphalt concrete layer. The variables affecting the propagation velocity of the seismic waves were studied. Also, the study included the assessment of the variation of the elastic moduli of asphalt concrete with temperature.; Wave-propagation methods are used to measure the velocities of elastic waves traveling through the pavement system rather than the deflection caused by an energy source. One objective of this study was to develop seismic wave velocity measurements as a supplement to deflection basin measurements using the falling weight deflectometers (FWD) in order to improve estimates of the moduli of the asphalt concrete surface.; For new pavement construction, the study has been aimed at developing techniques for obtaining moduli for the different pavement layers at reasonable cost and at controlling compaction during construction. The seismic velocity technique also has potential uses in monitoring the pavement condition, as an indicator of needed maintenance such as overlay.