岩盤を対象とした原位置トレーサ試験の現状

Abstract

This report explains the present state of in-situ tracer experiment techniques for rock mass and the points to remember when conducting in-situ tests.There are several methods for in-situ tracer experiment. First their principles, advantages and disadvantages and application examples to rock mass are described for typical in-situ tracer testing methods. Point dilution test and single-well injection-withdrawal test are introduced as typical single-hole tracer testing methods. On the other hand, natural gradient test, radially divergent test, radially converging test and dipole test are introduced as typical cross-hole tracer testing methods.A tracer injection system and a recovery system are required to conduct an in-situ tracer experiment. Secondly equipments for in-situ tracer experiment are outlined with testing procedure. And points to remember for test equipments are described.Selection of tracers is one of the most important issues for a successful in-situ tracer experiment. Conservative tracers are used to investigate the phenomena of advection and dispersion, whereas reactive tracers are used to address the phenomena of sorption and matrix diffusion. Thirdly desirable conditions for conservative tracers and generally used conservative tracers are described. And the points to remember for selecting reactive tracers and concentration of injected tracers are outlined.In order to conduct an in-situ tracer experiment successfully and estimate the characteristics of rock mass for solute transport accurately, geological and hydraulical characteristics of rock mass should be investigated closely prior to the in-situ tracer experiment. Finally the procedure for investigating the transport properties of rock mass is outlined including prior geological and hydrological surveys as well as in-situ tracer experiments.