(GRS 230) Investigations on Self-Sealing of Indurated Clay

Chun-Liang Zhang, Tilmann Rothfuchs, Jürgen Dittrich, Jürgen Müller

Within the framework of the integrated NF-PRO project, initiation, development, and self-sealing / healing of the excavation damaged zone (EDZ) around a repository in indurated clay were investigated, including laboratory tests, field observations, and numerical modelling. GRS contributed with a comprehensive laboratory programme to WP4.3 (EDZ short term evolution) examining ventilation effects on deformation and damage of the Opalinus clay and to WP4.4 (EDZ long term evolution) providing evidence for self-sealing of both the Opalinus clay and the Callovo-Oxfordian-argillite. Within WP4.4, various self-sealing experiments were carried out on strongly damaged clay samples by measuring the gas permeability as a function of the confining stress before and after water resaturation. All laboratory observations suggest a high selfsealing capacity of the studied clay rocks. In addition, modelling exercises were also performed. Details of the work are given in this report.