ABSTRACT
Earthquakes have caused some damage to abandoned quarries in Oya region, Japan and the behaviour of pillars of Oya tuff quarries is therefore of paramount importance for the region. This study reports investigation results of Oya tuff pillars under static and dynamic conditions. Also, the backfilling of underground quarries is considered as a countermeasure of collapse in the long term and during earthquakes. For this purpose, an experimental laboratory program was initiated to investigate the static and dynamic response of Oya tuff pillars. The shock tests demonstrate that the overall stiffness of samples subjected to shock loading is higher than that of samples under static loading. With respect to backfilling, the results show that, the overall stiffness of backfilled samples is higher than that of unfilled and in some cases, the yielding strength of backfilled samples displays strain hardening behaviour, while unfilled samples show strain softening behaviour. Different degrees of backfilling, indicate that partial backfilling is not effective to prevent ground settlement.
