ABSTRACT
Most of underground structures are built in grounds where without some means of improvement can not maintain their stability. These reinforcement operations range widely from compaction, drainage and grouting of soft soils to installation of fully grouted bolts and applying shotcrete in jointed and blocky rock masses. The amount of ground improvement measures which is really adequate for each job is a challenging question in front of the engineers. A heavy reinforcing system can assure safety but is often not economical. On the other hand, insufficient measures will not assure the safety of the structures therefore having an accurate ground improvement program always is a question to be answered.
