ABSTRACT
The natural obstacles encountered in areas where the karst surface is overlain with clay constitute special hazards in construction. These include a widely varying strike of the rock surface, rocks and boulders near the firm rock, sinkholes, and zones of soft, wet and poor soil in perched water zones. Often standard construction approaches do not work. Even with good pre-construction geotechnical investigation, surprises are normal. A number of projects are described which illustrate both unexpected problems and how construction choices were made. Some new variations and combinations of construction techniques are described.
