| Popis: |
Papua New Guinea (PNG) is host to several topographically, geologically and climatically different environments. The central and western provinces of the mainland (‘the highlands’) are topographically elevated between 1,000 and 4,000 m above sea level. The terrain is very rugged and the climate is cool all year round. This region is hosted by uplifted sea floor sedimentary rocks, some of which have been metamorphosed. There is no wet or monsoon season. Rather, rainfall occurs quite steadily all year round. Annual rainfall can easily exceed 10,000 mm in some areas and low magnitude earthquakes are frequently experienced. The smaller outer islands are topographically flatter, seismically active and receive in the order of 5,000 mm annual rainfall. Rainfall usually occurs in the form of high intensity thunderstorms. The climate is very hot and humid. These islands often comprise a combination of volcanics and some sedimentary rocks. Mining is a major industry in PNG and very large open pits have been constructed with excavated slope heights ranging from 300 to 1,000 m. Open pit mine slopes are designed with a serviceable life of no more than 10 to 20 years. As such, predicted and well-managed failures or landslides are usually considered acceptable. Waste rock and low-grade ore are often placed in constructed rockfill dumps and stockpiles which range in heights from 50 to over 300 m. High rockfill slope heights developed on often steep foundations, coupled with the erosive and pore pressure effects of rainfall and seismicity can create significant landslide hazards. This paper presents the cumulative efforts of practitioners managing risks associated with rockfill dumps and stockpiles in PNG. |
