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2002

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Articles 3121 - 3128 of 3128

Full-Text Articles in Physical Sciences and Mathematics

Cave Breakdown By Vadose Weathering, R. A. L. Osborne Jan 2002

Cave Breakdown By Vadose Weathering, R. A. L. Osborne

International Journal of Speleology

Vadose weathering is a significant mechanism for initiating breakdown in caves. Vadose weathering of ore bodies, mineral veins, palaeokarst deposits, non-carbonate keystones and impure, altered or fractured bedrock, which is intersected by caves, will frequently result in breakdown. Breakdown is an active, ongoing process. Breakdown occurs throughout the vadose zone, and is not restricted to large diameter passages, or to cave ceilings. The surfaces of disarticulated blocks are commonly coated, rather than having fresh broken faces, and blocks continue to disintegrate after separating from the bedrock. Not only gypsum, but also hydromagnesite and aragonite are responsible for crystal wedging. It …

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Karst Breakdown Mechanisms From Observations In The Gypsum Caves Of The Western Ukraine: Implications For Subsidence Hazard Assessment, Alexander Klimchouk, Vjacheslav Andrejchuk Jan 2002

Karst Breakdown Mechanisms From Observations In The Gypsum Caves Of The Western Ukraine: Implications For Subsidence Hazard Assessment, Alexander Klimchouk, Vjacheslav Andrejchuk

International Journal of Speleology

The term karst breakdown is employed in this paper to denote the totality of processes and phenomena of gravitational and/or hydrodynamic destruction of the ceiling of a karst cavity and of the overlying sediments. It refers not only to the existence of a surface subsidence (collapse) feature but, first of all, to the “internal” (hidden in the subsurface) structures that precede development of a surface form. This study reports and discusses the results of direct mapping and examination of breakdown structures in the gypsum karst of the Western Ukraine, at the level of their origin, i.e. in caves. The accessibility …

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Collapse Dolines And Deflector Faults As Indicators Of Karst Flow Corridors, France Šušteršič Jan 2002

Collapse Dolines And Deflector Faults As Indicators Of Karst Flow Corridors, France Šušteršič

International Journal of Speleology

The paper concerns collapse dolines, which appear to be one of the best-defined surface karst phenomena. Despite this appearance, one may find quite different views in the literature, and some of the aspects of their morphogenesis have been overlooked completely. Among these aspects the most obvious is the question of the ongoing development of the closed depression. Five of the most common collapse doline types found in Slovenia are considered in terms of general systems theory, leading to a conclusion that cave roof collapse remains the crucial event in a collapse doline’s development. However, the collapse event itself may be …

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Stability Appraisal Of The Medvedova Konta Pothole, Jože Kortnik Jan 2002

Stability Appraisal Of The Medvedova Konta Pothole, Jože Kortnik

International Journal of Speleology

Until 1956 the underground details of areas around Pokljuka were practically unknown due to the area’s non-karstic outward appearance. However, the presence of karst phenomena on this Alpine plain is undoubtedly indicated, primarily by the absence of a surface drainage network. A mathematical model was made of the Medvedova konta pothole, in which two different sets of material properties were used, corresponding to the Triassic limestone that forms the bedrock under the greater part of Pokljuka. The model simulates the gradual thinning of the ceiling of the underground hall, from the surface downwards, until its collapse. The paper presents a …

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Collapse Above The World's Largest Potash Mine (Ural, Russia), Vjacheslav Andrejchuk Jan 2002

Collapse Above The World's Largest Potash Mine (Ural, Russia), Vjacheslav Andrejchuk

International Journal of Speleology

This paper reports the results of the study of a huge collapse that occurred in June 1986 within the area of the 3rd Berezniki potash mine (the Verkhnekamsky potash deposit, Ural). Processes that took place between the first appearance of a water inflow through the mine roof and the eventual collapse are reconstructed in detail. The origin and development of a cavity that induced the collapse are revealed. Two factors played a major role in the formation of the collapse: the presence of a tectonic fold/rupture zone with in both the salt sequence and the overburden (the zone of crush …

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Karstology And The Opening Of Caves During Motorway Construction In The Karst Region Of Slovenia, Martin Knez, Tadej Slabe Jan 2002

Karstology And The Opening Of Caves During Motorway Construction In The Karst Region Of Slovenia, Martin Knez, Tadej Slabe

International Journal of Speleology

The nature of karst makes constructing a roadway across karst areas a complex task, which is why karstologists take part in motorway construction across Slovenia’s karst. Working with planners, karstologists select the best route on the basis of preliminary research. Then they carry out regular karstological monitoring of the construction, to study newly discovered karst phenomena, mostly caves, and also help builders overcome the challenges of karst in a way that will preserve nature as much as possible. During the recent construction of a section of motorway, more than three hundred caves were encountered within a sixty-kilometre stretch of road. …

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Subsidence Hazards As A Consequence Of Dam, Reservoir And Tunnel Construction, Petar Milanovic Jan 2002

Subsidence Hazards As A Consequence Of Dam, Reservoir And Tunnel Construction, Petar Milanovic

International Journal of Speleology

Considering all man-made structures in karst areas, dams, reservoirs and tunnels are the most vulnerable in relation to induced subsidence and caverns. Reservoirs that are located entirely or partially on karstified rocks covered with unconsolidated sediments are especially subsidence-prone. As a consequence of induced subsidence a number of reservoirs in karst areas failed and were never fully filled. Such subsidence formation is very damaging because the development is unpredictable and practically instantaneous. Reservoirs in karst areas may fail to fill despite an extensive site investigation programs and sealing treatment. Every problem is unique and past experiences are never repeated. This …

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Karst Subsidence In South-Central Apulia, Southern Italy, Marco Delle Rose, Mario Parise Jan 2002

Karst Subsidence In South-Central Apulia, Southern Italy, Marco Delle Rose, Mario Parise

International Journal of Speleology

Subsidence in the karst of Apulia (Southern Italy), one of the classical karst areas of Italy, is described in this paper. The carbonate rocks that make up the geological structure of the Apulia region are affected by subsidence, which is of different type and intensity depending upon geological, topographical, and hydrogeological conditions. In particular, we discriminate between inland subsidence and coastal subsidence. Inland subsidence is generally restricted to the presence of individual cavities, either empty or partly or totally filled with deposits produced by dissolution of soluble rocks underground. Locally, such subsidence can cause severe effects on anthropogenic structures above. …

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