Subsidence hazards caused by the dissolution of Permian gypsum in England : geology, investigation and remediation
Cooper, A.H.. 1998 Subsidence hazards caused by the dissolution of Permian gypsum in England : geology, investigation and remediation. In: Maund, J.G.; Eddleston, M., (eds.) Geohazards in engineering geology. London, UK, Geological Society of London, 265-275. (Special Publications in Engineering Geology, 15).Before downloading, please read NORA policies.
RIPON_1998_Final with colour figs recompiled.pdf
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About every three years natural catastrophic subsidence, caused by gypsum dissolution, occurs in the vicinity of Ripon, North Yorkshire, England. Holes up to 35 m across and 20 m deep have appeared without warning. In the past 150 years, 30 major collapses have occurred, and in the last ten years the resulting damage to property is estimated at about £1000000. Subsidence, associated with the collapse of caves resulting from gypsum dissolution in the Permian rocks of eastern England, occurs in a belt about 3 km wide and over 100 km long. Gypsum (CaS04.2H20) dissolves rapidly in flowing water and the cave systems responsible for the subsidence are constantly enlarging, causing a continuing subsidence problem. Difficult ground conditions are associated with caves, subsidence breccia pipes (collapsed areas of brecciated and foundered material), crown holes and post-subsidence fill deposits. Site investigation methods that have been used to define and examine the subsidence features include microgravity and resistivity geophysical techniques, plus more conventional investigation by drilling and probing. Remedial measures are difficult, and both grouting and deep piling are not generally practical. In more recent times careful attention has been paid to the location for development and the construction of low-weight structures with spread foundations designed to span any subsidence features that may potentially develop.
|Item Type:||Book Section|
|Programmes:||BGS Programmes > Physical Hazards|
|NORA Subject Terms:||Earth Sciences|
|Date made live:||20 May 2011 08:51|
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