File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
Supplementary

Article: Confined groundwater zone and slope instability in weathered igneous rocks in Hong Kong

TitleConfined groundwater zone and slope instability in weathered igneous rocks in Hong Kong
Authors
KeywordsClay
Confined aquifer
Factor of safety
Hydraulic conductivity
Kaolin
Saprolite
Slope stability
Weathered igneous rocks
Issue Date2005
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/enggeo
Citation
Engineering Geology, 2005, v. 80 n. 1-2, p. 71-92 How to Cite?
AbstractIn Hong Kong, slope failure in weathered granite and volcanic rocks has been studied extensively, but the impact of hydrogeological conditions on slope stability has received much less attention. It is customary in Hong Kong to assume that the hydraulic conductivity (K) of weathered igneous rocks decreases with depth or as the rock mass becomes less weathered. Generally studies of groundwater for determining slope stability treat the saprolite above the rockhead as an aquifer and the rockhead as an impermeable boundary. This paper examines direct and indirect aquifer hydraulic information scattered in various sources and demonstrates that such a model may be inappropriate. Evidence is cited to show that, at least in some places, a relatively high hydraulic conductivity (K) zone (HKZ) may exist at depth, either in the lower saprolite or at the rockhead. The completely decomposed igneous rocks, if significantly kaolinized, may have low permeability and behave as a confining zone for the HKZ. The groundwater flow regime in such an HKZ may be confined, resulting in a higher rise in water pressure in response to rainfall than might otherwise be expected. These high pressures may result in a significant reduction in slope stability. An examination of the cross-sections of some well-known landslides in Hong Kong reveals a chair-shaped rockhead profile. Numerical models coupling saturated and unsaturated subsurface flow are used to investigate the saturation process in the presence of an HKZ in slopes in response to typical rainstorms. The simplified Bishop's method is used to calculate changes in the factor of safety for slopes during such rainstorms. The saturation process and pressure distribution in a slope are complicated by the presence of an HKZ. An HKZ that is blocked at the toe represents the worst hydraulic condition for slope stability. The paper concludes that, although slope stability studies in Hong Kong have tended to focus on perching within the regolith, a critical hydraulic boundary condition may exist locally at the base of the regolith. © 2005 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/72962
ISSN
2015 Impact Factor: 2.196
2015 SCImago Journal Rankings: 1.810
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorJiao, JJen_HK
dc.contributor.authorWang, XSen_HK
dc.contributor.authorNandy, Sen_HK
dc.date.accessioned2010-09-06T06:46:45Z-
dc.date.available2010-09-06T06:46:45Z-
dc.date.issued2005en_HK
dc.identifier.citationEngineering Geology, 2005, v. 80 n. 1-2, p. 71-92en_HK
dc.identifier.issn0013-7952en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72962-
dc.description.abstractIn Hong Kong, slope failure in weathered granite and volcanic rocks has been studied extensively, but the impact of hydrogeological conditions on slope stability has received much less attention. It is customary in Hong Kong to assume that the hydraulic conductivity (K) of weathered igneous rocks decreases with depth or as the rock mass becomes less weathered. Generally studies of groundwater for determining slope stability treat the saprolite above the rockhead as an aquifer and the rockhead as an impermeable boundary. This paper examines direct and indirect aquifer hydraulic information scattered in various sources and demonstrates that such a model may be inappropriate. Evidence is cited to show that, at least in some places, a relatively high hydraulic conductivity (K) zone (HKZ) may exist at depth, either in the lower saprolite or at the rockhead. The completely decomposed igneous rocks, if significantly kaolinized, may have low permeability and behave as a confining zone for the HKZ. The groundwater flow regime in such an HKZ may be confined, resulting in a higher rise in water pressure in response to rainfall than might otherwise be expected. These high pressures may result in a significant reduction in slope stability. An examination of the cross-sections of some well-known landslides in Hong Kong reveals a chair-shaped rockhead profile. Numerical models coupling saturated and unsaturated subsurface flow are used to investigate the saturation process in the presence of an HKZ in slopes in response to typical rainstorms. The simplified Bishop's method is used to calculate changes in the factor of safety for slopes during such rainstorms. The saturation process and pressure distribution in a slope are complicated by the presence of an HKZ. An HKZ that is blocked at the toe represents the worst hydraulic condition for slope stability. The paper concludes that, although slope stability studies in Hong Kong have tended to focus on perching within the regolith, a critical hydraulic boundary condition may exist locally at the base of the regolith. © 2005 Elsevier B.V. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/enggeoen_HK
dc.relation.ispartofEngineering Geologyen_HK
dc.rightsEngineering Geology. Copyright © Elsevier BV.en_HK
dc.subjectClayen_HK
dc.subjectConfined aquiferen_HK
dc.subjectFactor of safetyen_HK
dc.subjectHydraulic conductivityen_HK
dc.subjectKaolinen_HK
dc.subjectSaproliteen_HK
dc.subjectSlope stabilityen_HK
dc.subjectWeathered igneous rocksen_HK
dc.titleConfined groundwater zone and slope instability in weathered igneous rocks in Hong Kongen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0013-7952&volume=80&issue=1-2&spage=71&epage=92&date=2005&atitle=Confined+groundwater+zone+and+slope+instability+in+weathered+igneous+rocks+in+Hong+Kongen_HK
dc.identifier.emailJiao, JJ:jjiao@hku.hken_HK
dc.identifier.authorityJiao, JJ=rp00712en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.enggeo.2005.04.002en_HK
dc.identifier.scopuseid_2-s2.0-23044463047en_HK
dc.identifier.hkuros120807en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-23044463047&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume80en_HK
dc.identifier.issue1-2en_HK
dc.identifier.spage71en_HK
dc.identifier.epage92en_HK
dc.identifier.isiWOS:000231819000005-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridJiao, JJ=7102382963en_HK
dc.identifier.scopusauthoridWang, XS=8118576100en_HK
dc.identifier.scopusauthoridNandy, S=36831918300en_HK

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats