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Article: Analysis of rainstorm-induced slide-debris flows on natural terrain of Lantau Island, Hong Kong

TitleAnalysis of rainstorm-induced slide-debris flows on natural terrain of Lantau Island, Hong Kong
Authors
KeywordsColluvium
Debris flows
Hong Kong
Infiltration
Landslides
Rainfall
Issue Date1999
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/enggeo
Citation
Engineering Geology, 1999, v. 51 n. 4, p. 279-290 How to Cite?
AbstractLantau Island, the largest outlying island of the territory of Hong Kong, experienced a severe rainstorm on 4-5 November 1993, which induced >800 slope failures on natural terrain there. Detailed field investigations were carried out to study the failure modes, in relation with various influencing factors. It was found that the occurrence of slide-debris flows has a close relationship with bedrock geology, slope gradient, vegetation cover and micro landform. The failure modes of slide-debris flows may be classified into translational slides and rotational slides, and the former are predominant. Analysis of the hydrological response of colluvial slopes during the rainstorm indicated that the majority of the failures were caused by the development of a perched water table in the thin surface layer of colluvium of volcanic origin due to infiltration during the heavy rain. Undisturbed soil samples from south Lantau have been subjected to anisotropically consolidated undrained compression tests at comparatively low stress levels. Constant deviatoric stress path tests (CQD) simulating the stress path in the field at in situ stress levels have been performed to investigate soil behavior. The CQD test results indicate that the material of slopes at undisturbed state is brought to dilation because of the increase in pore water pressure caused by infiltration of rain water. For a translational slide, the displacement, resulting from dilation, may destroy cohesion along the failure surface and locally within the interior of the slide. The surplus water during the intense rainstorm was able to equilibrate the reduction in pore pressure caused by dilation, and the dilation and displacement may be further increased. The strain-softening after significant strains triggered debris flow mobilization. However, for a rotational slide, the increase in pore water pressure caused by surplus water infiltration during the intense rainstorm could not equilibrate the reduction in pore pressure caused by dilation, much or even all of the sliding block could not mobilize into a debris flow. | Lantau Island experienced a severe rainstorm on November 4-5, 1993, inducing >800 slope failures in natural terrain. Detailed field investigations were carried out to study the failure modes in relation to various influencing factors. The occurrence of slide-debris flows has a close relationship with bedrock geology, slope gradient, vegetation cover and micro-landform. The analysis of the hydrological response of colluvial slopes during the rainstorm indicated that the majority of the failures were caused by the development of a perched water table in the thin surface layer of the colluvium of volcanic origin due to infiltration during heavy rain.
Persistent Identifierhttp://hdl.handle.net/10722/70930
ISSN
2015 Impact Factor: 2.196
2015 SCImago Journal Rankings: 1.810
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorFuchu, Den_HK
dc.contributor.authorLee, CFen_HK
dc.contributor.authorSijing, Wen_HK
dc.date.accessioned2010-09-06T06:27:23Z-
dc.date.available2010-09-06T06:27:23Z-
dc.date.issued1999en_HK
dc.identifier.citationEngineering Geology, 1999, v. 51 n. 4, p. 279-290en_HK
dc.identifier.issn0013-7952en_HK
dc.identifier.urihttp://hdl.handle.net/10722/70930-
dc.description.abstractLantau Island, the largest outlying island of the territory of Hong Kong, experienced a severe rainstorm on 4-5 November 1993, which induced >800 slope failures on natural terrain there. Detailed field investigations were carried out to study the failure modes, in relation with various influencing factors. It was found that the occurrence of slide-debris flows has a close relationship with bedrock geology, slope gradient, vegetation cover and micro landform. The failure modes of slide-debris flows may be classified into translational slides and rotational slides, and the former are predominant. Analysis of the hydrological response of colluvial slopes during the rainstorm indicated that the majority of the failures were caused by the development of a perched water table in the thin surface layer of colluvium of volcanic origin due to infiltration during the heavy rain. Undisturbed soil samples from south Lantau have been subjected to anisotropically consolidated undrained compression tests at comparatively low stress levels. Constant deviatoric stress path tests (CQD) simulating the stress path in the field at in situ stress levels have been performed to investigate soil behavior. The CQD test results indicate that the material of slopes at undisturbed state is brought to dilation because of the increase in pore water pressure caused by infiltration of rain water. For a translational slide, the displacement, resulting from dilation, may destroy cohesion along the failure surface and locally within the interior of the slide. The surplus water during the intense rainstorm was able to equilibrate the reduction in pore pressure caused by dilation, and the dilation and displacement may be further increased. The strain-softening after significant strains triggered debris flow mobilization. However, for a rotational slide, the increase in pore water pressure caused by surplus water infiltration during the intense rainstorm could not equilibrate the reduction in pore pressure caused by dilation, much or even all of the sliding block could not mobilize into a debris flow. | Lantau Island experienced a severe rainstorm on November 4-5, 1993, inducing >800 slope failures in natural terrain. Detailed field investigations were carried out to study the failure modes in relation to various influencing factors. The occurrence of slide-debris flows has a close relationship with bedrock geology, slope gradient, vegetation cover and micro-landform. The analysis of the hydrological response of colluvial slopes during the rainstorm indicated that the majority of the failures were caused by the development of a perched water table in the thin surface layer of the colluvium of volcanic origin due to infiltration during heavy rain.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.subjectColluviumen_HK
dc.subjectDebris flowsen_HK
dc.subjectHong Kongen_HK
dc.subjectInfiltrationen_HK
dc.subjectLandslidesen_HK
dc.subjectRainfallen_HK
dc.titleAnalysis of rainstorm-induced slide-debris flows on natural terrain of Lantau Island, Hong Kongen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0013-7952&volume=51 &issue=4&spage=279 &epage= 290&date=1999&atitle=Analysis+of+Rainstorm-Induced+Slide-Debris+Flows+on+Natural+Terrain+of+Lantau+Island,+Hong+Kongen_HK
dc.identifier.emailLee, CF: leecf@hkucc.hku.hken_HK
dc.identifier.authorityLee, CF=rp00139en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/S0013-7952(98)00047-7en_HK
dc.identifier.scopuseid_2-s2.0-0032008455en_HK
dc.identifier.hkuros60942en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0032008455&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume51en_HK
dc.identifier.issue4en_HK
dc.identifier.spage279en_HK
dc.identifier.epage290en_HK
dc.identifier.isiWOS:000078814800003-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridFuchu, D=6507274602en_HK
dc.identifier.scopusauthoridLee, CF=8068602600en_HK
dc.identifier.scopusauthoridSijing, W=7410335510en_HK

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