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Disclosure of active faults in dam foundations
157A related to the age of the slopes and their process of formation. Geomorphic and geomechanical evaluation of the slopes is useful to dam foundation assessment.
Earthquake mechanisms and effects 884017 Effects of canyon topography and geological conditions on strong ground motion Zhang Chuhan; Zhao Chongbin Eart&l Engng Struet Dynam VI6. NI. Jan 1988. P81-97 The finite and infinite element coupling system is used to study the effects of canyon topography and geological conditions on strong ground motion, The system is first applied to a semicylindrical shaped canyon using SH wave propagation to verify its accuracy. It is concluded that different topography conditions may have important effects on the ground motions along the canyon. Different softening of weathered strata will have significantly amplified effects on the free field motions, suggesting that a deep weathered rock excavation of arch dam abutments for stability purposes will also benefit earthquake resistance of the dam due to reduction of ground motions of the sound rock. Auth. 884018 Simulation of earthquake sequences Chen. YT; Knopoff, L Geophys J R Astr Soc Vgl. N3. Dec 1987. P693-709 A model which simulates an earthquake sequence as a complex extension of a shear crack in a viscoelastic medium under the influence of nonuniform stress is presented. The model uses a viscoelastic rhcology of the medium with inhomogeneity of stresses to explain pre- and post-seismic creep, and stopping of the crack, as well as the variety of earthquake sequences.
884019 Earthquake risk and fracture statistics Kittl, P: Diaz, G Phys Earth Planet Inter 1:49. N3-4, Dec 1987. P222-224 On the basis of fracture statistics, which establishes a relation between the cumulative probability of fracture in a brittle body and stress field to which it is subjected, it is possible to describe some seismological statistics. The cumulative probability of time intervals between two consecutive strong earthquakes and the cumulative probability of the strong earthquakes magnitude appears as Weibullian. Comparison with Chilean set data gives evidence to the theory. Auth. 884020 Potential movements of the El Tigre fault and its effects on hydroelectric projects in the San Juan Province, Argentina (In French) Bastias, H E: Puigdomenech. H H Proc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2. PI333-1336. Publ Rotterdam: A A Balkema. 1986 The El Tigre fault is the biggest quaternary structure on the west boundary of the Precordillera geological province. It has been active in historic and holocene times, and could generate another large earthquake in the future. Using data from the last holocene movement, the magnitude and ground accelerations possible for the next event, and their effect on local hydroelectric projects are estimated.
884021 Seismotectonic hazard evaluation for the Kawarau River power development, Central Otngo, New Zealand Hancox. G T; Beanland. S; Brown, I R Proc Jth International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2, P1347-1357. Publ Rotterdam: A A Balkema. 1986 The Kawarau valley region has active faults which indicate repeated large earthquakes in the past 500,000 years. Proposed developments may be in danger due to earthquake action or reservoir induced seismicity. Using geological (fault activity) data, the probabilities of large earthquakes have been calculated to range from low to extremely low, with maximum magnitude 7.4. Vertical and horizontal accelerations evaluated are unlikely to have significant effects on most sites on schist bedrock, Reservoir induced seismicity is thought unlikely. Scismotectonic hazards overall are extremely low to low.
884O22 Dilatancy and water-hammer pattern of reservoir-induced seism Jin Zunshan; Kang Yuyun Proc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2, P1359-1365. Publ Rotterdam: A A Balkema. 1986 A mechanism for reservoir induced seismicity is proposed where energy is stored as increased pore water pressure resulting from dilatancy following fracture formation. Sudden movement on a fault releases this energy, the water hammer effect. The structural requirements for this phenomenon are an inclusion area on a fault zone and connected by a passage to the reservoir water to form a new water system. 884023 Methods of investigation in seismo-tectonic problems in the area of Longyang Gorge Hydro-electrical Power Station, China Wang Shitian; Li Yusheng; Shu Daogang; Wei Lunwu Proc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 1:2. P1379-1390. Publ Rotterdam: A A Balkema, 1986 Microseisms have occurred in the surrounding area each flood season since the cofferdams for the power station were completed. Data from regional surveys, historical records, investigations on active faults, and phenomena caused by ancient earthquakes have been analysed to identify earthquake mechanisms and potential dangers. A map of the current geostressdeformation field in the area is derived, which has been verified by physical and mathematical modelling.
884024 Disclosure of active faults in dam foundations
Varga, A A Prnc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2. PI391-1397. Publ Rotterdam: A A Balkema, 1986 Fault movements may be characterised as seismogenic, slow tectonic, slow exotectonic (salt domes), technogenie (oil reservoir depletion), or gravity seismotectonic. Only active faults are dangerous, but to class a fault as active on the basis of an arbitrary time since last activity is unsatisfactory. Instead of this, a procedure based on comprehensive engineering geology mapping, precise geodetic measurement, seismic microzoning and stratigraphic analysis is proposed.
1988 Pergamon Press plc. Reproduction not permitted
Earthquake mechanisms and effects 884017 Effects of canyon topography and geological conditions on strong ground motion Zhang Chuhan; Zhao Chongbin Eart&l Engng Struet Dynam VI6. NI. Jan 1988. P81-97 The finite and infinite element coupling system is used to study the effects of canyon topography and geological conditions on strong ground motion, The system is first applied to a semicylindrical shaped canyon using SH wave propagation to verify its accuracy. It is concluded that different topography conditions may have important effects on the ground motions along the canyon. Different softening of weathered strata will have significantly amplified effects on the free field motions, suggesting that a deep weathered rock excavation of arch dam abutments for stability purposes will also benefit earthquake resistance of the dam due to reduction of ground motions of the sound rock. Auth. 884018 Simulation of earthquake sequences Chen. YT; Knopoff, L Geophys J R Astr Soc Vgl. N3. Dec 1987. P693-709 A model which simulates an earthquake sequence as a complex extension of a shear crack in a viscoelastic medium under the influence of nonuniform stress is presented. The model uses a viscoelastic rhcology of the medium with inhomogeneity of stresses to explain pre- and post-seismic creep, and stopping of the crack, as well as the variety of earthquake sequences.
884019 Earthquake risk and fracture statistics Kittl, P: Diaz, G Phys Earth Planet Inter 1:49. N3-4, Dec 1987. P222-224 On the basis of fracture statistics, which establishes a relation between the cumulative probability of fracture in a brittle body and stress field to which it is subjected, it is possible to describe some seismological statistics. The cumulative probability of time intervals between two consecutive strong earthquakes and the cumulative probability of the strong earthquakes magnitude appears as Weibullian. Comparison with Chilean set data gives evidence to the theory. Auth. 884020 Potential movements of the El Tigre fault and its effects on hydroelectric projects in the San Juan Province, Argentina (In French) Bastias, H E: Puigdomenech. H H Proc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2. PI333-1336. Publ Rotterdam: A A Balkema. 1986 The El Tigre fault is the biggest quaternary structure on the west boundary of the Precordillera geological province. It has been active in historic and holocene times, and could generate another large earthquake in the future. Using data from the last holocene movement, the magnitude and ground accelerations possible for the next event, and their effect on local hydroelectric projects are estimated.
884021 Seismotectonic hazard evaluation for the Kawarau River power development, Central Otngo, New Zealand Hancox. G T; Beanland. S; Brown, I R Proc Jth International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2, P1347-1357. Publ Rotterdam: A A Balkema. 1986 The Kawarau valley region has active faults which indicate repeated large earthquakes in the past 500,000 years. Proposed developments may be in danger due to earthquake action or reservoir induced seismicity. Using geological (fault activity) data, the probabilities of large earthquakes have been calculated to range from low to extremely low, with maximum magnitude 7.4. Vertical and horizontal accelerations evaluated are unlikely to have significant effects on most sites on schist bedrock, Reservoir induced seismicity is thought unlikely. Scismotectonic hazards overall are extremely low to low.
884O22 Dilatancy and water-hammer pattern of reservoir-induced seism Jin Zunshan; Kang Yuyun Proc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2, P1359-1365. Publ Rotterdam: A A Balkema. 1986 A mechanism for reservoir induced seismicity is proposed where energy is stored as increased pore water pressure resulting from dilatancy following fracture formation. Sudden movement on a fault releases this energy, the water hammer effect. The structural requirements for this phenomenon are an inclusion area on a fault zone and connected by a passage to the reservoir water to form a new water system. 884023 Methods of investigation in seismo-tectonic problems in the area of Longyang Gorge Hydro-electrical Power Station, China Wang Shitian; Li Yusheng; Shu Daogang; Wei Lunwu Proc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 1:2. P1379-1390. Publ Rotterdam: A A Balkema, 1986 Microseisms have occurred in the surrounding area each flood season since the cofferdams for the power station were completed. Data from regional surveys, historical records, investigations on active faults, and phenomena caused by ancient earthquakes have been analysed to identify earthquake mechanisms and potential dangers. A map of the current geostressdeformation field in the area is derived, which has been verified by physical and mathematical modelling.
884024 Disclosure of active faults in dam foundations
Varga, A A Prnc 5th International Congress International Association of Engineering Geology, Buenos Aires, 20-25 October 1986 V2. PI391-1397. Publ Rotterdam: A A Balkema, 1986 Fault movements may be characterised as seismogenic, slow tectonic, slow exotectonic (salt domes), technogenie (oil reservoir depletion), or gravity seismotectonic. Only active faults are dangerous, but to class a fault as active on the basis of an arbitrary time since last activity is unsatisfactory. Instead of this, a procedure based on comprehensive engineering geology mapping, precise geodetic measurement, seismic microzoning and stratigraphic analysis is proposed.
1988 Pergamon Press plc. Reproduction not permitted