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Collaborating Authors
Earthquake
ABSTRACT A case history of a cast-in-place concrete pile foundation that experienced liquefaction-induced lateral flow during the 1995 Hyogoken-Nambu earthquake is examined. The field investigations conducted after the earthquake show that: (1) the piles above a depth of 15 m were displaced southeastwards by at least 90 cm; (2) concrete cracking concentrated at depths smaller than 6 m and at depths of 12-15 m; (3) in the longitudinal direction, the east-side piles inclined westwards while the west-side piles inclined eastwards; (4) in the span direction, all the piles inclined southwards, and (5) vertical cracking on the footing beams in the longitudinal direction is more extensive than that in the span direction. Based on pseudo-static analyses, it is shown that: (1) the computed failure and deformation modes match reasonable well with the field behavior when both the maximum earth pressure and the coefficient of horizontal subgrade reaction of piles in laterally-spreading soils are 0.15 times those of the non-liquefied soil; and (2) the different failure and deformation modes of piles within the foundation is caused by spatial variation of horizontal ground displacement within the site. INTRODUCTION The 1995 Hyougoken-Nambu earthquake caused extensive damage to piles (e.g., AIJ, 1998; BTL, 1998). Various field investigations and analyses conducted after the earthquake have indicated that the kinematic force from liquefied and laterally-spreading soils as well as the inertial force from superstructures was the major cause of the damage. The kinematic load is believed to have dominated where liquefaction-induced lateral spreading occurred; however, its effect has only been cited qualitatively, because of scarcity of pile damage resulting from lateral spreading alone.
ABSTRACT: This paper describes the findings of an experimental study into the behavior of saturated sands under high initial effective confining stresses subjected to strong ground shaking. Support for the research was by the U.S. Army Centrifuge Research Center and Engineer Earthquake Engineering Research Program (EQEN). The research was conducted using the U.S. Army Centrifuge, located in Vicksburg MS. The centrifuge studies have shown that the generation of excess pore pressure is capped at a level below 100% for vertical effective confining stresses exceeding around 3 atmospheres (atm, or 300 KPa). This limit reduces at higher confining stresses. Predictions of seismic behavior, analyses and design of remediation works for large earth dams could be substantially benefited, when the findings are verified. The paper describes in outline the equipment used for the experiments, the research program, and presents the initial results. A hypothetical example of an embankment design is discussed illustrating the beneficial effects of these findings on the predicted response, with consequences for the remediation design. INTRODUCTION The current state-of-practice for the evaluation of liquefaction potential and for remediation design and analysis depends on empirical correlations of in-situ measurements of strength versus field experience of liquefaction at shallow depth and laboratory data of the behavior of confined elements under cyclic loading. (Liquefaction is defined here as pore pressure equal to 100% of the initial vertical effective stress.) This approach is known as the "simplified procedure". In practice, the seismic response of saturated soil under high initial confining stress is not well understood. Hence, in design practice the assessment of liquefaction under these conditions, such as might relate to the foundations of large earth dams, is based on the extrapolation of observed behavior and correlations at shallow depths, Youd and Idriss (1997).
- Research Report > New Finding (0.34)
- Research Report > Experimental Study (0.34)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (1.00)
- Geology > Geological Subdiscipline (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.55)
ABSTRACT: Many flood protection dikes were damaged in both eastern and western Hokkaido, Japan during large earthquakes in 1993 and 1994 due to liquefaction in the foundations. A criterion based on crest settlement was developed for prioritizing remediation of the diking system to resist future earthquakes. The potential crest settlement during earthquakes of M=7.5 to M=8.0 was expressed in terms of geometrical properties of the dike cross-section. The procedure used to estimate the settlements was first used to simulate dike failures in eastern Hokkaido. Then, blind prediction tests were carried out for typical dikes in western Hokkaido. These predictions were then checked against actual field performance. The criterion proved to be very effective in predicting the performance of the damaged dikes. INTRODUCTION Flood protection dikes along the Kushiro and Tokachi rivers suffered considerable damage during the 1993 Kushiro-oki earthquake off eastern Hokkaido, Japan. Damage included longitudinal and transverse cracks, slope failures and cave-ins. The more severely damaged dike sections were 6 m – 8 m high, and were constructed of compacted sand fill resting on a comparatively thick peat layer. Figure 1 illustrates a typical failure mode in at a cross-section of the dike on the left bank of the Kushiro River between stations 9K400 and 9K850. The failure mechanism illustrated in Fig. 1 is adapted from Sasaki et al. (1995). In 1994, a major earthquake occurred off the west coast of Hokkaido, the Nansei-oki earthquake, which caused failures of flood protection dikes along several river basins in western Hokkaido. After these earthquakes, the Hokkaido Development Bureau initiated a program of improving the diking systems. Because of the great length of dikes, they wished to develop a criterion for prioritizing the remediation work. One of the approaches they adopted was to use potential crest settlements as a criterion.
- Asia > Japan > Hokkaidō (1.00)
- North America > Canada > British Columbia > Metro Vancouver Regional District > Vancouver (0.15)
Numerical Modeling Of Landslide In Intensive Seismic Zone
Lianjin, Tao (Beijing Polytechnic University) | Zhuoyuan, Zhang (Chengdu University of Technology) | Hanchao, Liu (Chengdu University of Technology) | Hejun, Chai (Chengdu University of Technology) | Ronggui, Deng (Southwest Jiaotong University)
ABSTRACT: Landslide in intensive seismic zone has its peculiar features. Some slope may be stable under static load (normal state). When the slope is in limit equilibrium state, even a slight earthquake may trigger it to destabilize. An intensive earthquake may directly cause a whole slope to fail. Kangding City is located in the intersection of three famous active seismic belts and thus with frequent earthquake activity. Many earthquakes occurred there in the past and the basic earthquake intensity is IX degree. Frequent earthquake activity directly influences the slope stability in the region, earthquake is the key factor inducing landslide and rockfall. In view of this, dynamic discrete element method (DDEM) is adopted in analyzing the stability of a slope in Kangding City, emphasis is laid on modeling of seismic effects on slope stability. The modeling results indicate that even an earthquake with intensity V degree is enough to cause the front slope to slide, earthquake with intensity IX degree will makes the whole slope to fail and slide. The harnessing engineering is quite effective to earthquake with intensity less than V degree. However, when earthquake with intensity IX degree occurs, the bolting engineering in the steep part will be destroyed first and then the slide-resistant piles and finally the whole slope. INTRODUCTION Baitukan landslide is situated at the east slope of Shaoxiangping, along the left bank of Zeduo river in the vicinity of Kangding City, which is located at the intersection of three active seismic belts, thus with frequent earthquake activities. The landslide is an old rockslide of tremendous dimension. Its length is about 600m and width is about 1300 m. Due to lateral erosion of the Zeduo River, the frontal part of the landslide deposits failed frequently. On 15th June 1995, Kangding City hit by a strong rainstorm.
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.55)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.47)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (0.46)
ABSTRACT: Damage to pile foundations due to liquefaction-induced ground flow during past earthquakes is reviewed. Then, studies of the behaviour of pile and raft foundations in liquefied and flowed ground are surveyed, and current design methods for foundations introduced. Although several design methods have been proposed recently, it is concluded that that further studies are necessary to establish definitive methods for the design of piled foundations in liquefiable ground. 1. INTRODUCTION The liquefaction of loose sandy ground during earthquakes often causes severe damage to structures, for example, through the settlement of buildings induced by loss of soil strength. Moreover, if the ground has a gentle slope or faces a waterfront, the liquefied ground tends to flo\v, often causing extreme damage such as the collapse of pile foundations. The surest way to avoid damage is by improving the sandy soil so it will not liquefy, by densification or cementation methods. For example, the use of sand compaction piles, dynamic compaction, compaction grouting and deep cement mixing methods can prevent the occurrence of liquefaction. Furthermore, if the design input earthquake motion is very strong, it is difficult to prevent the occurrence of liquefaction by some soil improvement methods. For this situation, and as an alternative to costly soil improvement, it is desirable to develop alternative, more rational, design methods in which the occurrence of liquefaction is accepted but the structure is designed to survive it without damage. Some methods for the design of pile foundations in liquefied ground had already been developed before the 1995 Hyogoken-nambu (Kobe) earthquake in Japan. However, as many pile foundations suffered severe damage due to liquefaction and liquefaction-induced ground flow during the Hyogoken-nambu earthquake, the mechanisms of damage and design methods have been studied more intensively since then.
- Asia > Japan (1.00)
- Asia > Middle East > Turkey (0.28)
- North America > United States > Texas > Permian Basin > Norman Field > Ellenburger Formation (0.98)
- Asia > Japan > Honshu Island > Akita Basin (0.89)
Numerical Methods for Wave Equations in Geophysical Fluid Dynamics by Dale Durran. ISBN 0-387-98376-7. Springer, 1999. 465 p. $49.95.Groundwater in Geologic Processes by Steven E. Ingebritsen and Ward E. Sanford. ISBN 0-521-66400-4. Cambridge, 1999. 341 p. $32.95 (paperback).The Remote Sensing Data Handbook by Gareth Rees. ISBN 0-521-48040-X. Cambridge, 1999. 262 pp. $39.95Mesozoic and Cenozoic Sequence Stratigraphy of European Basins (SEPM Special Publication No. 60), edited by Pierre-Charles De Graciansky, Jan Hardenbol, Thierry Jacquin, and Peter R. Vail. ISBN 1-56576-043-3. SEPM, 1998. 786 pp. $175 (members $125).
- North America > United States (0.90)
- Europe > Italy > Friuli Venezia Giulia > Trieste Province > Trieste (0.25)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics (0.32)
ABSTRACT ABSTRACT: This paper introduces a method to evaluate the mechanical effects induced in the cross-section of an underground structure, constructed in a medium of great thickness, under earthquake ground motion. Damage observations after large earthquakes (e.g., Kobe, 1995) have shown the cross-sectional vulnerability of underground structures at shallow or great depth. Present earthquake-resistant design standards only suggest calculation methods for structures constructed in a soil laying over a rigid basement and cannot be applied to a structure constructed in a medium of great thickness, such as a tunnel, an underground hydrocarbon storage facility or a nuclear-waste disposal site. Thus, development of a systematic method to evaluate the seismic effects induced in the cross-section of a structure in an unbounded medium is of interest. The approach proposed here is conceptually similar to that used for earthquake response analysis of buildings: using a simple but realistic model of an underground linear structure (a 2D cavity with circular cross-section in an infinite, elastic, linear, homogeneous and isotropic medium) and real earthquake records, we propose a response spectrum more suitable, than the usual velocity or acceleration response spectrum, for analyzing the structural stability of underground construction during earthquakes: the Stress Response Spectrum (SRS), which is defined as the maximum value of the maximum shear stress at the cavity wall during the duration of ground motion. The SRS values are computed by using 21 earthquake motions (provided by the Japan Meteorological Agency) of magnitude higher than 4, which were recorded by the Japan Nuclear Cycle Research Institute (JNC) in a 315-meter deep gallery excavated in an a granodioritic rock mass at the Kamaishi Mine in Iwate, Japan. In light of the numerical analysis, the SRS appears to be a potential tool for the earthquake-response analysis of underground structures. The Stress Response Spectrum will provide engineers with the order of magnitude of mechanical effects in an underground structure for a given earthquake motion; conversely, for a given target SRS, may assist in producing a design earthquake more suitable for analysis of deep underground structures than those currently available.
- Water & Waste Management > Solid Waste Management (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Power Industry > Utilities > Nuclear (0.34)
ABSTRACT ABSTRACT: A probabilistic assessment of the possible formation of key blocks within the potential repository horizon has been performed based on the orientations of discontinuities present in the Exploratory Studies Facility at Yucca Mountain, Nevada. A primary objective of the key block analysis is to provide a statistical description of block sizes formed by fractures around the emplacement drifts openings. This analysis has considered various emplacement drift orientations, examined unsupported drifts, and applied both static and seismic loading conditions. The use of key block theory provides a practical tool for assessing rock mass behavior surrounding emplacement drift openings. The results from this study provide block size data to support waste package design and provide degraded drift profile data to support other repository performance assessment analyses.
- Geology > Geological Subdiscipline (0.47)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.31)
Two major causes of damage have been identified for the Go1ctik earthquake: fault rupture and liquefaction. The Republic of Turkey is an earthquake-prone Local geology played a very important role country with hundreds of quakes each year. Most of in liquefaction and related phenomena (flow liquefaction, these earthquakes occur on four fault systems: the cyclic mobility and level-ground liquefaction). North and East Anatolian Faults, characterized by The cities in the earthquake area are situated strike-slip movements; the western Anatolia fault over lake-bed sediments or old river beds that contain system, characterized by normal faulting; and the layers of silts and sands subject to liquefaction. Bitlis fault zone in eastern Turkey, characterized by The majority of buildings in these cities were completely thrust faulting. Major earthquakes that occurred in or partially destroyed because of extensive 1999 in Turkey (Golctik) and Taiwan, and the 1995 liquefaction of the soil resulting from strong ground earthquake in Kobe, Japan, are all located on faults motion. Buildings in the same area (just as close to that are at the boundaries of the Euro-Asian plate.
- Asia > Middle East > Turkey > Bitlis Province > Bitlis (0.24)
- Asia > Japan > Kansai > Hyōgo Prefecture > Kobe (0.24)
ABSTRACT In order to clarify the effect of earthquake on the behavior of offshore structures in ice-covered waters, analyses and experiments have been performed as a research project of the Japan Ocean Industries Association. Ice-covered waters are classified into four categories of sea ice states, and seismic load upon fixed offshore structures under these categories of ice states is evaluated. Earthquake induces dynamic water pressure, which increases greatly by the ice sheet attached around the offshore structure. The dynamic pressure vanishes, however, by breaking the ice at the wall of the structure. The results are being used for preparation of a guideline for seismic design of offshore structures in icecovered waters. INTRODUCTION In some locations, ice covered waters overlap with earthquake zones where ice-resistant and seismic offshore structures are required. It is not seldom that earthquake occurs in wintertime and offshore structures suffer both due to ice and seismic loads. One of the important but uncertain designs conditions for fixed offshore structures constructed in ice-covered waters may be the seismic load. There is no design rule or recommendation for seismic design of offshore structures constructed in ice-covered waters, but only some description, for example in API (1995), CSI (1992), of special consideration on earthquake for the response of iceresistant structures. The Japan Ocean Industries Association has organized a working group lbr investigation of earthquake effect on oflghore structures in ice-covered waters. Conceptual design of offshore oil production platform has been performed to identify research items and themes. Analyses and experiments have been performed to investigate the behavior of the platform under both ice and earthquake conditions. This paper presents the results of the research obtained so far. RESEARCH PROCESS 1. Conceptual design Conceptual design of oil production platform was performed under predetermined design conditions and functions of the platform.