Evaluation of landslide triggering mechanisms in model fill slopes   总被引：7，自引：4，他引：3  

W.?A.?TakeEmail author  M.?D.?Bolton  P.?C.?P.?Wong  F.?J.?Yeung 《Landslides》2004,1(3):173-184

Hong Kong is particularly susceptible to landslide risk due to the steep natural topography and prolonged periods of high intensity rainfall. Compounding the risk of slope failure is the existence of loose fill slopes which were constructed prior to the 1970s by end-tipping. A clear understanding of the underlying triggering mechanisms of fast landslides in fill slopes is required to analyse landslide risk and to optimise slope stabilisation strategies. The work described here had the objective of evaluating two candidate triggering mechanisms—static liquefaction and the transition from slide to flow due to localised transient pore water pressures—against observations of slope behaviour obtained from highly instrumented centrifuge model tests. These results indicate that static liquefaction is unlikely to occur if the model fill is unsaturated and the depth to bedrock large, as the high compressibility and mobility of air in the unsaturated void spaces allows the model fill slope to accommodate wetting collapse without initiating undrained failure. In contrast, high-speed failures with low-angle run-outs are shown to be easily triggered in model fill slopes from initially slow moving slips driven by localised transient pore water pressures arising from constricted seepage and material layering.  相似文献   

Studying fractal geometry on submicron length scales by small-angle scattering     

Po-zen Wong  Jar-shyong Lin 《Mathematical Geology》1988,20(6):655-665

Recent studies have shown that internal surfaces of porous geological materials, such as rocks and lignite coals, can be described by fractals down to atomic length scales, In this paper, the basic properties of self-similar and self-affine fractals are reviewed and how fractal dimensions can be measured by small-angle scattering experiments are discussed.This paper was presented at Emerging Concepts, MGUS-87 Conference, Redwood City, California, 13–15 April 1987.  相似文献   

The oxidation state diagram: Additional comments     

George T.F. Wong 《Marine Chemistry》1981,10(5):461-463

The oxidation state diagram provides additional information that cannot be readily discerned from an activity ratio—pE diagram. A theoretical framework for explaining the existence of thermodynamically unstable species becomes available.  相似文献   

A Two-Dimensional Spectrum for Bistatic SAR Processing Using Series Reversion   总被引：11，自引：0，他引：11  

Neo  Y. L. Wong  F. Cumming  I. G. 《Geoscience and Remote Sensing Letters, IEEE》2007,4(1):93-96

This letter derives the two-dimensional point target spectrum for an arbitrary bistatic synthetic aperture radar configuration. The method described makes use of series reversion, the method of stationary phase, and Fourier transform pairs to derive the point target spectrum. The accuracy of the spectrum is controlled by keeping enough terms in the two series expansions, and is verified with a point target simulation  相似文献   

Aeolian sediment transport on a human‐altered foredune     

Karl F. Nordstrom  Nancy L. Jackson  Jean Marie Hartman  Mark Wong 《地球表面变化过程与地形》2007,32(1):102-115

Changes in wind speed and sediment transport are evaluated at a gap and adjacent crest of a 2 to 3 m high, 40 m wide foredune built by sand fences and vegetation plantings on a wide, nourished fine sand beach at Ocean City, New Jersey. Anemometer masts, cylindrical sand traps and erosion pins were placed on the beach and dune during two obliquely onshore wind events in February and March 2003. Results reveal that: (1) changes in the alongshore continuity of the beach and dune system can act as boundaries to aeolian transport when winds blow at an angle to the shoreline; (2) oblique winds blowing across poorly vegetated patches in the dune increase the potential for creating an irregular crest elevation; (3) transport rates and deflation rates can be greater within the foredune than on the beach, if the dune surface is poorly vegetated and the beach has not had time to dry following tidal inundation; (4) frozen ground does not prevent surface deflation; and (5) remnant sand fences and fresh storm wrack have great local but temporary effect on transport rates. Temporal and spatial differences due to sand fences and wrack, changes in sediment availability due to time‐dependent differences in surface moisture and frozen ground, combined with complex topography and patchy vegetation make it difficult to specify cause–effect relationships. Effects of individual roughness elements on the beach and dune on wind flow and sediment transport can be quantified at specific locations at the event scale, but extrapolation of each event to longer temporal and spatial scales remains qualitative. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Inertial gravimetry—A comparison of Kalman filtering-smoothing and post-mission adjustment techniques     

R. Forsberg  A. A. Vassiliou  K. P. Schwarz  R. V. C. Wong 《Journal of Geodesy》1986,60(2):129-142

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The old alluvium of Singapore and the extinct drainage system to the South China Sea     

Avijit Gupta  Ausafur Rahman  Wong Poh Poh  John Pitts 《地球表面变化过程与地形》1987,12(3):259-275

In both sand quarry faces and boreholes the Old Alluvium of Singapore is a matrix supported pebbly sand with minor beds of better sorted sands and clays. The beds can be grouped into four textural classes (pebbles, coarse sand with fine pebbles, medium to coarse sand, clay, and silt), each with characteristic sedimentary structures. The deposit appears to be the proximal facies of an ancient braided river alluvium of possible Pleistocene age. This widespread but scattered alluvium is found both on land and offshore on the Sunda Shelf in Southeast Asia. It is believed to have been deposited during low sea levels. In Singapore, the mineralogy of the grains forming the Old Alluvium suggests a mixed provenance of granitic and low-grade metamorphic origin. The volume and freshness of the deposited material indicate an environment of considerable relief, seasonal rainfall, and extremely active erosional processes, conditions considerably different from the current ones. The Old Alluvium was probably deposited by seasonal rivers which experienced periodic large floods. Such regional conditions could have prevailed over much of Southeast Asia at the time of deposition of the Old Alluvium.  相似文献   

A feature based method for tracking mesoscale rainfall areas in radar images     

J. D. Bonser  A. K. C. Wong 《Stochastic Environmental Research and Risk Assessment (SERRA)》1987,1(3):185-198

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Biological markers from Green River kerogen decomposition     

A.K. Burnham  J.E. Clarkson  M.F. Singleton  C.M. Wong  R.W. Crawford 《Geochimica et cosmochimica acta》1982,46(7):1243-1251

Isoprenoid and other carbon skeletons that are formed in living organisms and preserved essentially intact in ancient sediments are often called biological markers. The purpose of this paper is to develop improved methods of using isoprenoid hydrocarbons to relate petroleum or shale oil to its source rock. It is demonstrated that most, but not all, of the isoprenoid hydrocarbon structures are chemically bonded in kerogen (or to minerals) in Green River oil shale. The rate constant for thermally producing isoprenoid, cyclic, and aromatic hydrocarbons is substantially greater than for the bulk of shale oil. This may be related to the substantial quantity of CO₂ which is evolved coincident with the isoprenoid hydrocarbons but prior to substantial oil evolution. Although formation of isoprenoid alkenes is enhanced by rapid heating and high pyrolysis temperatures, the ratio of isoprenoid alkenes plus alkanes to normal alkenes plus alkanes is independent of heating rate. High-temperature laboratory pyrolysis experiments can thus be used to predict the distribution of aliphatic hydrocarbons in low temperature processes such as in situ shale oil production and perhaps petroleum formation. Finally, we demonstrate that significant variation in biological marker ratios occurs as a function of stratigraphy in the Green River formation. This information, combined with methods for measuring process yield from oil composition, enables one to relate time-dependent processing conditions to the corresponding time-dependent oil yield in a vertical modified-in situ retort even if there is a substantial and previously undetermined delay in drainage of shale oil from the retort.  相似文献   

Study of a Wind Front over the Northern South China Sea Generated by the Freshening of the North-East Monsoon     

Werner Alpers  Wai Kin Wong  Knut-Frode Dagestad  Pak Wai Chan 《Boundary-Layer Meteorology》2015,157(1):125-140

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