ARON, G, BALL, JE & SMITH, TA 1991, 'FRACTAL CONCEPT USED IN TIME-OF-CONCENTRATION ESTIMATES', JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING-ASCE, vol. 117, no. 5, pp. 635-641.
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In present hydrologic practice, it is generally recognized that the shallow overland sheet flow through the upper portions of a watershed is very slow, and that runoff gradually accelerates as it concentrates into gullies and, finally, streams. In this paper, the fractal concept is applied by testing whether a watershed's stream-and-swale system branches in a characteristic pattern that repeats itself into successively finer but similar segments. Commonly used geometric, geomorphologic, hydraulic, and hydrologic equations are combined to reduce the number of parameters. Kinematic wave equations are then developed for the runoff movement in the channels, and integrated to obtain an equation for the time of concentration. © ASCE.
BRISCOE, BJ, STUART, BH, THOMAS, PS & WILLIAMS, DR 1991, 'A COMPARISON OF THERMAL-INDUCED AND SOLVENT-INDUCED RELAXATION OF POLY(ETHER ETHER KETONE) USING FOURIER-TRANSFORM RAMAN-SPECTROSCOPY', SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, vol. 47, no. 9-10, pp. 1299-1303.
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The paper describes a study of the application of Fourier transform Raman spectroscopy as a means of identifying the extent of the surface plasticisation of a poly(ether ether ketone) by a known plasticising solvent, toluene. Spectra are described for t
CAO, HT & SIRIVIVATNANON, V 1991, 'CORROSION OF STEEL IN CONCRETE WITH AND WITHOUT SILICA FUME', CEMENT AND CONCRETE RESEARCH, vol. 21, no. 2-3, pp. 316-324.
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Green, TK, Ball, JE & Conkright, K 1991, 'Rate of benzene sorption by O-alkylated Illinois No. 6 coal', Energy & Fuels, vol. 5, no. 4, pp. 609-610.
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Indraratna, B & Nutalaya, P 1991, 'Some engineering characteristics of a compacted lateritic residual soil', Geotechnical and Geological Engineering, vol. 9, no. 2, pp. 125-137.
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In many parts of the world, particularly in humid tropical regions, residual soils are abundant. In this paper the suitability of a residual lateritic soil as a construction material is investigated, with respect to its strength and compaction characteristics. In comparison with other typical construction fills available in Southeast Asia, compacted lateritic soils produce excellent shear strengths and CBR values. However, the brittleness and tensile cracking of this compacted material become enhanced on the dry side of the optimum moisture content, or if excessive compaction is imparted. Nevertheless, at a moisture content of 2% wetter than the optimum, the tensile mode of failure is suppressed and the lateritic fills become ideally suited for the construction of high embankments and impervious dam cores. © 1991 Chapman & Hall.
Indraratna, B, Nutalaya, P & Kuganenthira, N 1991, 'Stabilization of a dispersive soil by blending with fly ash', Quarterly Journal of Engineering Geology, vol. 24, no. 3, pp. 275-290.
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This paper is concerned with the influence of fly ash (pozzolanic) on the stabilization of a dispersive soil commonly found in northeast Thailand. The effect of various proportions of fly ash on the rate of erosion, dispersiveness, strength and frictional properties and the compaction and consolidation characteristics, are discussed. It is noted that in general the addition of fly ash not only inhibits erosion and dispersiveness but also contributes to a significant improvement in strength and deformation characteristics. Nevertheless, excessive quantities of fly ash (8%) generate diminishing returns and in fact promote segregation (erosion) of the stabilized soil again due to insufficient cohesion. Mineralogical studies based on X-ray diffraction analysis indicate that the reduction in the rate of erosion of the blended soil is associated with fine particle flocculation. The long term properties, however, are directly linked with the self-hardening nature of fly ash which contributes to time-dependent strengthening of the stabilized soil. © 1991 The Geological Society.
Indraratna, B, Nutalaya, P, Koo, KS & Kuganenthira, N 1991, 'Engineering behaviour of a low carbon, pozzolanic fly ash and its potential as a construction fill', Canadian Geotechnical Journal, vol. 28, no. 4, pp. 542-555.
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Detailed laboratory investigations were conducted on Mae Moh fly ash from northern Thailand for the determination of its grain size distribution, mineralogy, pozzolanic activity, compaction and strength characteristics, and the collapse potential. On the basis of the experimental results, this fly ash is classified as ASTM class C, which is considered to be pozzolanic. It has good potential to be utilized as an effective fill for embankments (roads and dams), airfields, pavements, and building bricks, as well as for the stabilization of compressible or erodible foundations. Because of the fact that Mae Moh fly ash contains only a negligible amount of unburned carbon, its pozzolanic reactivity is accelerated, in comparison with the relatively inert, high-carbon fly ash produced elsewhere in Thailand and many other parts of Asia. It is also demonstrated that Mae Moh fly ash can be easily compacted to produce acceptable dry densities over a wide range of water contents. Curing with an adequate moisture supply in the presence of calcium oxide plays an important role in accelerating the pozzolanic reactions, hence improving the time-dependent-properties. This study further proposes that a curing period of 2–3 weeks is sufficient for this material to approach its maximum strength. Although the behaviour of one specific fly ash cannot generalize the wide array of other ashes, the test results obtained for Mae Moh fly ash may be applied to lignite ashes in the category of ASTM class C. Key words: fly ash, structural fill, compaction, compressive strength, shear strength, collapse potential, pozzolanic activity.
Indraratna, B, Satkunaseelan, KS & Rasul, MG 1991, 'Laboratory Properties of a Soft Marine Clay Reinforced with Woven and Nonwoven Geotextiles', Geotechnical Testing Journal, vol. 14, no. 3, pp. 288-295.
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Abstract This paper is concerned with the laboratory properties of a geotextile-reinforced compacted soft marine deposit with respect to its compaction, compressive strength, and time-dependent settlement characteristics. Two different geotextiles, namely, Polyfelt TS-500 (nonwoven) and Cardon SG PP 150 (woven) have been investigated. It was observed from the experimental study that a nonwoven geotextile contributes very differently as compared to a woven geotextile when placed within soft clay soils. This is because of the fact that the nonwoven Polyfelt fabric allows better drainage (dissipation of pore pressures) in comparison with the woven Cardon geotextile, particularly at high moisture contents. The compactibility of the reinforced sample is affected by the moisture content, number of fabric layers, and the type of geotextile. With the presence of geotextiles, the compressive strength of the soil is dictated not only by the internal mode of failure induced in the samples, but also by the spacing and the drainage capacity of the geotextile layers.
LOPEZFROEDGE, L, BALL, JE, CHEN, MW & GREEN, TK 1991, 'FLORY INTERACTION PARAMETERS FOR ILLINOIS NUMBER-6 COAL EXTRACTS AND BENZENE', ACS SYMPOSIUM SERIES, vol. 461, pp. 137-158.
NWACHUKU, DA & LOGANATHAN, P 1991, 'THE EFFECT OF LIMING ON MAIZE YIELD AND SOIL PROPERTIES IN SOUTHERN NIGERIA', COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS, vol. 22, no. 7-8, pp. 623-639.
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Effects of four rates of lime applications to maize grown in 12 strongly acidic soils of southern Nigeria belonging to Ultisol and Inceptisol orders were studied under greenhouse conditions. Five of these soils (A1 saturation, 26%-33%; Ca saturation, 3%-16%) showed marked responses to lime with % relative yield (percentage of maximum yield) ranging from 5 to 73, 2 soils (A1 saturation, 1% and 5%; Ca saturation, 52% and 59%) showed no response (about 95% relative yield) and the remaining 5 soils (A1 saturation, 15%-28%; Ca saturation, 10%-31%) showed marginal responses (79% to 90% relative yield). Percent relative yield was highly correlated with initial soil values of % A1 saturation (r = 0.923), 0.02M CaCl2 soluble A1 (r = 0.906), % Ca saturation (r = 0.806) and exchangeable Ca (r = 0.729) and poorly correlated with soil pH (r = 0.559). Overall, A1 saturation, soluble Al, Ca saturation and exchangeable Ca values corresponding to 90% relative yield were 27%, 13 mg/L, 21% and 0.7 cmol(+)/kg, respectively. On an individual soil basis, near maximum yield was obtained when liming reduced the soil Al saturation to 25% and increased Ca saturation to 28%. No increase in yields was obtained by liming beyond pH 5.5. © 1991, Taylor & Francis Group, LLC. All rights reserved.
Sirivivatnanon, V & Cao, HT 1991, 'Quality assurance of concrete structures analysis of in-situ concrete cover', Transactions of the Institution of Engineers, Australia. Civil engineering, vol. CE33, no. 2, pp. 111-118.
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This paper presents a brief review of durability problems in reinforced concrete structures caused by lack of sufficient concrete cover and a statistical concept to analyse and to quantify in-situ concrete cover in buildings. The use of non-destructive procedures to measure the cover in building elements under construction is discussed. Cover data of a large number of buildings in Australia and Japan were analysed. It was found that the Levels of Confidence (LOC) for achieving minimum concrete cover for durability were poor, with less than 50 per cent of the structures achieving a 90% LOC. The use of the non-destructive technique of cover measurement and the statistical concept to quantify the in-situ cover as a quality auditing tool are described. The effectiveness of such a tool, coupled with a series of corrective measures implemented during the construction, to improve the LOC is demonstrated using an example of projects in Singapore. With improvements in design detailing, selection of suitable spacers and good installation practice, it is suggested that an LOC of 90% could be achieved and should be specified. These, together with the correct choice of the concrete type, cover thickness and good concreting practice, could prove to be the most economical way of achieving the design service life of concrete structures.
Stewart, MG 1991, 'Probabilistic risk assessment of quality control and quality assurance measures in structural design', IEEE Transactions on Systems, Man, and Cybernetics, vol. 21, no. 5, pp. 1000-1007.
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It is generally accepted that the majority of structural failures are caused by the presence of human error. A Probabilistic risk assessment approach used to examine the effects of human error on a typical structural engineering design task (design of a steel I-beam) is reported. This approach utilizes event-tree methodology and Monte-Carlo simulation analysis. An investigation of the efficiency of a quality control measure (e.g., design checking) is reported that includes design checking guidelines for the structural engineering profession. The use of safe load tables (for steel member design) as a quality assurance measure is also investigated. It is indicated that a designer using safe load tables (or similar design aids) will be more “cost-effective” and less prone to error than designers not using such design aids. Comparisons between the efficiency of design checking and the use of safe load tables will be made. © 1991 IEEE
Stewart, MG 1991, 'Safe load tables: A design aid in the prevention of human error', Structural Safety, vol. 10, no. 4, pp. 269-282.
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It is conventional wisdom that design error causes a significant proportion of structural failures. The use of safe load tables (for steel member design) as a task complexity reduction measure is investigated. The development and analysis of a model for a member design task is described in the present paper. The model uses a design sequence based on either direct use of code provisions or use of safe load tables. It is shown that the use of safe load tables reduces design time by approximately 65% (and hence cost), reduces human error in a design and leads to an increase in structural safety. The use of an 'economic decision' model found that such a design sequence is 'cost-effective' when compared to using the design codes rules directly. A model representing the checking of a designer's own work is also described. It is demonstrated that design checking further reduces the error content in a design, and can be as effective as independent checking of a design using code provisions directly. The main reason for this is the 'rounding-up' of tabulated values in the safe load tables, and this results in a design with safety levels nearer that of an 'error free' design. © 1991.
Stewart, MG & Melchers, RE 1991, 'Closure to “ Checking Models in Structural Design ” by Mark G. Stewart and Robert E. Melchers (June, 1989, Vol. 115, No. 6)', Journal of Structural Engineering, vol. 117, no. 7, pp. 2188-2189.
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Stewart, MG & Melchers, RE 1991, 'Discussion of paper', Civil Engineering Systems, vol. 8, no. 1, pp. 59-60.
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Zhou, JL & Banks, CJ 1991, 'Removal of humic acid fractions by Rhizopus arrhizus: Uptake and kinetic studies', Environmental Technology, vol. 12, no. 10, pp. 859-869.
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Zhou, JL & Banks, CJ 1991, 'The adsorption of humic acid fractions by fungal biomass', Environmental Technology, vol. 12, no. 6, pp. 519-529.
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Zhou, JL & Kiff, RJ 1991, 'The uptake of copper from aqueous solution by immobilized fungal biomass', Journal of Chemical Technology & Biotechnology, vol. 52, no. 3, pp. 317-330.
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AbstractThe removal of cupric ions from aqueous solution by a biosorption column in which the Rhizopus arrhizus fungal biomass was immobilized in reticulated foam biomass support particles was studied. Solution pH was found to be crucial to copper uptake, with the optimum range being 6·7–7·0. The removal efficiency was usually higher at low influent copper concentration and long residence time. The presence of other cations and anions inhibited copper uptake in the following order: for the cations, Mn2+ ≫ Zn2+ > Cd2+ > Mg2+ > Ca2+; for the anions, EDTA ≫ SO ≫ Cl−. The biosorption process was fully reversible and regenerated columns showed undiminished performance.
BALL, JE 1970, 'TEMPORAL PATTERN INFLUENCES ON CATCHMENT RESPONSE', NEW TECHNOLOGIES IN URBAN DRAINAGE : UDT 91, INTERNATIONAL CONF ON URBAN DRAINAGE AND NEW TECHNOLOGIES ( UDT 91 ), ELSEVIER APPL SCI PUBL LTD, DUBROVNIK, YUGOSLAVIA, pp. 135-142.
Indraratna, B & Nilaweera, S 1970, 'Seismic relationships for rockbursting using energy considerations', 7th ISRM Congress, pp. 1121-1124.
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The following paper discusses the phenomenon of rockbursitng on the basis of seismic energy release, due to the change in potential energy of deforming mine openings. A simplified analytical solution (two-dimensional) for a deep circular excavation is presented to illustrate, how the seismic energy release can be linked to the enlargement of the opening. The paper also reflects upon the empirical formulation of the relationships between the potential fault-slip bursts and the corresponding precursor time and seismic magnitudes for deep mining conditions.
LOPEZFROEDGE, L, BALL, JE, CHEN, MW & GREEN, TK 1970, 'FLORY INTERACTION PARAMETERS FOR ILLINOIS NUMBER-6 COAL EXTRACTS AND BENZENE', COAL SCIENCE II, SYMP AT THE 198TH NATIONAL MEETING OF THE AMERICAN CHEMICAL SOC : COAL SCIENCE 2, AMER CHEMICAL SOC, MIAMI BEACH, FL, pp. 137-158.
SIRIVIVATNANON, V & CAO, HT 1970, 'THE NEED FOR AND A METHOD TO CONTROL CONCRETE COVER', QUALITY CONTROL OF CONCRETE STRUCTURES, INTERNATIONAL SYMP ON QUALITY CONTROL OF CONCRETE STRUCTURES, E & FN SPON, GHENT, BELGIUM, pp. 237-246.
