Eigenbrod, KD, Knutsson, S & Sheng, D 1991, 'Measurement of pore water pressures in freezing and thawing soft, fine grained soils', Canadian Geotechnical Conference, no. pt 1.
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Laboratory freezing tests were performed on laterally confined samples of lightly overconsolidated fine grained soil, exposed to one-dimensional freezing at a constant temperature gradient. Pore water pressures and temperatures were measured at the perimeter of the specimens at various points along their height, during freezing and thawing. Vertical heave and water in- and outflow in the sample were also recorded. X-ray pictures were taken at various points during freezing to correlate ice lens formation to the measured data. Of particular interest were occurences of high pore water pressures shortly after the freezing front had stabilized. Subsequently cyclic increases and decreases of pore water pressures, and in- and outflow were observed. During thawing sudden temperature increases were accompanied by sudden decreases of pore water pressures. The hydraulic conductivity of the unfrozen fringe was directly determined from the measured pore water pressure and temperature profiles, records of water in- and outflow, and X-ray photographs.
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.
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.
