Indraratna, AS, Balasubramanian, AK & Khan, MJ 1995, 'Effect of fly ash with lime and cement on the behavior of a soft clay', Quarterly Journal of Engineering Geology, vol. 28, no. 2, pp. 131-142.
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Indraratna, B 1995, 'Closure to “Performance of Embankment Stabilized with Vertical Drains on Soft Clay” by B. Indraratna', Journal of Geotechnical Engineering, vol. 121, no. 4, pp. 393-395.
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Indraratna, B, Sullivan, J & Nethery, A 1995, 'Effect of groundwater table on the formation of acid sulphate soils', Mine Water and the Environment, vol. 14, no. 1, pp. 71-83.
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Acid sulphate soils are formed when pyrite within a soil layer is oxidised, generating sulphuric acid. The oxidation of pyrite often results in yellow mottles of jarosite. The pH levels in greatly affected areas are often less than 4.0, and the associated environmental impacts include fish kills, retarded growth of crops and changes in water chemistry. Certain regions of acid sulphate soils along the South Coast of NSW are of much concem, because of limited land available for food production and cash crops. This study quantifies the effect of changes of the groundwater table on the acidity of the coastal flood plain in Berry, located on the Illawarra coastline, New South Wales. Based on several boreholes and drain sites, the existence of jarosite was verified, characterising the study area as a potential acid-sulphate soil region. The field investigation of the study area included the monitoring of groundwater and drain water quality, including the pH and aluminium levels. The study shows convincingly that the increase in groundwater level is effective in preventing adverse pH and aluminium levels. © 1995 Springer-Verlag.
Sheng, D & Axelsson, K 1995, 'Uncoupling of coupled flows in soil—a finite element method', International Journal for Numerical and Analytical Methods in Geomechanics, vol. 19, no. 8, pp. 537-553.
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AbstractCoupled flow of water, chemicals, heat and electrical potential in soil are of significance in a variety of circumstances. The problem is characterized by the coupling between different flows, i.e. a flow of one type driven by gradients of other types, and by the dual nature of certain flows, i.e. combined convection and conduction. Effective numerical solutions to the problem are challenged due to the coupling and the dual nature.In this paper, we first present a general expression that can be used to represent various types of coupled flows in soil. A finite element method is then proposed to solve the generalized coupled flows of convection‐conduction pattern. The unknown vector is first decomposed into two parts, a convective part forming a hyperbolic system and a conductive part forming a parabolic system. At each time step, the hyperbolic system is solved analytically to give an initial solution. To solve the multi‐dimensional hyperbolic system, we assume that a common eigenspace exists for the coefficient matrices, so that the system can be uncoupled by transforming the unknown vector to the common eigenspace. The uncoupled system is solved by the method of characteristics. Using the solution of the hyperbolic system as the initial condition, we then solve the parabolic system by a Galerkin finite element method for space discretization and a finite difference scheme for time stepping.The proposed technique can be used for solving multi‐dimensional, transient, coupled or simultaneous flows of convection‐conduction type. Application to a flow example shows that the technique indeed exhibits optimality in convergence and in stability.
Sheng, D, Axelsson, K & Knutsson, S 1995, 'Frost Heave due to Ice Lens Formation in Freezing Soils', Hydrology Research, vol. 26, no. 2, pp. 125-146.
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A frost heave model which simulates formation of ice lenses is developed for saturated salt-free soils. Quasi-steady state heat and mass flow is considered. Special attention is paid to the transmitted zone, i.e. the frozen fringe. The permeability of the frozen fringe is assumed to vary exponentially as a function of temperature. The rates of water flow in the frozen fringe and in the unfrozen soil are assumed to be constant in space but vary with time. The pore water pressure in the frozen fringe is integrated from the Darcy law. The ice pressure in the frozen fringe is determined by the generalized Clapeyron equation. A new ice lens is assumed to form in the frozen fringe when and where the effective stress approaches zero. The neutral stress is determined as a simple function of the unfrozen water content and porosity. The model is implemented on an personal computer. The simulated heave amounts and heaving rates are compared with experimental data, which shows that the model generally gives reasonable estimation.
Sheng, D, Axelsson, K & Knutsson, S 1995, 'Frost Heave due to Ice Lens Formation in Freezing Soils', Hydrology Research, vol. 26, no. 2, pp. 147-168.
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An operational model for estimation of frost heave in field where stratified soil profile appears is presented. The model is developed from the research model described in part B. Soil layers are first classified into frost-susceptible layers (FSL) or non-frost-susceptible layers (NFSL). In an FSL, both heat flow and water flow are considered and ice lensing can occur. In a NFSL, only heat flow is possible and no ice lensing is allowed. The governing equations for heat and mass transfer are established for the time period when the frost front is moving within FSL. Capillarity and unsaturation are also considered. The operational model is verified by field measurements of heave amounts. Examples of application are given.
Taylor, D 1995, 'Short fatigue crack growth in cast iron described using P−a curves', International Journal of Fatigue, vol. 17, no. 3, pp. 201-206.
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A new approach to the description of short crack growth - the P - a curve - has been tested using extensive data on submillimetre cracks in a grey cast iron. It is shown that this approach, in which the probability of growth is plotted as a function of crack length, is valid in that it produces a plot that is consistent from specimen to specimen and is a function of both crack length and stress level. The growth probability, Pg, can be defined systematically in terms of the average amount of crack growth, Îcmean within a given interval of cycles, ÎN; this leads to the concept that Pg characterizes growth at a particular rate: Îcmean/ÎN. Predictions were made of the endurance, Nf, using a numerical model that simulates the growth of a large number of cracks. Crack coalescence was found to be a critical feature, both of the model and of the experimental findings. The great majority of crack growth was found to occur by coalescence; a simple model of coalescence, based on fracture mechanics, was successfully incorporated into the predictions.
Khalili, N & Khabbaz, MH 1970, 'On the theory of three-dimensional consolidation in unsaturated soils', UNSATURATED SOILS, VOLS 1 AND 2, 1st International Conference on Unsaturated Soils (UNSAT 95), A A BALKEMA, PARIS, FRANCE, pp. 745-750.
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A more complete and unified treatment of the theory of three-dimensional unsaturated consolidation is presented. The governing differential equations based on the equations of equilibrium, the effective stress concept, Darcyâs law, Fickâs law and the conservation of fluid mass are derived.
