M Rouainia
Newcastle University, School of Civil Engineering & Geosciences, Faculty Member
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As part of the upgrade of the Paciflc Highway along the east coast of Australia, a substan- tial length of raised embankment is required to be constructed over areas of soft clay. Fully instrumented trial embankments have been constructed... more
As part of the upgrade of the Paciflc Highway along the east coast of Australia, a substan- tial length of raised embankment is required to be constructed over areas of soft clay. Fully instrumented trial embankments have been constructed on estuarine clay deposits along the proposed alignment to acquire observational data on the settlement and stability of the high- way
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ABSTRACT In this paper, we present a 2D coupled fluid-structure interaction procedure to assess the stability of a cracked gravity dam against increasing water level. In this procedure the structure is assumed to be a discontinuous... more
ABSTRACT In this paper, we present a 2D coupled fluid-structure interaction procedure to assess the stability of a cracked gravity dam against increasing water level. In this procedure the structure is assumed to be a discontinuous deformable solid containing pre-existing cracks. Thus, the Discontinuous Deformation Analysis DDA method is used to study the solid discontinuous medium, and the continuum finite element flow model to calculate the hydrostatic forces corresponding to the water level. The contact constraints between discrete blocks are imposed through an implicit augmented Lagrangian format. Numerical results show the potential of the proposed coupled model to quantify the direct influence of the nature and location of the internal cracks on the overall stability of common gravity dams.
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Climate change has the potential to have a serious detrimental effect on huge parts of our infrastructure. Embankments and cuttings make up a large proportion of this infrastructure. Predicted future climate scenarios in the U.K. show an... more
Climate change has the potential to have a serious detrimental effect on huge parts of our infrastructure. Embankments and cuttings make up a large proportion of this infrastructure. Predicted future climate scenarios in the U.K. show an increase in rainfall during the winter months and a decrease in the summer months, this will affect the annual cyclic pore water pressure changes within a slope, there will be higher pore pressures at the end of winter and lower pore water pressures at the end of summer. Finite element analysis by Kovacevic et al (Kovacevic et al., 2001) show that seasonal cyclic stress changes can cause outward movement, strain softening and eventual collapse. This collapse depends on the severity and number of the shrink/swell cycles. In order to assess the possible impacts of climate change this paper outlines a method for predicting pore pressure changes within a typical railway embankment using both present day and future climatic data within the FLAC tp flow f...
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ABSTRACT An analytical solution for consolidation around spherical cavity contraction is developed. This solution has the potential to evaluate consolidation around tunnel heads. The initial excess pore water pressure immediately after... more
ABSTRACT An analytical solution for consolidation around spherical cavity contraction is developed. This solution has the potential to evaluate consolidation around tunnel heads. The initial excess pore water pressure immediately after the creation of the cavity is estimated from the cavity expansion/contraction theory using a linear-elastic-perfectly-plastic soil model. Expressions for the decay of pore water pressure with time are obtained using elasticity. Curves showing the variation of pore water pressure with time are plotted in nondimensional form. Comparison with two-dimensional coupled stress-pore pressure finite element analysis shows that the proposed semi-analytical solution can successfully predict the poro-elasto-plastic behavior around spherical cavity.
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ABSTRACT This work extends a previously developed methodology for computational plasticity at finite strains that is based on the exponential map and logarithmic stretches to the context of isotropic elasto-viscoplastic solids. A... more
ABSTRACT This work extends a previously developed methodology for computational plasticity at finite strains that is based on the exponential map and logarithmic stretches to the context of isotropic elasto-viscoplastic solids. A particular form of the strain-energy function, given in terms of its principal values is employed. It is noticeable that within the proposed framework, the small strain integration algorithms, and the corresponding consistent tangent operators, automatically extend to the finite strain regime. Central to the effort of this formulation is the derivation of the closed form of a tangent modulus obtained by linearization of incremental non-linear problem. This ensures asymptotically quadratic rates of convergence of the Newton–Raphson procedure in the implicit finite element solution. To illustrate the performance of the presented formulation, several numerical examples, involving failure by strain localization and finite deformations, are given. © 1998 John Wiley & Sons, Ltd.
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ABSTRACT A numerical model based on the method of Discontinuous Deformation Analysis (DDA) is presented to simulate the stability of rubble-mound breakwaters. The breakwater is considered as a stack of rigid blocks moving against each... more
ABSTRACT A numerical model based on the method of Discontinuous Deformation Analysis (DDA) is presented to simulate the stability of rubble-mound breakwaters. The breakwater is considered as a stack of rigid blocks moving against each other and subject to seismic loading. The contact and cohesion between blocks as well as the geometric shape of the blocks are included in this analysis. A numerical simulation, with an analytical study, has been made to estimate the optimum cohesion between blocks necessary to increase strength and stability of the dam.
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Geomechanical effects can be significant in many reservoirs, and can be represented in reservoir simulation by (loose or tight) coupling between the geomechanical and flow simulators. As always, there is a scale issue: cell sizes are... more
Geomechanical effects can be significant in many reservoirs, and can be represented in reservoir simulation by (loose or tight) coupling between the geomechanical and flow simulators. As always, there is a scale issue: cell sizes are controlled by the available computational ...
ABSTRACT As part of a programme of finding new uses for industrial wastes, a trial of PFA (pulverized fuel ash) as a thermal grout for borehole heat exchangers has been tested experimentally. Several mixes of PFA-based grouts were... more
ABSTRACT As part of a programme of finding new uses for industrial wastes, a trial of PFA (pulverized fuel ash) as a thermal grout for borehole heat exchangers has been tested experimentally. Several mixes of PFA-based grouts were developed by blending PFA with different solid materials by weight in different mix proportions with a constant percentage of cement. The materials used in these mixes are: fine sand, coarse sand, ground glass, and fluorspar. The thermal conductivity of seven different groups of grouts has been measured at dry and saturated conditions. A new thermal cell that utilizes the steady state technique developed by Newcastle University was used for these measurements. The results show poor enhancement of thermal conductivity using fine sand or medium ground glass, with maximum value of 1.15 W/m K at saturation. Results obtained using coarse or mixed ground glass gave a maximum value of 1.39 W/m K. The highest thermal conductivity values were achieved using fluorspar or coarse sand where the thermal conductivity reached 2.88 and 2.47 W/m K respectively at 20% of PFA. It was also observed that the combination of fluorspar with coarse ground glass can offer relatively high thermal conductivity at both dry and saturated conditions. Moreover, this combination of materials comprises a practical amount of low-cost material (PFA and ground glass).
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O. Davies ,M. Rouainia ,S. Glendinning ,SJ Birkinshaw. (2008) Assessing the influence of climate change on the progressive failure of a railway embankment. ... JR Standing ,PR Vaughan ,S. Charles-Jones ,BT Mcginnity. (2000) The... more
O. Davies ,M. Rouainia ,S. Glendinning ,SJ Birkinshaw. (2008) Assessing the influence of climate change on the progressive failure of a railway embankment. ... JR Standing ,PR Vaughan ,S. Charles-Jones ,BT Mcginnity. (2000) The instrumentation and observed behaviour of ...
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In the last 50 years, there have been many incidences of failure of gravity quay walls. These failures are often associated with significant deformation of liquefiable soil deposits. Gravity quay wall failures have stimulated great... more
In the last 50 years, there have been many incidences of failure of gravity quay walls. These failures are often associated with significant deformation of liquefiable soil deposits. Gravity quay wall failures have stimulated great progress in the development of deformation-based design methods for geotechnical structures. In this paper, the effective-stress analysis method has been used in conjunction with a