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11.
Kolleen?Carlson Farid?SariosseiriEmail author Balasingam?Muhunthan 《Geotechnical and Geological Engineering》2011,29(5):837-844
The Portland cement manufacturing process produces considerable amount of cement kiln dust (CKD). While many facilities are
able to reuse a significant portion of CKD in their production lines, a large percentage is removed as industrial waste and
placed in landfills. Because of the large amount of material potentially available for use, and in an effort to cut disposal
costs, alternative and beneficial uses for CKD need to be investigated. This study presents experimental results of the use
of CKD in modification and stabilization of soils from the Aberdeen and Everett areas in the state of Washington. These soils
are typically wet of the optimum water content and pose problems during geotechnical construction. CKD was added in percentages
of 5, 10, 15, and 20% by dry weight of the soils. Laboratory tests, including drying rate of the soils, Atterberg limits,
standard proctor and unconfined compressive strength were conducted. Results of the investigation showed significant improvement
in drying rate and unconfined compressive strength of the CKD treated specimens as the percentage of CKD increased. It was
also found that lower percentages of CKD can be used for modification purposes, whereas higher percentages of CKD can be used
for both modification and stabilization purposes in geotechnical construction. 相似文献
12.
Many experiments on conical piles of granular materials have indicated, contrary to simple intuition that the maximum vertical stress does not occur directly beneath the sand‐pile vertex but rather at some distance from the apex resulting in a ring of maximum vertical stress. Some recent experiments have shown that the observed stress dip is very much dependent on construction history. A multi‐slip model has been proposed to investigate the stress dip phenomenon in granular heaps. The double‐slip version of the model was implemented into ABAQUS and used to study the vertical stress distribution along the base of a granular pile. The numerical simulations show that plastic deformation is confined within the localized region around the apex while the rest of the pile is in an elastic state of deformation. Within the plastic region the stress distribution differs significantly depending on the initial active slip orientation. The results show that for homogenous state of granular materials such as those produced by a raining procedure the vertical stress profile along the base reached its peak at the apex (i.e. no dip was observed). On the contrary, granular heaps constructed by the use of a localized source such as a funnel resulted in a significant reduction in the stress distribution within the ring with the minimum attained beneath the peak (i.e. a dip). Therefore, we believe that the initial microstructure and thus the initial slip orientation resulting from sand deposition is the source of the stress dip phenomenon. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
13.
A consistent methodology based on the critical state framework to characterize the different regimes of fine-grained soil behavior under earthquake loads is put forward. Shear strength and deformation behavior of soils depend in a major way on the combination of volume and confining stress. Depending on their combination, a soil aggregate may fracture into clastic debris, fail with fault planes, or yield plastically. This characterization of the class of limiting soil behavior is used to analyze the potential for large deformation and liquefaction in fine grained soils. The central piece of the proposed characterization is the (η, LI5) stability diagram where η = q/p′ and LI5 = LI + 0.5 log (p′/5). This diagram captures the effects of soil plasticity through liquidity index LI, confinement through mean normal effective stress p′, and shear stress q through the stress ratio η. The three regions of behavior; fracture, fault, and fold/yield are identified. Soils become susceptible to liquefaction when they shift into the fracture zone (LI5 ≤ 0.4), or if they plot outside of the stable yielding region.Under earthquake loading, the initial soil states will migrate into different regions in the stability diagram depending on their initial location, shear stress increment, and, pore pressure response. The final position of the soil state would dictate the type of limiting behavior expected in the field; fracture, rupture or yield. The final states which fall into the fracture region have the potential for catastrophic failures including “liquefaction”; the ones which fall onto the rupture region would experience the attainment of a peak stress ratio followed by softening along failure planes; the ones in the yield region would continue to yield in a stable manner. The latter two types of deformations while resulting in large deformation may not be of a catastrophic nature. The proposed characterization is used to examine the liquefaction susceptibility of fine grained soils from China, Taiwan, and Turkey. Use of simplified empirical criteria based on parameters such as plasticity index and fines contents may not capture the true nature of the type of undrained limiting behavior of fine grains soils in the field including liquefaction. 相似文献
14.
In the past decade Australian immigration policy has emphasised settlement of refugees/humanitarian entrants in rural and regional locations, in preference to metropolitan areas. The settlement outcomes of a case study of African humanitarian entrants of South Sudanese background in Murray Bridge, a regional centre in South Australia, are examined. These participants were self-settled secondary movers from metropolitan Adelaide. The factors which attracted them were centred on employment. Settlement outcomes for Murray Bridge respondents were better than their urban counterparts, in terms of both housing and employment outcomes. However, some later left Murray Bridge because of a lack of opportunities for tertiary education. The results highlight issues of sustainability of settlement and retention, in regional centres in Australia, and of the fluidity of attraction and retention factors and therefore settlement in regional centres. 相似文献
15.
A program for the simulation of two‐dimensional (2‐D) fluid flow at the microstructural level of a saturated anisotropic granular medium is presented. The program provides a numerical solution to the complete set of Navier–Stokes equations without a priori assumptions on the viscous or convection components. This is especially suited for the simulation of the flow of fluids with different density and viscosity values and for a wide range of granular material porosity. The analytical solution for fluid flow in a simple microstructure of porous medium is used to verify the computer program. Subsequently, the flow field is computed within microscopic images of granular material that differ in porosity, particle size and particle shape. The computed flow fields are shown to follow certain paths depending on air void size and connectivity. The permeability tensor coefficients are derived from the flow fields, and their values are shown to compare well with laboratory experimental data on glass beads, Ottawa sand and silica sands. The directional distribution of permeability is expressed in a functional form and its anisotropy is quantified. Permeability anisotropy is found to be more pronounced in the silica sand medium that consists of elongated particles. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献