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Seepage Control on Dams with Sand/Gravel Filters Recent Industry Advances Michele Lemieux, P.E. Montana Dam Safety Program فایل پی دی اف در 40 اسلاید منبع Lemieux_MADCS_filter_drainv2 (2).pdf

Heave Behavior of Granular Pile Anchor-Foundation (GPA-Foundation) System in Expansive Soil Original Article, D33 Ibrahim S.F., Aljorany A.N. and Aladly A.I. J. Civil Eng. Urban. 4(3): 213-222. 2014 ABSTRACT: Granular Pile Anchor (GPA) is one of the innovative foundation techniques, devised for mitigating heave of footing resulting from the expansive soils. This research attempts to study the heave behavior of (GPA-Foundation System) in expansive soil. Laboratory tests have been conducted on an experimental model in addition to a series of numerical modelling and analysis using the finite element package PLAXIS software. The effects of different parameters, such as (GPA)length (L) and diameter (D), footing diameter (Df), expansive clay layer thickness (H) and presence of non-expansive clay are studied. The results proved the efficiency of GPA in reducing the heave of expansive soil and showed that the heave can be reduced with increasing length and diameter of GPA. The heave of (GPA-Foundation System) is controlled by three independent variables these are (L/D) ratio, (L/H) ratio and (Df/D) ratio. The heave can be reduced by up to (38 %) when (GPA) is embedded in expansive soil layer at (L/H=1) and reduced by about (90 %) when GPA is embedded in expansive soil and extended to non-expansive clay (stable zone) at (L/H=2) at the same diameter of GPA and footing. An equation (mathematical mode1) was obtained by using the computer package (SPSS 17.0) for statistical analysis based on the results of finite element analysis relating the maximum heave of (GPA-Foundation System) as a function of the above mentioned three independent variables with coefficient of regression of (R2 = 92.3 %). Keywords: Expansive Soil; Sand; Heave; Granular Pile Anchor (GPA); Foundation; PLAXIS; Finite Element. منبع: [Hidden Content] دانلود: [Hidden Content].,%204%20(3)%20213-222,%202014.pdf J. Civil Eng. Urban., 4 (3) 213-222, 2014.pdf

Cost Implication of Mitigating the Effect of Clay/Silt Content of Sand on Concrete Compressive Strength Oiginal Article, B25 Olanitori LM. J. Civil Eng. Urban. 2(4): 143-148. 2012. ABSTRACT: In Nigeria, reinforced concrete is one of the major building materials been used in the construction of buildings. In the specification of concrete, prescribed mix is normally used. However, tests carried out on different batches of concrete produced, using prescribed mix 1:2:4 of concrete show that the concrete did not acquire the 20N/mm2 expected strength at the age of 28 days. Depending on the type of sand used for the production of the concrete, the acquired strength after 28 days is between 25% and 60% of the expected strength. This reduction in strength will ultimately affect the functionality and durability of structure constructed from such concrete. To mitigate the effect of clay/silt content of sand, the sand can be washed free of clay/silt or the cement is increased in proportion to the percentage content of clay/silt in the sand. Since the mitigation of the clay/silt content of sand on concrete strength comes with extra cost, there is need to determine this cost in other to be able to build effective and safe structures. The author evaluates the cost implication of mitigating this reduction effect of the type of sand used on concrete strength. The extra cost incurred in the production of 1m3 of concrete (using mix ratio 1:2:4) in terms of washing the sand free of clay/silt is 22.5%, while that of cement increment is between 2.22% and 27.75% depending on the percentage of clay/silt content of sand. Mathematical models, which can be used to estimate the cost implication of this mitigation, are derived. Keywords:Reinforcement, Concrete, Sand, Silt, Strength منبع: [Hidden Content] دانلود: [Hidden Content],%20B25.pdf JCEU, B25.pdf

The Influence of Biofilm on the Mechanical Behavior of Sand S. W. Perkins,1 P. Gyr,2 and G. James3 REFERENCE: Perkins, S. W., Gyr, P., and James, G., “The Influence of Biofilm on the Mechanical Behavior of Sand,” Geotechnical Testing Journal, GTJODJ, Vol. 23, No. 3, September 2000, pp. 300–312. ABSTRACT: The growth of microbes on the surface of an object results in the formation of a biofilm, which in sand can lead to a reduction of hydraulic conductivity and can be used for groundwater containment and remediation. Sample preparation and testing techniques for triaxial and oedometer experiments were devised for the purpose of examining the influence of biofilm on the stress-straintime properties of Ottawa sand. Results have shown that biofilm has a negligible influence on the strength and stiffness of the sand but increases time-dependent creep deformation. An elasto-viscoplastic constitutive model was calibrated for biofilm and non-biofilm sand and implemented into a finite-element code for the purpose of predicting creep deformation of a slope and a foundation resting on level ground. Numerical simulations showed that additional creep behavior of the biofilm sand had a negligible influence on the behavior of these geotechnical engineering facilities. KEYWORDS: microbial bacteria, biofilm, biobarrier, sand, triaxial testing, oedometer testing, mechanical behavior, creep, constitutive modeling, finite-element modeling GTJ11052J.6514.pdf