It is well known that organic matter may affect the cementing process in soils, but what happens when cement is added to an organic soil? Both the organic matter content and the nature of this organic matter affect the properties of a treated soil. It appears that some organic compounds delay or even inhibit the hydration process of cement, while others do not affect the reaction at all. This paper presents some results of a laboratory study in which 13 different organic compounds were added separately to two different soils, and then treated with 10% cement. To assess the cementing process, undrained shear strength was measured on the different specimens, and some chemical analyses were performed on the pore liquid. The results indicate that the organic acids producing a pH lower than 9 in the pore solution strongly affect the development of cementing products and almost no strength gain was noted. Also, oils and hydrocarbons, which are insoluble in water, delay the cement hydration but do not affect the final strength. Finally, the pH value and the SO4 concentration in the pore solution are good indicators of the cementing effectiveness of the treated specimens.Key words: soil stabilization, organic compounds, undrained shear strength, cement, chemical analyses.
The method of soil stabilization is well known and has been used throughout the world for many decades to improve some soil properties. Although many researchers have studied the effect of adding a cementing agent to a soil, not many of these researchers have explored the effect of treatment on the resulting properties of high water content soils like dredged material. Also, there has been little work concerning the prediction of the mechanical changes to the soil. Therefore, this paper summarizes the results of a research project conducted to define the general mechanical behavior of high water content clayey soils from eastern Canada treated with lime or cement, in terms of compressibility. In the light of this research, the general compressibility behavior has been obtained, defined by relationships between initial void ratio, additive content, and vertical yield stress for a given inorganic or organic soil. These relationships have been normalized on the basis of the one-dimensional compression curve of the remolded and reconstituted untreated soil to give a simple method for predicting the vertical yield stress of a treated soil for any initial void ratio and its resistance to compression.Key words: stabilization, compressibility, yield stress, clayey soils, lime, cement.
The upper section of the Saguenay Fjord was impacted by a catastrophic flood in July 1996. Contaminated sediments were capped by a layer of clean silty post-glacial sediments with background levels of trace metals and polycyclic aromatic hydrocarbons (PAHs). The capping layer was characterized by geotechnical and geochemical methods and its biological recolonization was monitored by annual sampling of the macrofauna. The strong dominance of surface deposit feeders Cirratulidae and Ampharetidae was observed at most stations in the first 2–3 years followed by carnivorous annelids such as Lumbrineridae and Nephtidae species indicating a well recolonized benthic habitat in the Baie des Ha!Ha!. The presence of benthic fauna was a major factor in modifying the density of sediments by physical mixing and irrigation, and in changing the surface roughness. The slope stability of the capping layer is considered as very good except in limited deltaic sectors at the head of the Baie des Ha!Ha! The new layer showed a good efficiency to isolate contaminated sediments from the sediment/water interface. Although manganese and iron were remobilized as the new layer became anoxic, mercury, arsenic and PAHs showed a very limited mobility through the flood layer which allowed geochemists to calculate the present fluxes of toxicants to the Baie des Ha!Ha! without interferences from older contaminated sediments trapped below the flood layer. The present flux of PAHs to bay (0.9 ng.cm-2.g-1) is about 300 times lower than the 1974 flux and 8 times lower than the 1986 flux.
A variety of paradigms shape water resources management, reflecting the evolution of government policies and transient societal values. Integrated Water Resources Management (IWRM) became a predominant management framework in the 1990s whereas the Human Rights-Based Approach (HRBA) to development emerged recently as an influential approach in the water sector. While IWRM and the HRBA overlap significantly, the interactions between these two remain largely unexplored, and their repercussions may be significant. Because IWRM and the HRBA do not share identical premises and objectives, concurrent implementation of the two might also lead to tensions detrimental to water resources management. The purpose of this article is to explore the interactions between IWRM and the HRBA to development in the water sector. Questions raised by perceived conflicts are identified to help address potential tensions when the two approaches coexist. Synergies between IWRM and the HRBA are also detailed to establish how the two approaches are aligned."Most Covenant rights are, at base, claims to scarce resources, and decisions regarding their recognition and enforcement will necessarily involve questions of resource allocation." 1
Explainability is the process of linking part of the inputs given to a calculation to its output, in such a way that the selected inputs somehow “cause” the result. We establish the formal foundations of a notion of explainability for arbitrary abstract functions manipulating nested data structures. We then establish explanation relationships for a set of elementary functions, and for compositions thereof. A fully functional implementation of these concepts is finally presented and experimentally evaluated.
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