SOIL GENESIS AND PROBLEMATIC SOILS PUBLISHED

Gh. ROGOBETE, Adia GROZAV
In the civil engineering, the soils represent a relatively loose material originating from theupper rock layers or from the soil profile itself. There are many soil – forming processes. Soil – formingprocesses vary with time but also with parent materials, topographical relief, vegetation, and climate.Poor soil conditions in terms of engineering increase the cost of construction. Fundamental soilproperties such as cation exchange and shrink – swell properties are all influenced by molecular - scaledifferences in soil clay minerals. The following outlines of soil – forming processes are presented:gleization (develop anaerobic conditions in the upper part), paludization (is an accumulation ofundercayed plant debris), podzolization (are soils characterized by the presence of a spodic horizon),ferrolysis (a hardpan of iron oxide may build up at the interface of the aerobic and anaerobic zones),ferrallitization, biocycling, lessivage is the process of clay accumulation; Lixiviation is a process ofleaching of major cations from soil minerals and their loss from the soil in groundwater; melanisation,andisolization, vertization - is the physical soil overturning and mixing, characteristic of soils rich inswelling clays (smectites), which swell when wet and shrink when dry; anthrosolization - said, about anymodification of properties, due to human activity, including soil modifications that may significantlyinfluence soil development; salinization, solonization, cryoturbation. Quicksands are encountered inexcavations made in fine sands that are below the watertable. Loess is, from this point of view, a typicalcollapsible material. The structural stability of collapsible soils is related to the suffusion process, that isthe process of lateral and vertical removal of the fine soil particles by subsurface flow, often leading tosettling, formation of potholes or piping. Chemical and hydrodynamic suffosion are distinguished. Thesevolume changes can give rise to ground movements that may result in damage to buildings, and also inroad construction. Severe erosion or worse, serious piping damage to embankments and piping failuresof earth dams have occurred when dispersive soils have been used in their construction. Excessivesettlement are the principal problems confronting the engineer working on a peat soil. A number oftechnique can be used to stabilize these soils.
soil forming, civil engineering, quicksands, collapsible, expansive, dispersive
Presentation: oral

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