Question5 t is \"Teactive\" clay and why (3 mark) (b) Estimate the ground heave

Question

Question5 t is "Teactive" clay and why (3 mark) (b) Estimate the ground heave (in mm) as indicated in the figure below as the moisture content (on dry mass basis) of the saturated reactive clay layer changed from a moisture content of 15% to 18%. In your calculation, you can assume a one-dimensional expansion in the vertical direction only as horizontal expansions were restrained by the extensive clay deposit in the horizontal directions Prior to rainfall season: moisture content of clay layer 15% 1.2m Saturated reactive clay =2200 kg/m3 Stable Soil After rainfall season: moisture content of clay layer increased to 18% Ground heave 1.2m

Explanation / Answer

a)

A collection of rock-forming, hydrous aluminum silicate minerals to are platy in arrangement and can form by the change of silicate minerals similar to feldsparand amphibole.

Ordinary examples

comprise chlorite, illite, kaolinite, montmorillonite and smectite. a number of clays, such as montmorillonite, have the leaning to enlarge when showing to water, create a likely drill exposure when clay-bearing rock formation are showing to water-base fluids through drilling, perhaps plummeting the permeability of a fine reservoir rock.

Some clays are worn in drilling fluids to figure an impermeable mudcake to cut off a formation as of the invasion of drilling fluid. The structural difference among clays (smectite, kaolinite, chlorite, illite) determines the outside area uncovered to reservoir fluids or inspiring fluids.

usually, higher surface region indicate senior reactivity. though, not all the clay there in a rock is reactive. Clays can be establish in pore spaces, as part of the matrix or as grain-cementingmaterial. Authigenic clays, which grow in the pore from minerals in the connate water, can be pore-filling or pore-lining.

These clays have substantial surface area bare in the pore and can be reactive, while detrital clays that are part of the matrix are typically fewer reactive. Additionally, clays as cementing, or grain-binding, resources may react with water or acid to disaggregate the configuration if they are not sheltered by quartz overgrowths.

The most ordinary clays that make clay trouble are kaolinite, smectite, illite and chlorite. These minerals can be treat with hydrofluoric acid [HF].

b) ground heave = saturated reactive clay* thickness of bed/ increased moisture content

= 2200*1.2/18

=146.6

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