Which sequence of states is correct as water content increases?

Solid, semi-solid, plastic, liquid

Liquid, plastic, semi-solid, solid

Semi-solid, solid, plastic, liquid

Plastic, solid, liquid, semi-solid

The solid-state stress-strain curve shows:

High strength, brittle with sharp peak and drop, small failure strain

In the plastic state (wp < w < wl):

It can be moulded without cracking; curve rises gradually and levels off

The soil is brittle and crumbles

Volume decreases on drying with high strength

Stress is independent of strain

As water content increases, peak strength and failure strain:

Strength drops and failure strain increases

Strength rises and strain drops

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Stress-strain curves, consistency states

Short answer

The stress-strain curve for solid soil shows a high peak strength with brittle failure; semi-solid is stiff and brittle; plastic soil yields and strain hardens with lower strength; liquid soil flows at almost zero strength, the stress-strain curve lying on the strain axis. As water content rises, peak strength falls and failure strain increases.

Draw the stress-strain curves (graph) for soil at different consistency states.

Soil changes its state with water content: solid, semi-solid, plastic and liquid, separated by the shrinkage limit ( $w_s$ ), plastic limit ( $w_p$ ) and liquid limit ( $w_l$ ). The stress-strain behaviour differs in each state.

Stress-strain curves

 Stress
  |      ___ Solid (brittle, peak
  |    /\     then sudden drop)
  |   /  \______ Semi-solid
  |  /    ______ Plastic (yields,
  | /  __/       strain hardens
  |/ _/ ......... Liquid (no
  |/.-'           stress, flows)
  +-------------------- Strain

State	Water content	Behaviour
Solid	$w < w_s$	Very high strength, brittle, small strain at failure, no volume change on drying
Semi-solid	$w_s < w < w_p$	Stiff, brittle, crumbles when moulded, volume decreases when dried
Plastic	$w_p < w < w_l$	Can be moulded without cracking; strength falls and strain at failure rises; ductile (plastic flow)
Liquid	$w > w_l$	Flows like a viscous fluid; almost zero shear strength; stress is nearly independent of strain

As water content rises, the peak strength drops and the strain at failure increases. The brittle curve has a sharp peak with a post-peak drop, the plastic curve rises gradually and levels off, and the liquid curve lies on the strain axis.

✓ Answer checked by Claude Opus 5.5 (high effort)

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