A layer of normally consolidated, saturated silty clay of

A layer of normally consolidated, saturated silty clay of 1 m thickness is subjected to one dimensional consolidation under a pressure increment of 20 kPa. The properties of the soil are: specific gravity = 2.7, natural moisture content = 45%, compression index = 0.45, and recompression index = 0.05. The initial average effective stress within the layer is 100 kPa. Assuming Terzaghi’s theory to be applicable, the primary consolidation settlement (rounded off to the nearest mm) is

G = 2.7, w = 45% = 0.45, H = 1 m
S_r = 1 (standard)
C_c = 0.45, C_r = 0.05, σ₀ = 100 kPa ∆σ = 20 kPa.

e₀ =	wG	=	.45 × 2.7	= 1.215
	S_r		1

Consolidation settlement, Sf or ∆H

= H.	C_c	log₁₀		σ_f
	1 + e₀			σ₀

= H.	C_c	log₁₀		σ₀ + ∆σ
	1 + e₀			σ₀

= 1 ×		.45		× log₁₀		100 + 20
		1 + 1.215				100

= .016 m = 16 mm