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Question 9.5: For the corrected values of N given in Ex 9.4, determine the...

For the corrected values of N given in Ex 9.4, determine the unconfined compressive strength q_{u} in a clay deposit.

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(a) From Table 9.4

 

\left.\begin{matrix}For N_{60}=42\\ For N_{70}=36\end{matrix}\right\} q_{u}>400 kPa – The soil is of a hard consistency.

 

(b) Per Eq (9.9)

 

q_{u}=\bar{k} N_{c o r} kPa (9.9)

 

q_{u}=\overline{ k } N_{c o r}, \text { where } \overline{ k }=12 (Bowles, 1996)

 

For N_{60}=42, q_{u}=12 \times 42=504 kPa

 

For N_{70}=36, q_{u}=12 \times 36=432 kPa

 

Table 9.4 Relation Between N_{\text {cor }} \text { and } q_{u}
Consistency N_{\text {cor }} q_{u}, kPa
Very soft 0-2 <25
Soft 2-4 25-50
Medium 4-8 50-100
Stiff 8-15 100-200
Very Stiff 15-30 200-400
Hard >30 >400

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