Question

The observed standard penetration test value in a deposit of fully submerged sand was 45 at a depth of 6 m. The average submerged unit weight of the soil is 9.7 kN/m3. The corrected N value is : (consider only overburden correction) (a) 43.76 (b) 67.14 (c) 54.63 (d) 58.95

Answer 1

Answer:

43.54

Explanation:

Effective overburden pressure  will be $6m\times 9.7=58.2 kN/m^{2}$

Overburden correction is given by

$C_N= \sqrt{\frac {95.76}{p_o}}$

Where and are effective overburden pressure and overburden correction

Substituting the value of overburden pressure then

$C_N= \sqrt{\frac {95.76}{58.2}}= 1.282716\approx 1.28$

Taking hammer efficiency of 0.8,  drill rod length correction factor of 0.9 and  borehole correction factor of 1.05 then corrected SPT value will be

$45*1.28*0.8*0.9*1.05\approx 43.54$