Question

Why does For order-of-magnitude information, it is practical to use correlations between cone penetration resistance and the standard penetration test?

Need explanation and step by step solution and without plagrism

Answer 1

Ans

A) Relationship between Standard penetration number and static cone penetration test:

For effective use of the cone penetration test, some reliable calibration is required. This consists of comparing the results with those obtained from conventional tests conducted on undisturbed samples in a laboratory. It is also convenient to compare the cone test results with the standard penetration test results. As the standard penetration tests have been more commonly conducted in the past, good correlation studies are available between the SPT number (N) and the Engineering properties of the soil. If the cone penetration results are related to the SPT number N, indirect correlations are obtained between the cone test results and the Engineering properties of soil.

The following relations hold approximately good between the point resistance of the cone (q) and the standard penetration numy (N).

I) Gravels q = 800 N to 1000 N

ii) Sands q = 500 N to 600 N

iii) Silty Sands q = 300 N to 400 N

iv) Silts and Clayey Silts q = 200 N

Where q is in KN/m2

B) Relationship between Standard penetration number and Dynamic cone test:

The dynamic cone resistance Nc is correlated with the SPT number N. The following approximate relations may be used when a 50mm diameter cone is used.

Nc = 1.5 N for depths upto 3m

Nc = 1.75 N for depths between 3 to 6m

Nc. = 2.0 N for depths greater than 6m