Question

A sampling tube with a cutting edge is used for extracting the samples. The sampling tube has the following dimensions:
$\text{Inner diameter of cutting edge}=D_c$
$\text{Outer diameter of cutting edge}=D_w$
$\text{Inner diameter of the sampling tube}=D_s$
$\text{Outer diameter of the sampling tube}=D_t$
What is the area ratio $A_r$ of the sampling tube ?

• A. $A_r=\frac{D_w^2-D_c^2}{D_c^2}\times 100\%$
• B. $A_r=\frac{D_t^2-D_c^2}{D_c^2}\times 100\%$
• C. $A_r=\frac{D_t^2-D_w^2}{D_w^2}\times 100\%$
• D. $A_r=\frac{D_t^2-D_s^2}{D_s^2}\times 100\%$

Answer 1

The correct option is A $A_r=\frac{D_w^2-D_c^2}{D_c^2}\times 100\%$

$A_r=\frac{D_w^2-D_c^2}{D_c^2}\times 100\%=Ratioof$ displaced volume of soil to that of the sample collected. Area ratio is the most critical factor that affects sample disturbance. If $A_r<10\%$, the sample disturbance is considered to be small.