Soil Exploration - Notes | Study Civil Engineering SSC JE (Technical) - Civil Engineering (CE)

Chapter 16 
Soil Exploration

SOIL SAMPLE AND SAMPLERS
The soil samples can be of two types: disturbed and undisturbed. A disturbed sample is that in which the natural structure of sols get partly or fully modified and destroyed, although with suitable precautions the natural water content may be preserved. Such a sample should, however, be representative of the natural soil by maintaining the original  proportional of the various soil particles intact.
An undisturbed sample is that in which the natural structure and properties remain preserved.

(i) Inside Clearance

1<C_i<3

(ii) Outside Clearance

1<C_o<2

(iii) Area Ratio (A_r)

A_r < 20% for stiff formation,
A_r < 10% for soft clays

(iv) Recovery Ratio (L_r)

L_r =1  Good recovery
L_r <1 Compressed
L_r <1  Swelled
where,
D₃ = Inner dia of sampling tube
D₄ = Outer dia of sampling tube
D₁ = Inner dia of cutting tube
D₂ = Outer dia of cutting tube