Civil Engineering Reference
In-Depth Information
Table 6.3
Quality classes of soil samples for laboratory testing and sampling
categories to be used (after BS EN 1997-2:2007).
Quality class of
sample
Soil properties:
1
2
3
4
5
Unchanged soil properties
particle size
*
*
*
*
water content
*
*
*
density, density index, permeability
*
*
compressibility, shear strength
*
Properties that can be determined
sequence of layers
*
*
*
*
*
boundaries of strata - broad
*
*
*
*
boundaries of strata - fine
*
*
Atterberg limits, particle density, organic content
*
*
*
*
water content
*
*
*
density, density index, porosity, permeability
*
*
compressibility, shear strength
*
Sampling category according to EN ISO 22475-1
A
B
C
From Table
6.3
it is seen that:
●
Sample quality classes 1 to 5 can be achieved from Category A sampling methods.
●
Sample quality classes 3 to 5 can be achieved from Category B sampling methods.
●
Sample quality class 5 can be achieved from Category C sampling methods.
Guidance on which sampling techniques fall into each category for different ground conditions are given
in EN ISO 22475-1:2006. These are summarised in Table
6.4.
Table 6.4
Sampling categories for different soil types.
Soil type
Sampling method:
Clay
Silt
Sand
Gravel Organic
Rotary core drilling
Single-tube
B
C
C
C
B
Double- or triple-tube
A
B
B
-
-
Augering
C(B)
C
C
C
C(B)
Hollow stem augering
B
B
B
B
B
Thin-walled open tube samplers
Pushed
A
A
A
-
A
Percussion
B(A)
-
-
-
-
Thick-walled open tube samplers
Percussion
B(A)
B(A)
B
B
-
Piston samplers
-
A
A
-
-
-
-
-
A
Pushed
Large samplers
A
A
-
-
-
Sampling from trial pit
A
A
A
A
A
Sampling from borehole bottom
A
-
-
-
-
Key: B(A), C(B) - the category in brackets is only achievable in favourable conditions, else the first category applies.
