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4.7.2 Objectives

The objectives of each test are given in §4.x.1 of EN 1997-2 (where the x can be determined from the table above). For example, the objectives of CPTs and CPTUs are stated as:

to determine the resistance of soils and soft rock to the penetration of a cone and the local friction on a sleeve

4.7.3 Specific requirements

The specific requirements of each test are given in §4.x.2 of EN 1997-2 by reference to the appropriate part of EN ISO 22476 (see table above).

4.7.4 Evaluation of tests results

The way in which the results of each test should be evaluated is specified in §4.x.3 of EN 1997-2 by reference to the appropriate part of EN ISO 22476 (see table above).

4.7.5 Obtaining derived values from the test results

EN 1997-2 provides a number of example methods that can be used to obtain derived values from the field tests covered.

Annex F provides methods for deriving density index ID from SPT blow count N60 using the following formula:

where o'v0 = the initial vertical effective stress in the ground and 'a' and 'b' are dimension-less constants. The Annex gives values of ID related to N60 for normally consolidated sands but does not provide guidance on relevant values for a or b. It also provides correlations between ID and angle of shearing resistance for silica sands.

Methods are given in Annex D for the derivation of the angle of shearing resistance ^'and drained Young's modulus E' from cone resistance qc, as measured in CPT, CPTM, and CPTU tests. Two methods are provided: one is in the form of a table giving values of ^'and E' for different ranges of qc (for quartz and feldspar sands, silty soils, and gravels); the other is the equation below (for poorly graded sands situated above the water table):

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