Annex J

(Informative)

Flat dilatometer test (DMT)

(1) This Annex gives an example of correlations between E_oed and DMT results. These correlations may be used to determine the value of the one-dimensional tangent modulus (E_oed = dσ/dε) from results of DMT tests, through:

E_oed = R_M×E_DMT

in which R_M is estimated either on the basis of local experience or using the following relationships:

if I_DMT ≤ 0,6; then R_M = 0,14 + 2,36 lgK_DMT

if 0,6 < I_DMT < 3,0; then R_M = R_M0 + (2,5 – R_M0)lg K_DMT, in which

R_M0 = 0,14 + 0,15(I_DMT – 0,6);

if I_DMT ≥ 3; then R_M = 0,5 + 2lgK_DMT

if K_DMT > 10; then R_M = 0,32 +2,18 lg K_DMT

if values of R_M < 0,85 are obtained in the above relationships, R_M is taken to be equal to 0,85.

where

NOTE This example was published by Marchetti (2001), For additional information and design examples, see X.3.7.

Annex K

(informative)

Plate loading test (PLT)

K.1 Example of deriving the value of undrained shear strength

(1) This is an example of deriving the undrained shear strength (c_u), which can be obtained using the following equation:

where

NOTE This example was published by Marsland (1972). For additional information and examples, see X.3.8.

K.2 Example of deriving the value of the plate settlement modulus

(1) This is an example of deriving the plate settlement modulus E_PLT (secant modulus).

(2) For loading tests made at ground level or in an excavation where the bottom width/diameter is at least five times the plate diameter, the plate settlement modulus (E_PLT) may be calculated from the general equation:

where

(3) If not determined in other ways, v is equal to 0,5 for undrained conditions in fine soil and 0,3 for coarse soil.

(4) If the test is made at the base of a borehole, the value of E_PLT may be calculated from the equation:

where

Figure K.1 – Depth correction factor C_z as a function of plate diameter b and depth z for PLT results obtained with a uniform circular load at the base of an unlined shaft

NOTE This example was published by Burland (1969). For additional information and examples, sec X.3.8.

K.3 Example of deriving the value of coefficient of sub-grade reaction

(1) This is an example of deriving the coefficient of sub-grade reaction (k_s) which may be calculated from the equation:

where

(2) The dimensions of the loading plate should be stated, when calculating values of k_s.

NOTE This example was published by Bergdahl (1993). For additional information see X.3.8.

K.4 Example of a method to calculate the settlement of spread foundations in sand

(1) This is an example of deriving settlements directly. The settlements of a footing in sand may be derived empirically according to the relations given in Figure K.3, if the ground beneath the footing to a depth larger than two times the width is the same as the ground beneath the plate (see Figure K.2).

Key

• 1 test plate
• 2 footing
• 3 influenced zones

Key

• 1 loose
• 2 medium dense
• 3 dense

NOTE This example was published by Bergdahl el al (1993). For additional information and examples, see X.3.8.