Weight sounding test (WST)
(1) This Annex gives an example of values of the effective angle of shearing resistance (φ') and drained Young's modulus of elasticity (E'), estimated from weight sounding resistance based on Swedish experience. This example correlates the mean value of weight sounding resistance in a layer to the mean values of φ' and E'. (see Table H.1)
|Density index||Weight sounding resistance a,
half-turns /0,2 m
|Effective angle of shearing resistanceb,
|Drained Young's modulusc, (E')
|a Before determination of the relative density, the weight sounding resistance in silty soil should be divided by a factor of 1,3.
b Values given are valid for sands. For silty soil, a reduction of 3 ° should be made. For gravels, 2 ° may be added.
c E' is an approximation to the stress and time-dependent secant modulus. Values given for the drained modulus correspond to settlements after 10 years. They are obtained assuming that the vertical stress distribution follows the 2:1 approximation. Furthermore, some investigations indicate that these values can be 50 % lower in silty soil and 50 % higher in gravelly soil. In over-consolidated coarse soil, the modulus can be considerably higher. When calculating settlements for ground pressure greater than 2/3 of the design pressure in ultimate limit state, the modulus should be set to half the values given in this table.
(2) If only results of weight sounding tests are available, the lower value in each interval for the angle of shearing resistance and Young's modulus in Table H.1 should be selected.
(3) When evaluating weight sounding resistance diagrams for application in Table H.1, peak values caused for example by stones or pebbles should not be accounted for. Such peak values are common in weight sounding tests in gravel.
NOTE This example was published by Bergdahl et al. (1993). For additional information and examples, see X.3.5.