7 WEIGHT SOUNDING TEST (WST)
(1)P The weight sounding penetrometer consists of a screw-shaped point, rods, weights or other loading system and a handle or a rotating device. The weight sounding test is made as a static sounding in soft soils when the penetration resistance is less than 1 kN. When the resistance exceeds 1 kN the penetrometer is rotated, manually or mechanically, and the number of halfturns for a given depth of penetration is recorded.
(2) The weight sounding test is primarily used to give a continuous soil profile and an indication of the layer sequence. The penetrability in even stiff clays and dense sands is good.
(3) The weight sounding test may also be used to estimate the density of cohesionless soils and to estimate the undrained shear strength of cohesive soils.
(4)P The tests shall be carried out in accordance with a method that complies with the requirements given in this section.
(5)P The test method used shall be reported in detail with the test results.
(6) The test method may be reported by reference to a standard.
(7)P Any deviation from the requirements given below shall be justified and in particular its influence on the results of the test shall be commented upon.
(1)P weight sounding resistance: either the smallest standard load for which the penetrometer sinks without rotation, or the number of halfturns per 0,2 m of penetration when the penetrometer has its maximum load and is rotated.
(2)P manual weight sounding test: test made by rotating the penetrometer by hand using a handle. The penetrometer is loaded by weightpieces.
(3)P mechanized weight sounding test: test in which rotating of the penetrometer is made mechanically. The penetrometer is loaded mechanically or by dynamometer or by weightpieces.
7.3.1 Penetrometer tip
(1)P The diameter of the circumscribed circle of the screw-shaped point shall be 35 mm. The length of the point shall be 200 mm. The point is twisted one turn to the left over a length of 130 mm and it has a pyramidical tip as shown in figure 7.1.
(2)P The diameter of the circumscribed circle for the worn point shall not be less than 32 mm. Maximum allowable shortening of the point is 15 mm due to wear. The tip of the point shall not be bent or broken.
**) for 22 mm rods
7.3.2 Weights or loading system
(1)P The weight-pieces for manual weight sounding test shall comprise of one 50 N clamp, two 100 N weights and three 250 N weights, total 1000 N.
(2) The weights for mechanized test can be replaced by a dynamometer with the measuring range from 0,05 kN up to 1,00 kN.
(3)P The maximum allowable deviation from the standard loads and the dynamometer scale shall be ±5%.
(1)P The diameter of the rods shall be 22 mm.
(2) The length of one rod should be at least 1 m. For mechanized weight sounding test the length of the rod can be 1,0 to 2,0 m.
(3)P The deviation from the straight axis shall not exceed 4 mm per m for the lowest 5 m of the rods and 8 mm per m for the remainder. The allowable eccentricity of the coupling shall not be more than 0,1 mm. The angular deviation for a joint between two straight rods shall not be more than 0,005 rad.