AS 1289.6.2.2:2020 pdf free download.Methods of testing soils for engineering purposes Method 6.2.2: Soil strength and consolidation tests – Determination of shear strength of a soil一Direct shear test using a shear box.
7 Procedures
7.1 Shearing of specimen in one direction
7.1.1 General
Shearing of the specimen in one direction is used to determine the peak and ultimate strengths.
7.1.2 Procedure
The procedure shall be as follows:
(a) After consolidation Is complete, remove the locating pins.
(b) For shear boxes in the range of 50 mm to 100 mm, separate the two box halves by between 0.0 mm and 0.5 mm. For 300 mm shear boxes, separate the two box halves between
0.0 mm and 2.0 mm.
NOTE 1 The gap prevents the normal load being transferred from the loading cap to the bottom half of the box. Provided the loading cap and top plates (if used) do not jam in the upper half of the box, any load transfer should be small. The gap should be as small as practicable to prevent extrusion of soil. It is important not to restrain the top half of the box from vertical movement as this can significantly influence the measured shear force.
(c) Calculate the rate of shearing using Equation 6.5.
(d) Commence the test and at regular intervals of shear displacement, record the reading of the proving ring gauge, or load cell and the vertical movement gauge or LDVT. Initially, record readings at least every 0.1 % of the shear plane length, but the frequency of readings can be reduced as shearing progresses.
NOTE 2 Readings should be frequent enough to clearly define the prepeak and post peak behaviours.
(e) Take readings until the limit of travel of the shear box is reached.
7.2 Shearing of specimen with repeated reversal of shear direction
7.2.1 General
Shearing of clay soil specimens to large shear displacements greater than those from shearing in one direction shall be used to determine ultimate or residual shear strengths. The sample shall be sheared in the forward direction. The direction of shear shall then be reversed until the shear box is back at the starting point, and the sample sheared forward again. This is repeated until the shear strength of the clay reaches its ultimate or residual value.
7.2.2 Procedure
The procedure shall be as follows:
(a) Prepare and consolidate clay soil specimens as specified in Clause 6.
(b) After consolidation is complete, switch on the motor and take readings as specified in Step (e’. Calculate the rate of shearing from Equation 65. Shearing shall be slow enough to ensure that excess pore pressures dissipate during shearing.AS 1289.6.2.2 pdf download.
AS 1289.6.2.2:2020 pdf free download
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