AS 1289.6.4.2:2016 Methods of testing soils for engineering purposes
8 CONSOLIDATION
If the effective consolidation stress for the shearing stage has not been achieved during saturation, a consolidation stage shall be conducted. The procedure for the consolidation shall be as follows:
(a) After back pressure saturation the specified test effective stress shall be reached through increasing the cell pressure while maintaining a constant back pressure. A number of consolidation stages may be required as the effective stress change shall not be more than 2.5 times the preceding value. Sufficient time shall be allowed to complete consolidation for each stage.
(b) The specimen shall be allowed to consolidate by drainage through the porous discs at both ends of the specimen. Drainage from only one end is acceptable if pore pressure is being measured at the other end to indicate the progress of consolidation. However,
this procedure will increase the time for the consolidation stage.
(c) Readings of volume change with time shall be taken at regular intervals and consolidation shall continue until primary consolidation is complete.
(d) Determine the c v following the procedures set out in Appendix A.
10 SHEARING
The procedure for shearing shall be as follows:
(a) Adjust the loading machine straining rate to that required by previous calculation in Clause 9. Check that the cell and back pressures required to give the specified effective stress for the test are applied.
(b) Ensure all drainage taps from the specimen are closed, allowing only for pore pressure measurement.
(c) Record the initial load, pore pressure and displacement readings then commence straining. Take a sufficient number of simultaneous readings to define the stress/strain curve. It is recommended that as a minimum, readings be taken at intervals of 0.2% axial strain until a strain of 4% and at intervals of 0.5% thereafter.
(d) Continue the test until the axial strain reaches 20%.
(e) Reduce the cell pressure to zero, extract the specimen, and take a photograph to record the mode of failure. Examine and record the nature of layers, stones,calcareous matter and other physical features.
(f) Determine the moisture content of the whole specimen in accordance with AS 1289.2.1.1.