AS 1289.6.4.1:2016 pdf free.Methods of testing soils for engineering purposes Method 6.4.1: Soil strength and consolidation tests—Determination of compressive strength of a soil—Compressive strength of a specimen tested in undrained triaxial compression without measurement of pore water pressure.
4 PREPARATION OF SPECIMENS
Procedures for the preparation of test specimens vary considerably in detail but the aim is to produce specimens of required dimensions while minimizing the disturbance and changes to moisture content. The diameter of the specimen is to be selected having regard to the character of the soil and the maximum size of particles present in the sample.
The minimum diameter shall be at least 5 times the diameter of the largest particle and never less than 38 mm. A diameter of 38 mm is acceptable for homogeneous fine-grained soils, but larger diameters are preferable as these minimize sample disturbance.
The test described is limited to specimens in the form of right cylinders with height to diameter ratio of 2 ±2%.
The preparation of specimens shall be as follows:
(a) Obtain from a sample a subsample of the desired diameter in one of the following ways, as appropriate:
(i) From a thin walled sample tube, extrude a sufficient length to provide a test specimen of the required dimensions.
(ii) From a block sample, trim a soil cylinder of sufficient length to provide a test specimen of the required dimensions.
(b) Place the subsample obtained by Step (i) or Step (ii) in the trimming device and prepare the ends, plane and parallel, to provide a test specimen of the required height.
5 PROCEDURE
The procedure shall be as follows:
(a) Measure and record the length, diameter and mass of the sample to a precision that will enable the bulk density to be calculated to an accuracy of ±1%.
(b) Place the specimen on the base pedestal and put the top cap on top of the specimen. Using the membrane stretcher, place the rubber membrane around the specimen and seal the membrane to the top cap and base pedestal by means of rubber rings.
(c) Assemble the cell with the loading ram initially clear of the top cap of the specimen and place the cell containing the specimen in the loading machine. Admit the operating fluid to the cell and raise the pressure to the desired value.
(d) Adjust the loading machine to bring the loading ram a short distance away from the seat on the top of the specimen. Bring the axial deformation measuring device into contact with the adjustable reference point. Select a rate of axial strain that will give a time-to-failure of about 5 to 10 mm. This will normally be provided by a straining rate in the range of 1 to 2 percent per minute. With the ram moving at the selected test speed, record the reading of the load measuring gauge before it contacts the top cap as zero load. For a machine which measures the load inside the cell, read the load directly.
(e) Adjust the loading machine to bring the loading ram just in contact with the seat on the top cap of the specimen and record the initial reading of the axial deformation gauge.
(f) Commence compression and take a sufficient number of simultaneous readings of the load and deformation measuring gauges to define the stress/strain curve. Continue the test until either the maximum value of the load has passed or an axial strain of 20% has been reached. Unload the specimen and record the final reading of the load measuring gauge. If the difference between the final and initial readings of the load gauge exceeds 5% of the maximum applied axial load, the test shall be discarded unless the cause of the discrepancy can be recognized and allowed for in the calculations.AS 1289.6.4.1 pdf download.