AS 12188.8.131.52 pdf download.Methods of testing soils for engineering purposes
This Method describes a procedure for determining the rate and magnitude of consolidation of soil when it is restrained laterally and loaded and drained axially, using either manual loading or automated equipment. The Method gives the most reliable results when used on saturated clay soils, which the consolidation theory applies. NOTE The result of any test reached in accordance with this procedure requires interpretation in relation to the nature of the soil and the way in which the specimen was obtained and prepared.
The following apparatus shall be used: (a) Load device — suitable for applying vertical loads to the specimen. The device shall be capable of maintaining specified loads for long periods of time with an accuracy of ± 2 % of the applied load, and permit application of a given load increment within a period of 10 s without impact. In any increment, if the time to apply the load exceeds 10 s the time it took shall be reported. NOTE 1 Some automated devices may require adjustment of the rate of load application to ensure the load increment is applied within the 10 s limit. (b) Consolidation cell — a device to hold the specimen in a ring which is either fixed (to the base of the consolidation cell) or floating (supported by friction on the periphery of the specimen) with porous plates on each face of the specimen. The consolidation cell shall also provide means for inundating the specimen with water, for transmitting the vertical load, and for measuring the change in thickness of the specimen. The consolidation ring shall meet the following requirements: (i) The ring shall be metallic with a cutting edge to aid in specimen preparation having a minimum wall thickness of 3 mm and be corrosion resistant in relation to the soil to be tested. The inner surface of the ring shall be smooth. NOTE 2 Suitable grease — Silicone or “PTFE” (Polytetrafluoroethylene).(ii) Minimum ring diameter, 50 mm; minimum ring height, 15 mm. NOTE 3 Specimens containing inert materials with particle sizes greater than 10 times the diameter may influence the results and should be noted in the reporting. (iii) Minimum internal ring diameter: height ratio is 3:1. (c) Two porous plates of silicon carbide, aluminium oxide, or metal which is not attacked by the soil or soil moisture. The porous plate shall have a permeability not less than 20 times the permeability of the soil. The following requirements shall be met: (i) Plates shall be a minimum of 0.3 mm and no more than 0.5 mm smaller in diameter than the ring to minimize extrusion of soil between the inner face of the ring and the plate. (ii) Top plate shall be loaded through a corrosion-resistant loading cap of sufficient rigidity to prevent breakage of the plate. (d) Dial gauge or transducer (LVDT) with a travel of at least 5 mm and readable to at least 0.002 mm. (e) Trimming knife or wire saw. (f) Filter paper. (g) Oven — designed for soil engineering purposes and capable of drying a sample of soil to a constant mass.
5 Calibration of consolidation apparatus
The calibration shall be as follows: (a) Moisten the porous plates. Assemble the consolidation cell with a metal disc of about the same thickness as the specimen and approximately 1 mm smaller in diameter than the ring in place of the specimen. Place filter paper layers in position as if they are to be used in the test. (b) Load and unload the consolidation cell as in the test and measure the deformation for each load applied for a set period of 30 min per load or unload. (c) Table corrections to be applied to the deformation at the end of each cycle.