at first and the characreristics of naruraJ drainage is tested to confirm whether the degree of saturation of the material may reach 70 o/. or not.
To make a sample be saturated, water is supplied into the sample in the vessel after vacuuming the air in the void of the sample. After that, water is drained through a small hole on the_bottom of the vessel for 30 minutes and the degree of saturation is measured. In case that the degree of saturation is less than 70 o/,, it is judged that the sample is not liable to liquefy_
3.2 Apparatus
The vessel for the liquefaction potential test consists of main three parts, i.e., the lower vessel, the upper cylinder and the lid, as illustrated in Figure 2.
The vessel should be airtight for vacuuming. The plug for the drain hole is designed for preventing blockade of the hole by particles of the sample.
The recommended capacity of the vacuum pump is not less than 100 litters/minute - 300W.
For consolidatior\ the compaction hammer for Procter C method is used. A set of apparatus for measuring solid density and moisture content, and a suitable weighing instrument are also needed .
3.3 Detailed procedure
The procedure can be sequential]y grouped into the following steps:
(A) Measurement of the capacity of the lower vessel and solid density of the material;
(B) Preparation of saturated sample and measurement of its weight;
(C) Drainage and measurement of the weight of the drained sample;
(D) Measurement of moisrure content;
(E) Calculation of degree of saturation; and
(F) Judgment.
The procedures for steps (A) and (D) should be in accordance with appropriate standards.
For measurement of moisture content, it is recommended to use all material in the vessel. By using the pararmeters obtained through the steps (A) to CD), step (E) is conducted.
3.3.1 Preparation of saturated sample and measurement of weight
The detailed procedure for step CB) is as follows:
(B-1) Prepare 2,400 cm] of the material and dry it;
(B-2) Set up the lower vessel and plug the drain hole:
(B-3) Measure the weight of the empty lower vessel;
(B-4) Set up the lower vessel and the upper cylinder;
(B-5) Remove all water in the lid. Shut all valves of the lid and connect the water line and the vacuum line;
(B-6) Put the lid on the vessel. Start the vacuum pump, open the valve to the vacuum pump and ensure that the vessel is air-tight;
(B-7) Shut the valve to the vacuum pump and open the valve to air,
(B-8) Take off the lid and shut the valve to air;
(B-9) Insert the material in the vessel and consolidate. The number of layers for consolidation is six The amount of the material for each layer is about 400 cm3. Consolidation is executed by dropping the hammer for Proctor C method 50 times for each layer,
(B-10) Put the lid on the vessel and vacuum the air inside the vessel for more than 15 minutes, by opening the valve to the vacuum pump;
(B-11) Shut the valve to the vacuum pump and open the valve to water. When the water
level reaches to about 3 cm above the top of the sample, shut the valve to water,
