To prevent liquefaction of materials which may liquefy, the condition (4) should be complied with. Based on this consideration, the requirement of SOLAS Convention, mentioned in section 1.1, is provided.
3 Methods for judgment of liquefaction potential of solid bulk materials
The liquefaction potential of a material may be examined by evaluating the possibility of liquefaction of the material under saturated condition. In the case that liquefaction phenomenon does not take place in saturated sample of a material under specified acceleration condition, the material is judged as not liable to liquefy regardless of moisture content. Liquefaction phenomenon of granular materials, however, easily occur when the material is artificially saturated. It can, therefore, be said that the method for evaluating the liquefaction potential of a saturated material provides too conservative results in view of the application of the requirement.
The liquefaction potential of a material may be evaluate in terms of the upper bound of degree of saturation of the material at shipment, because liquefaction hardly occur in case of low degree of saturation. In view of this, we developed a new test procedure, named Liquefaction Potential Test (L.P.T.), as written in section 4.
4 New test procedure for evaluating liquefaction potential
In the test, the sample of a material is made saturated in the mould at first. Next, the water contained in the sample is drained through a small hall on the bottom plate. Then, the moisture content and the degree of saturation of the sample after drainage are measured. In case that the degree of saturation is less than 70 %, it is judged that the material is not liable to liquefy. The first version of the test procedure is detailed in the paper submitted by Japan to the second session of DSC Sub-Committee (3). The compaction procedure for the test was amended as pointed out by Poland (4).
The apparatus for the test is illustrated in Fig. 1. The inner diameter and the depth of the mould are 146 mm and 100 mm, respectively. The volume of the specimen is around 1,700 cm3. The diameter of drain hole is 3.1 mm.
The outline of the test procedure is as follows:
(1) Measure the specific gravity of solids by using pycnometer;
(2) Measure the capacity of the mould, i.e., the volume of the specimen, and the tare weight of the mould;
(3) Dry the sample;
(4) Set the extension collar on the mould and insert the sample in the mould under the specified compaction condition;
