| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥6,500,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1996: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Research Abstract |
It is great importance to understand of the mechanism and to know of the extent of the weathring of rocks. In order to clarify the relationship between the mechanical properties, the slaking properties, and the inherent structure of rocks after the repetition of dry and wet condition, the laboratory tests such as the slaking durability test and so on were carried out. The results show that the inherent voids or/and cracks of the rocks were increased as the repetition of dry and wet condition. It is considered that lower mechanical properties and the slaking durability index were obtained under the repetition, because grown-up voids or/and cracks behave like a weakness plane. Much of the research in the slaking durability test is concerned with the effect of the dry temperature, the moisture content, and the number of cycle on the slaking phenomenon. Namely, we discussed the dependence of the parameters which were obtained by the grain size accumulation curve on the fragmentation produc
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ts after the slaking durability test. The parameters consisted of the deviation of the 50 % effective diameter in the grain size accumulation curve, the weight ratio of the products under the 2mm sieve, the uniformity coefficient, the summation of absolute value of the residual ratio difference, and the specific surface area. The results of the slaking durability test would be presented that the slaking phenomenon is increased with high deviation of the moisture content without the effect of the dry temperature Moreover, the parameter such as the deviation of the specific surface area can be determined as the slaking phenomenon in quantity.
A number of approaches have been developed to determine the fracture toughness which is expressed as the magnitude of the propagation characteristics of cracks. The fracture toughness test requires the specimen to be in the precisely prescribed shape. However, it is often difficult or practically impossible in some cases, to prepare the specimen as required, with weak rocks or potentially weathering rocks. From this point of view, we discussed the index such as the tensile or the compressive strength of rocks, the rock impact hardness number (RIHN) , and the quartz content of rocks for prediction of the fracture toughness. The results show that the fracture toughness has a generally good correlation with the RIHN and the quartz content of rocks. It indecates that the propagation process of cracks depends on the fragmentation property and the inherent structure of rocks. Moreover, AE technique was tried to explore the possibility of its application in the estimation of the propagation characteristics of cracks. It is shown that the propagation characteristics of cracks and the propagation process during the slaking durability test can be predicted by using AE technique. Less
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