The results of various studies on the engineering properties of volcanic ash soil are reported by many invesitigators, neverthless, such studies on the volcanic ash soil of San'in district are seldom, and so, the writers have made studies on the engineering properties of loamy and pumiceous soils that produced by volcanic activities called by the names of Daisen and Sanbe volcano. By this experimental studies, the next conclusion were obtained on the Grain-size, Compaction, and Strength analysis. The results are descrived in this paper.
Elastic modulli of porous rocks was calculated from the velocity of elastic waves in regard to changing water content. (1) When the rock specimens are saturated by water, Young's modulus measured by pulse method indicated little change from dry state except loosely cemented sandstones of Tertiary rocks but the modulus calculated by resonance frequency method indicated a little decrement. (2) In most rocks saturated by water, shear modulus indicated 1-7 percents decrement of room dry state, and the modulus of loosely cemented sandstones of Tertiary rocks indicated 70 percents decrement. (3) Comparison with the three Poisson's ratios calculated using the data of pulse and resonance frequency method showed following order of magnitude; νPR≈νP>νR.
Many limestone ores have been reported at the main stream of Niikappu river and its tributaries. These limestone bearing formation is called the Kamui Group which is correlated to middle and lower Jurassic, consisted, slate, chert and schalstein. The Kami Group intercalates many limestone masses at the western flank of the Hidaka mountain range, along Horobetsu river, Shunbetsu river and Koibokushibichari river. Among these limestone masses the largest one was discovered by the Geological Survey of Hokkaido, in 1959, during the geological survey of Idonnappu geological map sheet. This limestone is consist from two parallel irregular lens shape bodies, and the south lens is devided into 2 parts, No. 1 ore and No. 2 ore, by WE trend fault. The north lens is called No. 3 ore. Limestone reserve of No. 1, No. 2 and No. 3 have already been published as 14, 000, 000t (workable 8, 400, 000t), 90, 000, 000t (workable 54, 000, 000t) and 33, 000, 000t (workable 19, 800, 000t) each other. The writer re-examined the No. 2 ore, the largest of all 3, from the stand poin of actual economical mining. He settled the economical mining basal point to 650m level and calculated the reserve, elliminating the low grade quality ore of the eastern and western part. The safety economical ore reserve was considered as 10, 150, 000t. Regarding the quality of limestone, the writer took 81 samples between 300m hight in NS direction and 300m level in WE direction. The average value of CaO is 48.8%. Generally speaking this ore is said to be the middle class ore, though the northern part and the north eastern part of the ore show a little bit lower grade quality than average. Marketting test was operated as follow. 6t of sample, over CaO 50%, was collected and sent to the Shibetsu Sekkai Kogyo K.K. The sample was crashed as 80mm size, put 1 ton into rotary kiln and 950gr of coke was added, repeat this performance for 6 times. Ash-12% Volatile matter-1.5% Fixed carbon-86.1% Cal. -7, 000 K. cal. size-30-50mm. Calcination time is 50.5 hours. Calcination temperature is as follow. preliminary 100°C-500°C heating 1, 000°C-1, 254°C cooling 30°C-400°C Comparison test between the Niikappu lime and the Shibetsu quick lime for agricultural medicine and epidemic prevention use. Namely the Niikappu lime assimilate slower than that of the Shibetsu and easily broken. Made 1, 000cc lime milk and operate precipitation test. Namely the Niikappu lime precipitates earlier than that of Shibetsu. It shows that the Niikappu lime is rather coarse. Mesh test of these precipitates is as follow. The CaO percentage of quick lime is 97.1 of Niikappu and 98.3 of Shibetsu. As a result of above mentioned test, the quality of the Niikappu lime is lower than that of Shibetsu and is said to be the middle or lower class of marketting, and is not suitable for carbide industry, silk reeling, sugar manufacture and iron industry. Seeing from the present economical situation, the limestone mine for cement industry is said to have to sequre 100, 000, 000t of economical reserve. Those limestones along the Niikappu river is composed of No. 1, No. 2, No. 3 and other 2 are bodies. The total reserve of those limestones will be almost near to the figure required. The bottle neck of the exploritation of these limestones is the condition of situation. The nearest twon for constructing cement factory is Niikappu or Biratori, the former is 35 Km apart and the latter is 79Km apart. The road is only 3m width and is under the supervision of the National Forest Bureau. So at present the quick exploritation is seems to be very difficult, however, recent increase of limestone demand for cement use, and the improvement of communication in Hokkaido will give us a hope for the exploritation of limestones of Hidaka district in near future.