The effect of water on the mechanical properties of rocks, such as strength and Young's modulus, has been investigated in many studies. To understand the mechanism of the effect of water on the mechanical behavior of rocks, not only these mechanical properties but also the stress-strain curve, which is one of the most basic data showing the mechanical behavior, should be focused on, and the change of the stress-strain curve with the different water conditions is needed to be known. In this study, the effect of water saturation on the uniaxial compressive strength and the stress-strain curve of rocks was investigated. The uniaxial compression test with alternating loading rate was performed using Sanjome andesite, Tage tuff, Kimachi sandstone and Akiyoshi marble. Inada granite was used for the uniaxial compression test with constant loading rate. The tests were conducted under various water conditions: oven-dried, vacuum-dried, air-dried, air-dried for one day, immersed in water and watersaturated conditions. The test results showed that the stress-strain curve of the andesite, tuff, sandstone and granite changed with the water saturation. On the other hand, the effect of water saturation on the stress-strain curve of the marble was not observed. From the test results, the increase in strength due to decrease in water saturation was discussed. A shift of the peak strength point with the water condition change was investigated, and the relation between the stress-strain curves under the different water conditions was considered based on it.
Cerium-doped barium zirconate (Ce-doped BaZrO3) fine particles with high crystallinity was prepared by a hydrothermal reaction using barium hydroxide, CeCl3, and a Zr-triethanolamine complex. Characterization of the Ce-doped BaZrO3 particles revealed that utilization of the water-stable Zr-triethanolamine complex was an efficient way to introduce cerium ions into the BaZrO3 perovskite crystal structure. The three-way catalytic activity of the Ce-doped BaZrO3 for an exhaust gas conversion reaction was investigated under a stoichiometric condition (CO 0.5%, C3H6 400 ppm, NO 500 ppm, O2 0.49%, H2 0.17%, CO2 14%, H2O 10% in N2). The Ce-doped BaZrO3 exhibited a remarkable low temperature NOx cleaning performance when the Ce-doped BaZrO3 was applied as an alternative for an Al2O3 support.
Although blasting is a quite efficient and economical excavation method, it is rarely applied to tunnel projects close to residential areas due to its environmental impacts, especially with regard to vibration and noise. Two key controls used to mitigate the occurrence of noise and vibration due to blasting are the use of small instantaneous explosives charges and the use of precise delay times to initiate the blast design sequence. An advanced electronic detonator, which has its precision of 0.01% of designed delay time and has made it possible to achieve precise initiation control in blasting, was introduced and used in a tunnel construction site in Japan. Testing of the delay times during blasting was carried out, the test results revealed the specific features and performance of the detonator to control the blasting vibration especially within a short distance of the tunnel face. In previous studies, several ways of simulating blasting waveforms were used. One of these, the Monte Carlo method, in which the production wave was reproduced by superposing a single wave had the potential to give good predictions of the production waves that might occur. Therefore, in this study, a similar way of simulating production waves was carried out. Section peaks in the production waveforms correspond with the detonation of each blasthole. These section peaks were found to follow the Weibull distribution, even though the section peaks might be influenced by amount of explosives, drill alignment, and geological inhomogeneity etc. More detailed simulation with consideration of difference in travel time and the change of the Weibull parameters with distance gives further precise results compared with the real production waves. This study leads more precise method of predicting production waves and of optimum blasting design.
Industrial waste generated in the domestic paper industry in Japan was 5.1 million tons in 2015, and after reduction and recycling, 152 thousand tons of the waste was consequently disposed. Organic sludge (paper sludge), which occupies two-thirds of the industrial waste generated in the paper industry, is incinerated for the purpose of volume reduction and thermal recycling, and then it becomes paper sludge ash (PS ash). PS ash is recycled as aggregate, roadbed material in the civil engineering field and cement raw material, but it is necessary to further expand the application and reduce the final disposal amount. From the above background, in this research, the strength characteristics, the durability performance and the environmental impact of low carbon concrete produced by reducing cement usage to 45% by using PS ash as admixture in addition to fly ash and blast furnace slag fine powder, were investigated. Experimental results show that the low carbon concrete produced in this research has long term strength development, and that PS ash does not contribute to long term strength. Moreover, the clay mineral contained in the PS ash has an effect of reducing drying shrinkage by water retention and expansion. With respect to durability performance, neutralization is promoted by decreasing the total cement amount, while salt tolerance resistance is improved. Frost damage resistance tends to decrease. The elution amount of toxic substances is less than the soil environmental standard value.
2004 年5 月にホンタイ炭鉱で自然発火が発生して以降，ベトナムの四カ所の無煙炭炭鉱と一カ所の亜瀝青炭炭鉱で自然発火が続発している。これらに対処するため，筆者等は断熱環境下で石炭の酸化発熱試験ができる装置を使用して，各炭鉱の石炭試料について酸化発熱特性の試験を行っている。これらのデータについて実際に自然発火を発生している炭鉱の試料に注目してみると，150 ℃以下の低温領域の酸化反応速度が他の自然発火を発生していない炭鉱の石炭試料に比較して大きいことを見出した。即ち，低温域における石炭の酸化反応速度が自然発火の発生と深い関係があるという結論を得た。既存の自然発火性評価方法との比較も試みた。