A lot of methods have been developed in order to evaluate mechanical behavior of rock mass containing discontinuities. The methods can be classified roughly into three categories. First one is to model the rock mass which contains many and unspecific discontinuities by replacing it with an equivalent continuum. Second one is to analyze failure behavior of rock mass, modeling all of the discontinuities as they are, for the rock mass in which specific joints exist distinctly. Third one is to analyze formation of shear band as the result of successive development of micro fractures and accumulation of those, which depend on heterogeneity of rock mass.
These numerical methods have been rapidly developed since the decade of 1960 when FEM analyses were introduced into rock engineering and computer came into wide use, and further development are still being carried out. Historical changes in development of the numerical methods and the significant features of those are described in this report.

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Uniaxial compression tests were carried out on rock specimens which were modeled on a bench cut-quarry or cliffs of various shapes in order to clarify behavior of near-surface crack growth in rock mass. Exfoliations at highly compressed parts and detachments of convex parts as results of crack growth were observed in the experiments. Numerical simulation on crack growth based on 2D-DDM was carried out in order to explain the experimental results. The authors proposed a new criterion for crack growth since predictions by using widely known Sih's maximum tensile stress theory were slightly different from the observed results. The new method takes shear stress as well as tensile stress near crack tip into account and gave results that were similar to the observation. A series of compression tests on rock and mortar specimens having a slit or an initial crack was conducted in order to clarify the applicability of the new method. Profiles of the most observed cracks were similar to predictions by the proposed method.

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In soil mechanics, a transparent tri-axial vessel is frequently used, however, in rock mechanics, a metal vessel has been used to withstand higher confining pressure. In this study, a transparent vessel made of an acrylic acid resin with tensile strength of 75 MPa was designed and manufactured for tri-axial compression test under confining pressure up to 10 MPa.
Every component of the vessel was designed with safety factor more than four. Paying special attention to safety, confining pressure was increased over the designed value until its failure. The confining pressure at the failure was more than 55 MPa and daily use at 10 MPa was considered to be safe. It was also revealed that an annular transparent tube made of an acrylic acid resin did not break into pieces, but only a vertical crack was extended.
Preliminary tri-axial tests were conducted for Tage tuff and Dotan that were deformed easily under the confining pressure. Many photographs were taken by a digital camera, and vertical and lateral deformations / strains were read out successfully.

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Characteristics of the erosion strength of crystalline rocks is presented and discussed, which is of fundamental importance for determining the pure water jet drilling performance. A formulation of the erosion strength is presented from the dimensional analysis of a rectangular particle separation from bottom surface, assuming the anisotropy of the microscopic tensile strength of rocks, and the effect of rock stresses originally acting perpendicular to the drilling axis is discussed in consideration of the stress concentration at the bottom surface. The validity of the present formulation is successfully clarified by analyzing the pure water jet drilling experiment of marble and granite under a biaxial compression, together with the effect of the anisotropy of the tensile strength. As concerns to the chipping upon water jet drilling, it is shown that the incidence of chipping upon drilling increases with increasing of the confining pressure.

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In waste office paper photocopied and printed by laser printers, toner ink is used as the printing medium and it cannot be decomposed in alkali by saponification different from the case of conventional oil ink. Therefore, to achieve a high degree of liberation, waste office paper has conventionally been comminuted to fine particles by strong agitation. However, this method not only makes toner so fine that separation becomes even more difficult but also makes it difficult to make high quality regenerated paper because the paper fibers are cut. In this study, a toner disintegration method by a relatively soft agitation force with the use of kerosene as a softening agent for toner ink has been investigated. The liberation degree of toner was 3.8 % by the conventional method using only NaOH and increased to 98.1 % by using undiluted kerosene and to 80.1 % by using 1 % kerosene suspension. As the remained toner parts were connected to only one or few paper fibers in these kerosene treatments, the liberation degree would become 100 % if these kinds of toner were also counted. The use of surfactants as dispersion agents for kerosene decreases the liberation degree because it interferes the softening of toner. It was also confirmed that an NaOH treatment in advance of the kerosene treatment is important to increase the liberation degree of toner.

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Recently, a new method for deinking waste officer paper by magnetic separation after hetero-coagulation of magnetic and non-magnetic toner has been reported. The selection of flocculants which can produce large and strong coagulates is very important to reject toner coagulates effectively in this method. 1-octadecanol whose melting point is 60 °C is used in their report. Coagulation was carried out at 70 °C and then the 1-octadecanol liquid was cooled to make strong solid coagulates. Although high toner liberation must also be achieved before magnetic separation to obtain high deinking and paper recovery, no investigations on liberation methods were done in that report. A paper disintegration method using kerosene was reported in our previous paper, and it was shown that almost 100 % of toner liberation could be attained. As kerosene has ability to soften toner, strong coagulates may be produced by that adhesion when used as a flocculant. In this study, the size of liberated toner by the kerosene disintegration method has been investigated, and the bonding strength between toner particles by adding kerosene as a flocculant has been compared with that by 1-octadecanol. After these investigations, coagulating and deinking properties of kerosene and that of 1-octadecanol have been compared by rejecting toner coagulates with a NdB magnet. From the results, close to 100 % of deinking can be expected with little paper loss even in room temperature because large and strong coagulates can be produced by the use of kerosene as a flocculant. When kerosene was used in the disintegration and coagulation stages, the average coagulate size was 1114um and 98.4 % of deinking was attained by separation with the NdB magnet.

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Sodium bicarbonate is so unstable that the rate of decomposition is strongly affected by even trace amount of water in the powder. Variously hydrated species may be formed on the surface as decomposition products from sodium bicarbonate to sodium carbonate. In order to clarify the decomposition-mechanism and chemical-stability of the material, a method of quantitative analysis has necessarily been developed to determine the minute amount of free water and crystalline water related to variously hydrated salts. Preceded to the present work, therefore, four analytical methods established so far were examined to select the suitable method for the present object. The Karl-Fischer titration method combined with a moisture evaporator was finally selected by adding an analytical process, in which the dehydration amount-time profile is deconvoluted into several different peaks corresponding to the state of water. The fractional evaporation of various states of water enables the quantitative analysis without any pretreatment of the sample. This fractional quantitative analysis may be explained by the difference of thermal-stability among those of sodium bicarbonate, sodium carbonate hydrate and sodium sesquicarbonate.

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鉄の還元溶錬や鉄基合金などの二次回収物の処理で重要なCu-Fe-As3 元系スパイス相を取り上げ，スパイス相中の成分活量の導出ならびにスパイス相とカルシウムフェライト系およびシリカ飽和の鉄シリケート系スラグ間におけるヒ素および銅の分配比の測定を試みた。1,423 K におけるスパイス中の銅および鉄の等活量線はγ-Fe固溶体と共やくする液相線がCu-As 合金側にかなり大きく張り出していることに起因し，スパイス組成に対してかなり特徴的な形状を呈した。カルシウムフェライトスラグースパイス間のヒ素の分配比，L_As^s/cは，γ-Fe固溶体飽和組成域で10^-4オーダーのかなり小さな値を示すが，鉄の活量が小さくなると，急激に増大した。鉄シリケートスラグースパイス間の L_As^s/cは，同－スパイス組成において，カルシウムフェライト系の1 / 3 程度の値に留まった。スパイス成分の活量，活量係数，スラグ中のヒ素および銅の活量係数，平衡酸素分圧などの基礎熱力学データを用いることにより，ヒ素および銅の分配比の挙動を合理的に説明することができた。

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By using a solid mixture of silica (SiO₂) with water-soluble inorganic salts as pore constructing agents, porous materials were fabricated through the coagulation / phase separation process. During the formation of the porous structure in the SiO₂ / inorganic salt system, dispersibility of the mixture of silica sol with inorganic salt and the SiO₂ / inorganic salt ratio are considered to strongly influence the coagulation/phase separation. In this study, we elucidated the dispersibility during the mixing of silica sol with inorganic salt, and the influence of the SiO₂ / inorganic salt ratio in the solid mixture on the coagulation / phase separation. When SiO₂ sol is mixed with inorganic salt in the solution, the surface electric potential is varied depending on the pH of the solution. Hence, dispersibility affected by the pH of the mixture is considered to strongly influence the resulting coagulation / phase separation in the SiO₂ / inorganic salt system. In this system, the SiO₂ / inorganic salt solution mixture had good dispersibility under the acidic condition of pH less than 4. On the other hand, gelation abruptly occurred after mixing SiO₂ sol with inorganic salt under the conditon of pH nearly 7. Furthermore, the SiO₂ / inorganic salt solution mixture had poor dispersibility under the acidic condition of pH less than 4, and the resulting porous material was found to have broad pore size distribution. To clarify the influence of the SiO₂ / inorganic salt ratio on the coagulation/phase separation, solid mixtures having various ratios of SiO₂ / inorganic were prepared. SiO₂ / inorganic salt (KBr) with the volume fraction ratios widely ranging from 10 / 90 to 90 / 10 could form the monodispersed pore structure. Remarkably, the thickness of the framework in the porous material increased with the increase of the SiO₂ volume fraction. Namely, the thickness of the framework as well as the pore size or the pore size distribution was influenced by SiO₂ / inorganic salt ratios.

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To improve the photocatalytic activity of TiO₂ coated hollow volcanic glass spheres, vanadium or tungsten hydroxide was doped on the surface of volcanic glass in the aqueous solution of NH₄VO₃ or 5(NH₄)₂O·12WO₃·5H₂O. The volcanic glass was ballooned by heat treatment in temperature ranges of 960 ∼ 1,000 °C, and these hydroxides were translated into metallic oxides in this process.
On increasing the vanadium loading, the crystal size of anatase TiO₂ on the surface of volcanic glass spheres increased and the phase transformation of anatase to rutile occurred. As the result, the removal rate of NO gas was decreased. Whereas, when the tungsten was doped, there was not almost the change of the crystal size of anatase TiO₂ and the phase transformation of anatase to rutile was not observed. The crystal size of anatase TiO₂ appeared about 12nm and the removal rate of NO gas was increased with raising the tungsten loading. The maximum removal rate of NO gas was observed with adding the tungsten of 0.54 wt%.

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The catalytic activity of the metallic ultrafine particles is known to change by their oxidation state. In this study, an attempt has been made to discuss the control of the oxidation state of Ni by synthesizing the ultrafine alloy particles through the liquid-phase reduction method. Zn plays as an electron donor to Ni nanoparticles so that the catalytic activity of Ni is controlled.

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100 °C，常圧下において，Na2WO₄，Na2MoO₄，CaCl₂，PbCl₂ の混合水溶液からCaWO₄-CaMoO₄-PbMoO₄-PbWO₄ 系鉱物を合成した。粉末X 線回折の結果によると，CaWO₄-CaMoO₄ 系とPbMoO₄-PbWO₄ 系の合成物は完全固溶体を形成している。一方，CaWO₄-PbWO₄ 系とCaMoO₄-PbMoO₄ 系では固溶体はそれぞれ端成分付近に限られている。CaWO₄-CaMoO₄ 系合成物は短波長の紫外線を照射すると，淡青色から黄色の明るい蛍光色を示す。一方，PbMoO₄-PbWO₄ 系固溶体では，PbMoO₄ 分子を0.5∼1 mole% 含む合成物のみが淡緑色の暗い蛍光を示す。

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It has been speculated that there are large oceanic methane hydrate deposits adjacent to Japan, and it is important to elucidate the mechanical and chemical properties of the hydrate to develop commercial technologies for identifications and extracting hydrate concentrations to utilize these resources. The occurrence of methane hydrate is controlled by severe conditions such as high pressure and low temperature and the decomposition processes of synthetic methane were observed microscopically hydrate under the conditions of a wide range of temperatures and atmospheric conditions. The results are summarized as follows:
(1) Microscopic observation of thin sections of synthetic methane hydrate is available using a sample sowed by microtome using a tungsten knife covered with a plastic plate. However, it is very difficult to reduce the hydrate to a thickness of about 0.02 mm, which is the common thickness for rock thin sections. Hydrate and ice are identified under crossed nicols based on the differences in crystal systems.
(2) Occurrence of the common decomposition in methane hydrate processes were observed at temperature increases of between 2 °C / min and 10 °C / min and in the temperature range of -100-0 °C. When methane hydrate was maintained at 5 °C or 10 °C on the surface of the thin section, it took about 10 or 100 minutes respectively for the hydrate to decompose into methane and ice. When the temperature of methane hydrate was increased at a high rates, a small amount of ice gradually formed until temperature reached 0 °C, and then a large amount of ice was shortly formed near 0 °C. When the rate of temperature increases was low, ice was formed slowly and at an even rate. We speculated that this phenomenon was related to self-preservation. Based on the results of this study, we found that for a long period of time is required to decompose methane hydrate into methane and ice or water.

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Roof lowering wave phenomenon was first observed by O. Jacobi, German researcher at longwall faces where mechanized powered supports were introduced in West Germany. Since Kushiro Colliery, Taiheiyo Coal Mining Co Ltd.,was going to introduce fully mechanized longwall mining system to their Numajiri area, it was essential to scrutinize this phenomenon, because if wave should have happened at the face, full collapse of the supports, particullarly at the rear leg position by reciprocating roof lowering is likely to occur.
The author therefore carried out series of measurement at single prop and powered support faces, and introduced the results of measurement for basic design of the UU shaped frame type 12-leg powered supports.

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