Measurements of rock mass around large-scale caverns during excavation have revealed the typical behavior of jointed rock mass ; 1) deformation of rock mass consists of discontinuous displacement and continuous displacement, 2) ratio of these two displacements differs by kinds of rock and others.

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Zinc-air batteries are promising as inexpensive, safe and environmentally benign power sources with high energy density. The active material in the positive electrode is oxygen in air, and thus the negative electrode (zinc) can occupy most of the space in the battery. Primary zinc-air batteries have been used for many applications such as power sources for hearing aid. Rechargeable types have been intensively studied, however, further development is required for its commercialization.
Gas diffusion electrodes consisting of carbon substrate and fluorocarbon binders are widely used in the positive side in order to offer gas (oxygen)-liquid (electrolyte solution)-solid (current collector) interfaces. The poor energy efficiency of the battery arises from low activity of carbon materials for oxygen reduction. High dispersion of active catalysts on the substrate is effective for improvement. Another issue of the air electrode is corrosion of the carbon substrate during oxygen evolution on charging, which limits the lifetime of the battery. Possible solutions are use of graphite or foamed metal substrate. Self-catalytic oxide substrate materials are also attractive, despite of thier low surface area (hence limited high-power capability).
Zinc electrodes exhibit low polarization, however, the shape changes is a major problem for long cycle life of the battery. As soluble zinc species are chiefly responsible, some efforts are made to limit the solubility. It is also effective to decrease the apparent current density in the negative electrode. A new approach for vehicle application is “mechanical charging”, where zinc species formed during discharging are taken from the car battery and are regenerated in a different place (e.g. a factory) while new zinc particles are refilled instantly in the fuel station. Thus electrodes suitable for discharging and charging can be used in the car and factory, respectively. This system requires large infrastructure for zinc delivery and regeneration, hence also social-consensus.

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The mining systems of methane hydrate reservoirs using CO₂ hydrate are proposed, i.e. the artificial block system and the CH₄-CO₂ replacement system. In order to accomplish the concepts, it is necessary to understand the mechanism of formation kinetics of gas hydrates. There are few experimental data on the growth rate of CO₂ hydrate, particularly in the temperature range below melting point of ice, and the mechanism has not been well understood.
In this study, two types of experiments were carried out on formation kinetics of CO₂ hydrate below melting point of ice, using Raman spectrometry and gas consumption method.
Spectra of CO₂ trapped in the hydrate cages were directly observed by Raman spectrometry. The result showed the amount of CO₂ molecules increased with time, and increasing rates depend on the temperature and pressure conditions. From the experiment of gas consumption method, it was found that the growth rate of CO₂ hydrate has two stages. It is indicated that the first stage of growth is rapid growth mode caused by quasi-liquid-layer or locally melted water by the latent heat, and then the latter stage is slower growth mode between gas and ice. In the temperature range of-5 ∼-1 °C, more than 40 % of total reaction gas was consumed in the first stage of growth. Considering that the reaction at the first stage is similar to that of H-L_W-V system, an empirical equation was applied to the experimental results. Reaction coefficients in the first stage were estimated to determine the growth of CO₂ gas hydrate. From these results, we address that proper use of the first stage growth of CO₂ gas hydrate is important to develop the advanced mining systems for methane hydrate.

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Although forced auxiliary ventilation is widely employed at heading faces, it is not easy to lay out the optimum ventilation system for a given heading face mainly because of the complexity of airflow. Therefore, it is essential to obtain detailed knowledge about the influence of the conditions of the ventilation system upon airflow patterns at the face. From this point of view the effects of the position of the outlet of the air duct, the airflow rate from the duct and others are investigated by means of Computational Fluid Dynamics (CFD).
As a result, much important information is obtained concerning the influence of conditions of the ventilation system upon airflow patterns in the face. The results also show that the computation method, which the authors proposed in a previous report, is an effective tool for simulating the airflow under varied conditions of the ventilation system.

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Recently, for the concern of safety in constructions as well as for environmental and economical reasons, an efficient small-diameter shallow tunneling method has become increasingly important for outside plant engineering such as water supply, gas, electricity, telecommunications. In particular, for construction work near existing facilities, an underground tunnel excavated by the pipe-jacking is becoming increasingly popular to avoid adverse effects.
Basically, the pipe-jacking system is involving the pushing or thrusting of the drivage machine through the concrete pipes ahead of jacks. The method utilizes the mud slurry that is formed around the pipes for stability of surrounding soil. However, it is not well understood the behavior of the soils and mud slurry around the pipes.
From this point of view, this paper discusses the effect of mud slurry and stability of surrounding soil by means of the fundamental property tests and the laboratory tests. Moreover, this paper analyzed the performance of the behavior of mortar and mud slurry as the rehabilitation method by means of two-dimensional Eulerian-Lagragian seepage analysis.

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In the present study we have experimentally investigated DRA Method (Deformation Rate Analysis Method) to understand the effect of confining pressure and stress level on the estimation of previous stress. In addition, the DRA and AE Methods were applied on the estimation of the in-situ stress from the rock cores that were obtained from Ikeshima Colliery. The following main results were obtained.
(1) The previous stress can be obtained by the objective criterion that is settled for reading the laboratory data.
(2) The confining pressure did not have any significant influence on the stress estimation in DRA Method.
(3) DRA using the strain data in the test under a confining pressure enabled us to accurately estimate the axial stress that was previously applied under a confining pressure, even if the previous stress was very close to the uniaxial compressive strength.
(4) DRA and AE Method that are carried out at a laboratory can be applied on the in-situ stress measurement method.

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One-dimensional injection analysis was performed to understand the infiltration process and the filling process of grout materials into the voids of homogeneous ground. Regarding the analysis of the filling process, the material transport equation considering the filtration theory was introduced and used. Generally, a cement-based grout can be treated as a Bingham fluid characterized by plastic viscosity and yield stress. Regarding the analysis of the infiltration process, the equation of the plug flow related to the Bingham fluid inside the circular pipe was expanded and used. The results of this analysis are as follows:
1) After the injection, the change of discharge by grout injection shows a rapid decline, and it becomes gradual afterward.
2) As the concentration of grout thickens, the accumulated discharge of the grout material decreases and the accumulated cement amount increases conversely.

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Batch leaching behavior of ground chalcopyrite (median particle diameter 6 μ mm) was investigated anaerobically by a shaking flask method. The experiments used 0.1 mol dm^-3 sulfuric acid solutions containing 0.25 mol dm^-3 ferric ions and known concentrations of ferrous and cupric ions at 303 K. The initial pulp density of the chalcopyrite was 10 kg m^-3.
When 1.00 mol dm^-3 of ferrous ions were added, copper extraction proceeded in three steps: (1) an induction period, (2) a leaching period, and (3) a stationary period. This extraction behavior can be interpreted by the following reaction model: in the induction period, copper is extracted slowly by the direct oxidation of chalcopyrite with ferric ions and the redox potential of the solution decreases due to the consumption of oxidant ferric ions. When the solution potential becomes lower than a critical potential, a leaching period, intermediate Cu₂S that is oxidized faster than chalcopyrite is formed by the reduction of chalcopyrite and copper extraction rate becomes high. When the solution potential decreases further, a stationary period, Cu₂S oxidation and copper extraction stop.
Based on this reaction model, the effects of the initial pulp density and the initial concentrations of ferric, ferrous, and cupric ions on the leaching behavior were simulated numerically. As a result, it was predicted that the induction period could be eliminated by adding more than a critical amount of cupric ions with ferrous ions and that the stationary period can be eliminated by solution potential regulation during the leaching.
The simulation agreed with the experimental results. When 1.00 mol dm^-3 ferrous ions and 0.05 mol dm^-3 cupric ions were added together, 56 % copper extraction was obtained after 9 days without an induction period, then extraction stopped. Further when the solution potential was regulated by the addition of ferric ions, 80 % of copper was extracted in two weeks. On the other hand, without the ferrous and cupric addition and the potential regulation, copper extraction was only 11 % even after 27 days.

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The sponge gold (99.92 % pure) has been leached with ammonium thiosulfate solution. In this investigation, the gold leaching rate (extraction rate) and the thiosulfate oxidation rate (consumption rate) have been studied on the effects of CuSO₄, (NH₄)₂S₂O₃, (NH₄)₂SO₄, NH₄OH, stirring speed and retention time. The copper ion acts as a catalyst in gold dissolution, on the other hand, it also accelerates oxidation of thiosulfate (consumption). It was found that the best gold extraction was obtained at 12 hours under following optimum conditions:0.8 ∼ 1.0 mol / l (NH₄)₂S₂O₃, 0.03 mol / l CuSO₄, 2.0 ∼ 3.0 mol / l NH₄OH, 0.4 ∼ 0.5 mol / l (NH₄)₂SO₄, pH 10 ± 0.2 and 150 rpm. The thiosulfate oxidation is about 15 % of the initial concentration.

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塩酸溶液からの鉄(III) の抽出がLIX 63 (5，8-ジェチル-7-ヒドロキシ－6 －ドデカノン　オキシム，HR) の灯油溶液の使用により種々の条件で検討された。有機相への抽出物が赤外線吸収および紫外可視吸収スペクトルの測定により調べられた。結果として次のような平衡式が提出された。すなわち2 > pH > 1 でFe-(OH)²⁺(aq) + 2HR (org) ↔ Fe (OH) R₂ (org) + 2H⁺(aq) ; [HCl] = 1 -10 mol dm^-3 でFeCl₃ (aq) + HCl (aq) + HR (org) ↔ HFeCl₄↔HR (org)。そしてpH 領域での溶液および高濃度の塩酸溶液からの抽出物はそれぞれ2量体化学種FeR₂ (OH)₂ FeR₂ およびC_3v 対称の単量体化学種FeCl₃ ↔ HCl ↔ HR として存在するものと推論される。

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