Airborne geophysical survey methods, such as magnetics, electromagntics, and radiometrics, are well known, have numerous applications, and are regularly employed in regional surveys around the world by both governments and private organizations. Technology regarding each of these methods has gradually improved and along with it, the introduction and necessary accuracy in Global Positioning Systems (GPS), the introduction of image processing techniques allowing a greater range in data display compared with conventional contouring, and the availability of multi-client data sets resulting in significant cost reduction.
Airborne geophysical methods have long been recognized as a valuable geological survey tool since the first airborne magnetic survey was flown in 1936 as part of a mineral exploration program. The Metal Mining Agency of Japan (MMAJ) has for more than three decades employed airborne geophysical methods in both its domestic and overseas mineral exploration programs. In general, the surveys provide a wide range of data concerning lithological variation, structure, and features peculiar to mineralization.
Domestically, the MMAJ has employed airborne magnetic surveys since 1969 as part of their regional exploration program, and airborne electomagnetic and magnetic surveys since 1975, initially as part of their research into the application of these methods in the search for Kuroko and epithermal style mineralization. A direct result of this work was the discovery of the Hishikari deposit, Japan's premier gold mine. In 1996, the MMAJ embarked on a new program of high-resolution airborne magnetic and radiometric surveys, beginning in the Hokusatsu region of southwest Kyushu. The results confirmed the importance and application of these sensors in the search for low sulphidation epithermal style gold mineralization. High-resolution geophysical surveys remain an integral part of the domestic survey departments current activities.
Overseas, the MMAJ began its history of airborne surveys in Zaire in 1968 with a fixed-wing magnetic survey. Since that time a range of sensors have been employed around the world for various styles of mineralization, the most recent being a helicopter survey this year in the Bicol region of the Philippines targeting porphyry and epithermal copper-gold deposits.
Although the above mentioned methods have been successfully employed in the search for mineral deposits, they are equally important in other fields. The identification and surveying of faults, slope stability, dam site identification, transport and land-use planning, electric power line construction, underground surveying, and the monitoring of radioactive elements, are just a few of the applications currently employed by both government and private organizations.
Airborne geophysical surveys provide an important and essential data source which should be undertaken as part of Japan National Mapping Program with both current and future multipurpose users in mind. Additionally, it is critical that the government continue to develop the necessary technology concerning data acquisition, processing, analysis, and interpretation, and build upon the high standards, already established within the MMAJ. Such a program is believed to be a matter of national importance.

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Methane hydrates are considered one of prospective energy resources because their estimated amount is huge, tens times as much as that of the natural gases, and their load to the environment is small. In addition, there is a possibility of solving the global warming problem simultaneously by replacing methane in hydrates with carbon dioxide. For this idea to be concrete it is crucial problem to develop controlling technologies of the phase equilibrium condition in methane-carbon dioxide mixture hydrates.
To achieve this purpose, firstly, the revised prediction method of the phase equilibrium condition characterized by precise fugacity calculation and accurate henry's constant estimation is developed. After confirming the accuracy of the proposed method, the control of the phase equilibrium condition by adding other hydrate former or altering the water activity is studied. Main results are as follows.
(1) In the prediction of hydrate equilibrium pressure for the methane-carbon dioxide mixture hydrates, the average absolute deviation of the pressure by the proposed method is ± 3 %.
(2) Controlling method of adding other hydrate former is appropriate for shifting the equilibrium condition toward lower-pressure and higher-temperature side.
(3) Controlling method of altering the water activity is applicable for shifting the equilibrium condition toward higher-pressure and lower-temperature side.

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A shaft with an inner diameter of 6 m has been excavated by blasting in Tertiary soft sedimentary rocks and we have estimated the changes of rock properties, such as deformation modulus, permeability and fracture frequency, of the rock around the shaft. We have performed four kinds of in-situ investigations; borehole jack test, cross-hole seismic velocity measurement, water injection test and borehole television survey. We have carried out these investigations before and after the shaft excavation in the same locations, with the same sets of equipment and through the same procedures for accurate estimation of rock property changes induced by the shaft excavation. The measurement locations have been selected in order to estimate the dependency of the excavation disturbance on the distance from the shaft wall and geological conditions such as lithology and faults.
Within 0.5 to 1 m from the shaft wall, detectable property changes have been observed. In the rock zone, some kinds of deformation moduli have decreased. On the other hand, the number and apertures of fractures have increased and permeability has also increased by 2 ~ 3 orders of magnitude in the rock zone. Blasting damage is supposed to be the main factor which has induced these rock property changes considering strength and stress condition of the rock. Effectiveness of each investigation method in the estimation of excavation disturbance is also discussed.

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Since tunnel boring machine (TBM) is a full-face machine, the face cannot actually be observed. This is disadvantageous when excavating rock, which has rapidly changing characteristics, as is commonly the case for rock in Japan. Therefore, measuring geological characteristics forward of the face is essential.
In the previous paper, a method for estimating the rock strength of face using TBM cutting force, such as thrust, torque and cutting depth, is proposed. In the present study, rock strength along the Hiraya tunnel that mainly consists of granite is estimated from actual excavation data. The length of the tunnel excavated by TBM is 3 km. A full-shielded type TBM having a diameter of 2.6 m was used to excavate the tunnel.
Firstly, the estimated rock strength was compared with the characteristics of rock obtained using the bedrock surveys (inflow water, alteration etc.) and Schmidt-hammer rebound hardness. Estimated rock strength was found to agree well with those found using these surveys. Therefore, the reliability of the estimated rock strength was very high.
Secondly, the relationship between rock mass classification and the estimated rock strength is examined. The results indicated that the higher the rock mass classification, the higher the estimated rock strength. In case of granite, spacing of rock discontinuities and weathering were determined the rock strength. Therefore, the estimated rock strength provides a useful method for properly selecting a supporting pattern for rapidly changing rock mass characteristics.
Thirdly, the relationship between the cutter-head rotational rate and estimated rock strength was discussed because the cutter-head rotational rate of the TBM was variable (4~12 rpm). The lower rotational rate was found to be useful to excavate soft rock.

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In the previous study, a simulator to analyze the behavior of excavated soils in the soil-recycling machine with single shaft was developed. In this study, the simulator developed in the previous study was extended to the soil-recycling machine with dual shafts and numerical simulation on the "Processed volume" and "Distance of mixing completion" was carried out. Furthermore, an experimental apparatus was made and mixing experiments of excavated soils and additives were carried out. From the comparison between the simulated results and experimental ones, the spring constant in the normal direction which is necessary to carry out the simulation was determined for each soil. It was confirmed that the spring constant decreases with increase the angle of internal friction of the soil.
By using this simulator, several simulations were carried out. The effects of some parameters such as paddle inclination angle and pitch of the paddle on the mixing performance were made clear through them.

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In the comprehensive research on the surface subsidence occurred by various underground longwall mining in various countries that was reported previously, the author analyzed relationship between k_i (breaking factor of fallen debris) and various mining methods or various physical characteristics of the rock strata.
Specifically speaking, the author calculated various k_i in the solid-state single seam and multipass mining carried out at Kushiro Colliery, and in various mining applied in England. As a result of the studies, it was found that k_i value drastically changes according to the difference of physical characteristics of rock strata, and the disturbance of rock strata above goaf by secondary mining as well.
With regard to the outcome of the studies, the author proved that the solidification of fallen debris after 2 years of termination of mining at the top lift has sufficient strength to be supported by the shield supports at lower lift under the circumstance of only 100 m below the surface. And the presentation mentioned above was eventually accepted by the Bureau of Mines, United States Department of Interior, and proposal to the US National Project with an idea to apply the Multi-step slicing method was placed to order as a first occasion for the Japanese Coal Mining Industry.

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Restoration of contaminated soils to an environmentally acceptable condition is important. Various methods currently used have advantages and limitations in remediating contaminants in soils. In fact, most successful in situ remediation technologies are restricted to soils with relatively high hydraulic conductivity and can not be used for fine-grained deposits. One of the newer techniques in soil remediation is a method based on electrokinetic phenomena in soils. Electrokinetic soil remediation is an effective in situ separation and removal technique used for extraction of heavy metals and some organic compounds from fine-grained soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils.
In the present study, the distributions of cadmium in the electrokinetic processing of kaolinite under the condition of constant applied voltage are predicted using a theoretical model that incorporates equilibrium chemistry and the results are compared with experimental findings. The results obtained in this study are summarized as follows:
The distributions of pH and cadmium simulated by the model show relatively good agreement with experimental results. The steepness of the pH jump and its influence on the distribution of cadmium are clearly seen. Cadmium accumulates in the region of the pH jump to the cathode. As a consequence of the focussing of cadmium in the region of the pH jump to the cathode, the decrease in the volume of soil to excavate from the site is advantageous. From experiments, it was also found that the progress of electrokinetic processing of cadmium could be grasped to a certain extent by monitoring the local voltage and the current density.

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In order to develop a separation technology for metal recovery from scraps, we have studied density segregation in a particle bed by horizontally circular motion with a constant radius. Differences in the size and density of the particles and also in the velocity and radius of the circular motion affected the segregation of metal particles (Al or Pb) in a separation medium (ZrO₂) were investigated.
The optimum velocity and radius of circulation were 2.5 ~ 3.3 s^-1 and 1.5 ~ 2.0 cm respectively. A new separation system was designed for the purpose of recovering Al or Pb particles from Al-Pb mixture using ZrO₂ beads bed as a separation medium with horizontally circular motion.
Al and Pb were continuously separated from mixture and the Newton's separation efficiency was 0.78. It was possible to recover both Al and Pb with high grade, and the grade of Al and Pb recovered was 99.9 % and 95.4 % at optimum condition.

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Change in the blowing pressure applied to the sintering bed (for the preparation of row materials for ISP) was examined by the experiment using a sinter pot and a mathematical model considering gas-flow across the bed.
The results obtained were as follows:
(1) A pressure drop of the sintering bed changes as the sintering reaction proceeds. It increases at the beginning of the oxidized reaction when the temperature of the bed is still low.Then it decreases as the progress of reaction accompanied by the increase in the bed temperature.
(2) The pressure drop of the bed during the sintering process was mainly attributed to a drying zone, and was comparatively low in the reaction and the cooling zones.
(3) Based on the Erugen's equation, the change in the pressure drop during sintering can be explained by assuming the decrease of an apparent fractional void volume in the drying zone.

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Thermodynamic consideration on melting of copper based alloys with yttrium and gadolinium were carried out at 1,523 ~ 1,723 K and 1,573 ~ 1,773 K, respectively. Solubilities of yttrium and carbon in liquid copper in the presence of C-YC₂ and those of gadolinium and carbon in liquid copper in the presence of C-GdC₂ were determined:
Yttrium solubility in liquid copper under C-YC₂ equilibrium was obtained as
log(C_Y / mass%) = 0.395 + 2.92 × 10^-4T   (1,523 ~ 1,723 K)
Gadolinium solubility in liquid copper under C-GdC₂ equilibrium was obtained as
log(C_Gd / mass%) = 0.684 + 2.64 × 10^-4T   (1,573 ~ 1,773 K)
Based on the results of yttrium and gadolinium solubilities, activity coefficients of yttrium and gadolinium in liquid copper were calculated:
logγ_Y = (- 2.07 - 2.69 × 10³ / T)(1 - N_Y)²   (1,523 ~ 1,723 K)
logγ_Gd = (- 1.56 - 3.82 × 10³ / T)(1 - N_Gd)²   (1,573 ~ 1,773 K)

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