The extraction of geothermal energy from hot dry rocks in the earth's crust has received wide attention. An abundand amount of geothermal energy could be recovered from hot dry rocks by circulating fluid through crack-like reservoirs which are created by a hydraulic fracturing technique. During the extraction of geothermal energy, the surfaces of the crack-like reservoirs are cooled by the fluid and the thermal contraction of the rock occurs. When the stress intensity factors at the border of the crack-like reservoir attain the fracture toughness of rock, the reservoir begins to propagate at the border. Therefore, in the design of crack-like geothermal reservoirs, the fracture mechanics study of a water-filled crack including thermoelastic effect is needed to control the mechanical behavior of the reservoirs.
This paper is concerned with the shape of a vertical two-dimensional crack-like reservoir in the earth's crust on the basis of the theory of quasi-static thermoelasticity. The surrounding rock is assumed to be a continuum which is homogeneous and isotropic with respect to thermal and elastic constants. By using the singular point method, a set of singular integral equations for density functions derived. The singular integral equations are solved by means of the collocation method and the inversion formula. Numerical calculations are carried out to find the shape of the crack-like reservoir, and the opening displacement of the reservoir against time is shown. The variation of the volume of the reservoir is also plotted against time. An approximate formula is also proposed to estimate the volume of the reservoir.

抄録全体を表示

The strength of material is usually determined from the fracturing load through brief calculation formula assuming simple stress distribution in the specimen. However, complicated stress distribution may be caused in the specimen under some kind of shear test.
The authors have performed single-plane shear test using the rotary-die-type simple shear testing apparatus, which was suggested from I. B. G. standard plan and improved by Kobayashi. They have analyzed the boundary conditions between the specimen and the shearing tool and confirmed it by the measurement. Then they have analyzed elasto-plastic behaviour of the specimen considering the above conditions.
It is suggested from the results obtained that inclination between the vertical plane and the shear-plane prescribed must not be far from 27°50' for significant shear test.

抄録全体を表示

Shock waves generated by the explosion of gases or explosives contain a great deal of energy. It will decrease inits quantity as traveling further from the explosion sourse. In the present investigation studies have been carried out on the phenomena of the decreasing process of shock wave as its object. Experiments were done in a small test gallery, whose diameter, length and wall thickness are 450mm, 10m and 6mm, respectively. Setting No.3 Kiri-dynamite on the corner cutting mortor, test blastings were practised several times. The shape of angled mortor is 120mm in diameter and 1m in length having 5×5cm right angle notch in its direction of axis. Blastings were always executed towards the exit of gallery. The velocity of shock wave is obtained by measuring the arrival time of shock wave to each measuring point. The pressure of shock wave was calculated from the velocity. As a result of the present study, it is concluded that pressure (P), velocity of shock wave (V) and its traveling time (t) are the functions of distance (R). Namely, the incident pressure P (atm) has a relation of
P=k₁/R^2/3,
the velocity V (m/msec)
V=k₂/R^1/3
and traveling time t (msec)
t=k₃·R^4/3,
where coefficient k₁, k₂ and k₃ are bound as k₁ ∝k²-₂∝k²-₃ R is the distance between measuring & blasting point.

抄録全体を表示

Support deformation of gate roadway was monitored at four longwall panels of Kushiro Colliery in order to determine the design criteria for construction of the liner road which had been newly developed instead of advancing tail gate. The mining depth of those panels was 660m below the sea level, and the mining geometries of them were almost similar to each other. All the liner roads were constructed within 7m from ribside and used for return air ways.
The measurement revealed that there was little deformation- of support within 20m behind coal face, but after that the deformation increased with advance of the coal face as shown in Figs. 4, 8, 11 and 15, which was approximated by a piece-wise linear curve with respect to distance from the coal face, Fig. 17. Also the support deformation varied periodically along the liner road as shown in Fig. 5, 9, 12, and 16 so that the predominant wavelength was, for instance, 71, 33 and 14m in a typical panel. The upper half arc of the circular ring support or the arch member of the arch-invert support was not only lowered, but also deformed toward the ribside of the panel, Figs. 6 and 13. Furthermore the uplift of floor was profited by level surveying along the liner road.
The results obtained from measurement, therefore, imply that the support deformation of the liner road may scarecely be affected by caving of the immediate roof just after advance of powered support, but may be dominated by main roof lowering and floor heave accompanied by face advance.

抄録全体を表示

The object of this work is to measure the terminal settling velocity of a single sphere and the apparent terminal velocity of spheres in the fly ash slurry. In addition, it has been attempted to apply the equation (8), which was available for the terminal settling velocities of particles in the water, to those in the fly ash slurry.
To eliminate the accelerated part of fall from the measurement of the terminal settling velocity of a sphere, the experiment on the accelerated motion of a sphere particle was carried out and the experimental values were in close agreement with the calculated values by equation (1).
From the numerical solution of eq.(1), the empirical formulas for the modified dimentionless accelerated time T* and distance L* were then derived as eq.(10) and (14).
The terminal settling velocity of a single sphere in the fly ash could be measured beyond the accelerated region by means of eq.(1) and the apparent viscocity of the fly ash slurry was evaluated from the velocity. Substituting these values into eq.(8), the apparent terminal velocity of spheres in the fly ash slurry could be approximately estimated.

抄録全体を表示

This paper deals with the pressure loss of Bingham plastic fluid flow through packed beds. With help of tube-bundle model a friction factor and Reynolds number relationship for laminar flow is derived as Eq.(16).
The present experimental investigation covers the range of Reynolds number defined by Eq.(21) from 4×10^-3 to 8×10² and of Bingham number up to 3×10³.
It is confirmed by the experiment that the flow behavior in the range of Reynolds number defined by Eq.(15) up to 10 shows the laminar state.
An empirical equation of friction factor defined by Eq.(14) for laminar flow obtained as Eq.(25). It is observed that 362 out of the 489 data in laminar flow were within ±10% of the values calculated from Eq.(25).

抄録全体を表示

In the author's 3rd report, the reformative result of the pyrolysis reaction, to reduce oxygen contents in low-rank coal by autoclave, was submitted.
In this report, it has been discussed that about brown coal, above all low-rank one like lignite, the carboxyl group, to cause high moisture contents and to promote spontaneous conbustion, in the reformed coal, is remarkably reduced in comparison with one in the raw coal, by the reaction to be based on the same method in 3rd report.

抄録全体を表示

Large quantities of coal ash are produced in the world every year by coal-burning powerplants, and have long been a major waste disposal and environmental problem. In accordance with this increase in coal ash, some research programs have been prepared with the goal of utilizing as much of waste as possible.
This waste represents a premined source of several metals. If economic recovery of these metals is realized, the waste has been treated in our country as a important resources.
This research was done in order to provide the fundamental effects of chemical and physical properties of coal ash on a sulfuric acid leaching process. The sample of coal ash from Poland has been mainly examined by means of photomicroscopic observation, electron microprobe analysis, spectro graphic analysis, quantitative analysis, size separation, X-ray diffraction, thermal gravimetric analysis and differential thermal analysis.
The main results obtained are summarized as follows:
The major elemental constituents of coal ash are Si, Al and Fe, together with minor amounts of Ca, Mg, Na, Ti, C and S.
The mineral content of coal ash are primarily mullite (3A1₂O₃·2SiO₂), with the presence of hematite (Fe₂O₃), magnetite (Fe₃O₄) and silica (SiO₂).
The logarithmic probability plots of the screen analysis for sample showed the cumulative weight oversize percent and the cumulative weight undersize percent of each size fraction as a function of the particle diameter. The results should be useful in recovering the metals which are contained in a coal ash in a sulfuric acid leaching process.

抄録全体を表示

Water and aqueous glycerol solution of viscosity of 5 and 10 cp were poured through a rectangular vessel of 60cm long and 20cm wide at the flow rate of 300, 500 and 700ml/min, and the residence time distribution was measured by injecting diluted red ink solution as a tracer. The liquid height, h, was maintained at 3 and 6cm. Mixed model was applied, and the volume fractions of piston flow (Vp/V) and complete mixing (Vc/V) were found to be 0.10 and 0.90, respectively, when h was 3cm. They were 0.05 and 0.95when h was maintained at 6cm. The C-functions in the form of Eqs.(18) and (19) were derived, respectively.
A layer of carbon tetrachloride was placed at the bottom of the vessel, and water was poured over this layer at the flow rate of 300, 500 and 700ml/min. From the measurement of the residence time distribution of water, the volume fraction of dead zone was found to be 0.20 to 0.40 which decreases with the rise of the flow rate. The C-functions of Eqs.(20) to (22) were obtained for the flow rate of 300, 500 and 700ml/min, respectively.
The flow patterns were photographed, and its relationship with dead volume was discussed.

抄録全体を表示

A prototype agitated cell for suspension electrolysis was made and continuous sulphidizing electrolysis was carried out to reduce copper concentration lower than the legal requirement for discharge
The cell consists of a vertical cylindrical agitated compartment with an internal diameter of 40cm, about 50cm height and 4 fin type-electrode compartments vertically attached in radial fashion on the cell wall of the compartment. Each fin compartment is divided with 2 vertical diaphragms of a cation exchange membrane into 2 anode chambersand a cathode chamber, the latter being connected with the agitated compartment through an upper inlet and a lower outlet in the cell wall. The catholyte suspension of 12.9 kg elemental sulphur per 62 dm3 in the agitated compartment is agitated with wings rotating at 800rpm (13.3 S^-1) so as to permit to circulate through the cathode chamber. An acidic sodium sulfate solution is independently circulated through the anode chambers with 4 pumps.
An acidic feed solution containing 1.0 to 1.2g/dm³ Cu was continuously fed to the agitated compartment and the electrolysis was performed stably up to a cell current of 120A at a feed rate of 151dm³/h. The feed rate was controlled so as to maintain the suspension potential at a set value of 0.20V (Pt vs. AgC1 E), at which the residual copper concentration was reduced to 0.2ppm. The current efficiency was about 100% and the power consumption was 2, 970 and 4, 600kWh/t-Cu at 60 and 120 A, respectively. The cell enabled passage of currents up to 180A, but the potential measurement and the feed rate control was disturbed by the high current.
For scale up, the capacity of the cell described can be increased by increasing the number of fins without a reduction of the ratio for (diaphragm area)/(cell volume).

抄録全体を表示