Elasto-plastic deformation of a circular opening under bi-axial stress condition has been analyzed on the basis of the theory of plastic potential. The plastic area surrounding the opening has been analyzed by the coupling method of the boundaryelement method and the characteristics method, presented in the first report. To evaluate the elasto-plastic displacement in the plastic area, the method of characteristics has been successfully applied, and the Mohr-Coulomb's failure criterion is adopted for the plastic potential.
Hydrostatic pressure problem has been firstly discussed, and it is noted that the radial displacement at the inner surface of a circular opening is mainly depending upon the ratio of hydrostatic pressure to the uniaxial compressive strength of rock, and the influence of the coefficient of internal friction is comparatively small when the associated flow rule is applicable. Moreover, the present numerical analysis has been compared with the analytical solution and proved effective.
For the bi-axial stress condition that the ratio of initial principal stresses is greater than 1/3, it is made clear that the partial yielding around a circular opening proceeds to the yielding of whole surface with increase of initial stress. By analyzing the relationship among the intensity of initial stress, the depth of plastic area and the elasto-plastic displacement at the innersurface, it has been concluded that the maximum surface displacement due to the excavation is not affected very much by the ratio of initial principal stresses and can be evaluated from the analytical solution under hydrostatic pressure condition.

抄録全体を表示

In this study, the acoustic emission activity occurring prior to coal and gas outburst had been observed in the drivages at intersection with the outburst-prone coal seam in SUNAGAWA Coal Mine since 1979. During the observations, the acousticemission activities from the coal and gas outbursts were successfully monitored three times.
As above observational results, the acoustic emission activity occurring after blasting increased and decreased remarkably in the approaching process of driving face to the outburst-prone seam. These results prove that the fracturing activity in the source of coal and gas outburst became at a high degree temporarily. After that the fracturing activity became at a low degreegradually. Consequently, the increase and decrease in

抄録全体を表示

The type of slurry flow behavior attained in a given pipe diameter is largely determined by the settling velocity of solid particles in a fluid. However, it varies as a function of slurry concentration C, particle diameter, and particle shape. Since the slurry are composed of irregular shaped materials in most slurry pipeline application, design requires an accurate knowledge of the effect of a shape factor used for evaluating the particle shape on terminal settling velocity V_t and on hindered settling velocity V_ε
The object of this paper is to find the method of estimating Vε of irregular shaped particles in a fluid bounded by rigid wall. It is well known that a sedimenting suspension and a fluidized bed are similar hydrodynamically, therefore experimentswith a variety of materials were carried out in batch fluidized systems, covering the particle Reynolds number range 180 to 1400.
Based on the experimental results we discussed the modified Richardson's equation which could be describedby: V_ε/V_t=Ko (1-C) ⁿ
The index n is a function of the particle Reynolds number and of the dimensionless number depending upon the configulationof suspended particles, while the factor Ko represents the wall effect and increases with area index of particles. Experimental data were analysed taking into account the particle segeregation and the types of behavior of fluidized systems. Moreover, the generalized equation of V_ε was derived, and then the quantity ψ(_ε) representing the mutual interferenceof particles was determined by experiments.

抄録全体を表示

In order to make a simplified analysis on the lateral vibration of the off-shore structure constructed with four legs and a platform, the same method as one used in the first report was again applied in this analysis by replacing the structure with two-dimensional portal frame, evaluating its flexual rigidity and then by transforming the structure into the equivalent lumped-mass model. Furthermore, the validity of this method was examined by the model experiments carried out on two kinds of the 4 leg-structures.
The main results obtained are as follows:
(1) The natural frequency obtained by the simplified method which utilizes Theory (2) or Theory (4) proposedin this study, coincides with the experimental frequency within the error range that is about 0.06-5.47%.
(2) As the ratio of the distance between legs and their span-lengths is smaller, the error of the natural frequency calculated by the above-mentioned method is more reduced and so its precision of calculation becomes higher. Therefore, the proposed method would be useful enough to analyse the natural frequency of the lateral vibration of the general offshore structure which has the small value of the above-mentioned ratio.
(3) Furthermore, this method gives the fairly well estimated value with respect to the amplitude of lateral vibration of the structure, since the error involved in the estimation is only about 9-13% at the fifth period of vibration.

抄録全体を表示

The moving velocity of particles captured on a single wire is one of fundamentals for determining characteristics of continuous high gradient magnetic separation.
In this paper cross section of deposit layers' configuration was analitically calculated in order to search for the moving velocity of particles. The results obtained were good agreement with experiments.
On the basis of the results, the force acting on deposit layers was calculated.
A model formula (1) expressing the moving velocity of deposit layers (V_p) was derived from the force.

抄録全体を表示

Based on the Davis' model regarding ball throw motions in a rotating cylindrical container an optimum operating condition for ball mill grinding utilizing the falling energy of balls has been estimated.
According to Davis the orbit of ball motion is characterized by two kinds of track; one in a parabolic path and the other in a circular path along the wall of container, and at certain conditions of mill speed and mill filling the trajectories of balls do not interfere each other. Therefore, every realizable, ball track without any interference is imagined to be reproducible in a determined area within a mill profile, so that the summation of the falling energies of ball become possible in those conditions.
In the course of estimation the values bearing on the potential energies derived from the ball trajectories were referred to.
Assuming that the optimum mill speed for the best grinding effect should be deduced by the maximum of the integrated values above, an experimental confirmation using a ball mill of 20 cm inner diameter was undertaken.
Optimum mill speed estimated for cylindrical container without wall linings is 87.4% of critical mill speed.Grinding effects have been measured at various ball fillings as a function of mill speed.
Experimental results at reasonable mill filling have verified our estimation considerably well.

抄録全体を表示

Interfacial tensions in molten copper-fayalite slag and Cu-matte-fayalite slag systems have been measured by sessile drop methodcombined with X-ray radiophotograph. Interfacial tensions between copper and fayalite slag were found in the range of 0.8-0.6 N/m^-1at 1473 K and decreased with the increase of oxygen partial pressure at the interface. Oxygen played a role of an interfacial active element in the system. While interfacial tensions between Cu-matte and the slag were rather small at low mass% Cu in Cu-matte, they became large when mass% Cu in the matte increased.
Spreading and floating coefficients in the copper-fayalite slag system were negative. On the other hand, negative spreading coefficients and positive floating coefficients were obtained in the Cu-matte -slag system. It has been understood thatmatte particles may be floated with gas bubbles in the slag. Floatation behaviour of matte particles with gas bubbles in the fayalite slag was able to be directly observed at 1473 K in the fayalite slag by X-ray radiophotograph technique.

抄録全体を表示

Extraction of Mo and W from the single component solution and the binary solution and stripping of both metals with various aqueous solutions were investigated by using Alamine 336 as an extractant. On the basis of the extraction and stripping properties, separation methods of Mo from W were studied from the two main aspects. The one is the viewpoint that W could be selectively extracted under the aqueous condition of pH around 1, because the failure of separation of Mo from W is due to the formation of complex polynuclear ionic species between Mo and W. It is considered from-the solution chemistry of both metals that the complex polynuclear species are not almost formed in aqueous solution of pH below 1.
The other is the point of view that after simultaneous extraction of Mo and W, Mo would be selectively stripped from the organic phase with the aqueous solution containing complexing agents or W could be selectively crystallized as ammonium paratungstate from the organic phase with ammonia solution.
Though any attempts to separate Mo from W do not produce sufficient results at the present stage, the interesting extraction and stripping data of Mo and W are represented in the paper.

抄録全体を表示

The iron-reduction distillation process consists of two successive reduction stages for the mixture of iron oxide and zinc oxidewith a Fe/Zn mole ratio of 2 as a starting material. Experimentswere carried out to investigate the reduction stages by using zinc calcine as a zinc oxide source. Thermodynamic estimations on the bahavior of minor elements were also made. The results are summarized as follows:
(1) On the first reduction stage with a CO₂/CO gas ratio of 0.1 at temperatures 973 and 1073 K, iron oxide was preferentially reduced to metal, while zinc oxide was only slightly reduced. Particularly at 973 K, reduction of zinc oxide hardly proceeded, which suggested that 973 K ofa lower temperature was favorable for the first reduction stage. Zinc ferrite, ZnFe₂O₄, was easily decomposed, but other zinc compounds such as ZnS and Zn₂SiO₄were lessreducible than ZnO and remained after the first reduction stage.
(2) On the second reduction stage in a vacuum of 1 Pa at 1173, 1273 and 1373 K, all the zinc compounds were completely reduced to zinc vapor by the metallic iron, which had been previously reduced on the first reduction stage, within 60, 20, and 10 min at the respective temperatures. Zinc recovery of 91-98% was attained on the second stage in successive treatment of the first and second reductions. The iron contents in the residues were 83-86%, which suggested that the residues could be returned to the first reduction stage or sent to the steelmaking process.
(3) From the thermodynamic estimations it was considered that some minor elements which are more noble than iron were reduced to metals on the first reduction stage. Cadmium was found to be volatilized above 70% during the first reduction, and most of lead was vaporized during the second reduction. Since most of coexisting minor metal values such as gold, silver and copper are concentrated in the metallic iron, their recovery with high efficiency can be expected by magnetic separation of the residue.

抄録全体を表示

The oxidation of arsenious acid with ozone in aqueous solutions and sulfuric acid solutions was investigated. In this work, six variables were considered as those affecting the rate of oxidation:(1) rotation speed, (2) initial arsenious acid concent- ration, (3) arsenic acid concentration, (4) partial pressure of ozone, (5) pH and (6) temperature. The rate of oxidation with ozone was also determined in sulfuric acid solutions, up to 14.7 M H₂SO₄. Zero order kinetics with respect to arseniousacid arsenic acid concentrations and first order kinetics with respect to partial pressure of ozone were observed. Gaseous ozonedissolves rapidly in the aqueous solution and the equilibreem between gas and liquid is established, so that the rate of oxidation given by Ozone acts as a strong oxidant for arsenious acid below 7 M H₂SO₄

抄録全体を表示