A kind of rock and water outburst occurred several times at the deep level excavation of the shafts or the inclines in Yubari New Coal Mine in the 1970's. In this incident a large amount of groundwater containing dissolved gas flowed out with scaled rock and a crater was formed at the outburst trace.
In this study, the formation mechanism of the above crater was considered on the basis of the observational and the experimental results in order to obtain a prevention measure against the outbu st. Moreover, the shape of the crater was examined by applying the probability theory on material strength to the bending fractures of the scaled rock.
From these results, it became clear that the vertical angle of the crater depended on the coefficient of uniformity of the rock strength and the hydrostatic pressure gradient in the cover rock. And, the observational facts, which the vertical angle of the crater in sandstone was larger than that in shale, could be explained well. Consequently, it became possible to estimate the grouting depth at the prevention works site against the rock andwater outburst.

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In an underground limestone mine recently developed, the stress changes in rock around the primary opening, which were induced by excavation of the secondary openings above or below the primary opening, are being monitored by means of pressure capsule. The floor displacement induced are also being measured by a special displacement meter coupling a laser beam and two solar batteries. Initial rock stress state and a tangential stress state at the primary opening were measured by double fracturing technique and stress compensation technique using lune-shaped flatjack, respectively. Furthermore, induced change of a pillar stress was predicted numerically.
The paper describes the outline of the excavation process, the measurement systems and the measured results which are compared with the predicted stress change with respect to excavation progress.

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In order to discuss how we can obtain a more accurate two-dimensional distribution of seismic velocity in a rock mass, field measurements for tomographic analysis were performed. The accuracy of reconstructed image is greatly controlled by the accuracy of data. Therefore, at first, in order to accomplish more accurate travel time data, travel time data which were read out initially was corrected by using several checking methods. Then, in order to achieve an accurate analysis, an optimum inversion technique and optimum required parameters are selected. The velocity distribution which is obtained as the result of tomography analysis shows good agreement with both the result of laboratory measurements and that of geological observations. The applicability of seismic velocity tomography for exploration of ore deposits and for evaluation of in-situ rock mass is discussed.

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A new kind of static rock splitter has been developed taking advantage of TiNi shape memory alloy which attains a maximum recovery force of about 600MPa. The splitter consists of compressively prestrained TiNi rods and a pair of two-layered wedge type platens of steel, and requires no accessory equipments other than heating apparatus. To examine the performance of the splitter, theoretical analysis for the crack initiation and laboratory test using rocklike materials have been performed. It is confirmed that the splitter is not lacking in terms of performance. The breaking time is extremely shorter than those of conventional breaking processes.

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The advanced borings are used in many countries to prevent the gas outburst in the coal mines and their effects are widely proved. But the site experiments are not so easy, for they require a lot of time and funds.
The author made a model experimental study to investigate the effect of the advanced borings on the stress relief. A three-dimensional model experimental apparatus of about 1: 80 geometrical scale was used. The boring diameter, the number of borings, the spacing of borings and the strength of model coal seam were selected as the parameters of the experiments. As the model rock mass, the gypsum plate was used and as the model coal seam, artificial seam composed of the mixture of water, gypsum and diatomite. The scale of the stress and the strength was 1: 40.
The effect of the stress relief was measured by the degree of stress relief defined by the author. The relationship between this degree and the above mentioned experimental parameteres are reported. The strength of the coal seam and the boring diameter are the most important parameters which determine the effect of stress relief.

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Concern with prediction of blast sound propagation, a new method has been developed based on a solution of sound wave theory and spectral analysis such as the Fourier transformation. This method calculates the wave form change during propagation directly based on following procedure; Firstly, the original source sound pressure-time curve is converted to the frequency components by the Fourier transformation and the propagation loss during propagation of each frequency component is calculated by using an acoustic theory and then the sound pressure-time curve is derived by the inverse Fourier transformation of the propagated frequency components which are given by the subtraction of the propagation loss from the original spectrum of each frequency component. Based on the new calculation method, control methods of frequency component and sound level of blast sound due to delay blasting have been also discussed.

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This paper deals with the buckling problem of partially liquid-surrounded circular cylindrical shells under torsion to analyze systematically the stability of cylindrical offshore structures. A theoretical analysis is performed by means of the Galerkin method on the basis of the Donnell-type equation for shells, taking the effect of the axisymmetric deformation due to the static liquid pressure into consideration. Calculations are carried out for both simply supported and clamped shells and the torsional buckling loads k_s are determined for various values of the shell geometric parameter Z, liquid pressure parameter p_x and liquid depth ratio l₀.
The main results obtained are as follows:
(1) The torsional buckling load ratio k_s decreases monotonously with an increase in the values of l₀ and/or p_x. With an increase in p_x, the buckling wave number ratio β increases for small value of l₀ and decreases for large value of l₀.
(2) The effects of the shell geometries Z on the torsional buckling load ratio k_s are almost negligible for the simply supported shells.
(3) The effects of the boundary conditions on the torsional buckling load ratio k_s are almost negligible, especially in case of l₀=1.0.
(4) The effects of the surrounding liquid and the torsional load on the prebuckling and buckling deformation are clarified by means of the contour map representation.

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As volume of wastes increases at an extraordinary rate, it is often difficult today to find the place for dumping and treatment of large volume of the wastes. In Japan it is an urgent problem to decrease volume of wastes and to recycle them.
Therefore we try to utilize organic wastes from timbers as activated carbon material for environmental protection. Bark of Ezomatsu. Karamatsu and Todomatsu imported from USSR are selected for material of production test of activated carbon.
Bark material is dried at the temperature 50°C in 48 hours, ground and sorted under 4mm. From thermal analysis (TG, DTG, DTA) data optimum temperature of activation is found to be ranged from 400°C to 600°C.
The test of chemical treatment of bark sample by ZnCl₂ is performed at the temperature of 400, 450, 500 and 600°C. Yield specific surface area and adsorption of methylene blue, benzene, trimethylamine, stylene, dimethyl sulfide and 1-butanethiol are measured for activated samples.
Activated carbon samples produced in these experiments have the same or higher adsorption capacity than the commercial activated carbon.

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In the present study, a series of adsorption tests by using strong acidic cation exchange resins were carried out on a pregnant solution containing thiourea complexes of gold, iron, copper and zinc, and then elution tests were conducted by using different kinds of eluates. From the results obtained in this experiments, it was found that Amberlite 200C was the most effective among the ion exchangers used for the recovery of Au (CS (NH₂) ₂)₂⁺. By the use of Amberlite 200C, it was acertained to be able to separate gold from other metal thiourea complexes through adsorption and elution processes.

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Purification of iron oxide obtained from Iron Precipitation of the Zinc leaching residues with Na₂B₄0₇ flux have been investigated by use of the recrystallization method.
And, the effects of retention time at 1, 200°C, cooling rate, iron oxide/flux ratio, CuO and NaF additions on size, purity and the yield of hematite crystal were tested.
The main results obtained are as follows:
(1)The size of hematite crystals decreased with the increasing cooling rate from 1°C/min to 10°C/min.
(2) The purity of hematite crystals was about>99.8% of Fe₂0₃, and the contents of Zn, S, As were 130-300 ppm, 7-20ppm and about 30 ppm, respectively.
(3) The yield of hematite crystals increased up to>80% with increasing cooling rate and the iron oxide/flux ratio and with an increase of NaF addition.

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The investigation and experiments were carried out on purification of butyl phosphoric acid, 2-ethylhexyl phosphoric acid and 2-ethyloctyl phosphoric acid. Chemical properties of alkyl phosphoric acids purified by this method were measured, which were distribution ratio between oragnic and aqueous phases, acid dissociation constant and interfacial tension.
The distribution ratio of mono-esters is much lower than that of the corresponding di-esters. Values of the distribution ratio are 5.2, 49 and 570 for butyl, 2-ethylhexyl and 2-ethyloctyl phosphoric acids, respectively. The mono-esters are fairly strong acids whose dissociation constants are 10^-2.1, 10^-2.3 and 10^-2.3 for butyl, 2-ethylhexyl and 2-ethyloctyl phosphoric acids, respectively. The mono-esters are more surface active comparedwith the corresponding di-esters, except butyl phosphoric acid which has high solubility in an aqueous solution. The interface coverage of mono-esters is calculated from interfacial tension measurements according to Gibbs' equation.

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