In order to determine the fracture toughness of various rocks, the splitting tests under the stiff-load are undertaken on eight kinds of rocks, namely OGINO tuff, KIMACHI sandstone, IZUMI sandstone, EMOCHI andesite, INADA granite, fine grained AKIYOSHI marble, medium grained AKIYOSHI marble and TOHOKU marble.
The rock specimens (200mm×150mm×20mm) in which have a slot are prepared in this test. The crack initiation and the process of crack propagation are studied by the measurement of splitting load, crack opening displacement and crack length. The values of fracture toughness KIC of various rock specimens are determined with the compliance method, and the relationships between fracture toughness and mechanical properties are investigated.
The main results obtained in this studies are as follows;(1) As a result in this test, it is seen that the fracture behaviours of rock specimens are divided into two groups. That is, the fracture crack of rock specimens of one group initiates after the maximum load point in the splitting load-crack opening displacement curve and propagates in a straight line, as OGINO tuff, KIMACHI sandstone, IZUMI sandstone, EMOCHI andesite and INADA granite. The fracture crack of rock specimens of other group initiates at the boundary of grains in rock before the maximum load point and the fracture crack in rock specimens propagateslowly along the boundary, as medium grained AKIYOSHI marble and TOHOKU marble.
(2) From the relationship between fracture toughness and mechanical properties of various rocks, it becomes clear that fracture toughness of rocks increases in proportion to compressive strength, tensile strength and shear strength, and that fracture toughness decreases with the porosity of rocks increas.

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In the Hokuroku District at Akita prefecture, overcoming the difficulties such as the road closure due to the heavy rock pressure is an important problem to decrease the maintenance cost of the drifts.
This paper reports the results of in situ measurements carried out for more than a year at Shakanai Mine as well as those of the laboratory investigations on the core specimen from the mine.
The hydraulic pressure cells shown in Fig. 9 are installed between the ring supports and the rock mass at the 220m level drift as shown in. Fig. 3 and, at the same time the deformations of the ring supports both in the direction of the drift axis and in the plane of the ring supports are measured. The ring supports A and B are in the heavy rock pressure zone of the argillaneous tuff while the ring support E is in the gypsum zone where the rock mass is rather stable.
The laboratory investigations show that the strengths and the viscous constants of the tuff are much smaller than those of the gypsum and the larger water content appreciably decreases those constants as shown in Tables 1 and 2, and that the ratio of the uniaxial strength to the overburden pressure is 0.3-1.0 for the tuff and 1.9-2.1 for the gypsum. Accordingly, it can be said that the heavy rock pressure is caused mainly by the progressive failure and viscous flow of the tuff where the water plays an important role.
The ring supports A and B finally failed by the buckling apparently both in their planes and in the direction of drift axis as shown in Fig. 12 and the loads to them initially increase up to the maximum 6 ton and then gradually decreases as shown in Fig. 11, while the load to the ring support E exceeds the capacity of 9 ton of the pressure cell and its deformation is very small.Fig. 13 shows the load bearing capacities of the two rock mass when the pressure cell penetrates them and this explains the decrease of the load to the ring supports A and B in the tuff zone.
Finally it is suggested that the main failure mechanism of the ring supports subjected to the heavy rock pressure seems to be the lateral buckling rather than the buckling in their planes since the critical load necessary to cause the lateral buckling is much smaller than that in their planes under the condition of the hydrostatic earth pressure.

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The object of this paper is to determine permeability behavior of coal seams with the depth of working places. Test pieces for the experiments are prepared by pressing coal particles into the cylinder of coal of 3cm in diameter and 4cm in length. Emphasis is placed on the effects of grain diameter and applied compressive load on the permeability of coal. The data obtained by flowing nitrogen gas through the coal are studied using capillaric model which may establish correlations between the permeability and the geometry of the porous structure. Principal results of this investigation are as follows.
(1) The Klinkenberg's gas flow equation in terms of molecular slip is valid in the limited region.
(2) The b factor in the Klinkenberg's equation is determined by the square root of the quotient of true permeability divided by porosity, √K∞/φ and the ratio of flow-path length to sample-path length, τ which has been named tortuosity.τ increases as the particle diameter decreases or compressed load increases, varying from 0.42-2.7. If ζ(=√K∞/φ+√1/τ) is defined as the new property of the porous materials, ζ can be provided as a exponential function of compressive load W, that is, ζ=ζ₀eβW, where β is about -1.1, ζ₀ is related with W linerly in log-log plots.
(3) The smaller the particles of coal is, the greater the porosity becomes, but as the compressive load increases, the porosity and the pore radius decrease.

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This paper deals with the problem of gas drainage by a borehole within a bounded circular area under consideration of absorbed gas. The solution of finite gas flow system needs tedious computer calculations. The purpose of this paper is to present a easy method for calculating both the approximate distribution of gas pressure and the gas flow rate.
The gas pressure distribution and the gas flow rate at dimensionless time T can be approximately expressed by Eq.(7) and (9) respectively by use of the gas pressure gradient function C as defined by Eq.(8). The function C can be obtained by using the various C-curves, for example Fig. 2, which are calculated by computer, but C-value can be calculated with the fundamental C-curve of Fig. 5 at arbitrary α, P₀ and R by the following procedure.
1) Calculate T_x corresponding to the R by Eq.(11).
2) Read the C/C_X corresponding to the T/T_X from Fig. 5.
3) Multiply the C/C_X by C_X calculated by Eq.(12). This answer is the C at P=1/50and α=1.
4) Then, calculate the C (P₀>1/50) by substituting the C into C (P₀=1/50) of Eq.(20).
5) Finally, calculate the C at P₀>1/50 and α ≅1 by substituting the C (P₀>1/50) into C (α=1) of Eq.(16).
The gas drainage period is longer in taking account of absorbed gas than of non-absorbed gas and a larger borehole cannot shorten the period so much. The shortening of boreholes interval is more effective for the purpose.

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The authors successfully achieved a field test of air lift pump in Tokyo bay, and accumulated fundamental data on the lifting weight and pressure head loss of simulated nodules.
The lifting conditions used for the test were as follows.
Air lift pipe: 155.4mmφ, Total length of the pipe: nearly 40m, Simulated nodules: 36.4mmφ, specific gravity 1.96, Waterd epth: 50-60m.
This paper describes the analysis of measured values compared to the indoor experimental results which was given in 1st report of the studies.
The results obtained will be summarized as follows.
(1) The lifted volume of water more increases with larger length of submerged pipe. Therefore, the relation between Frg and 1-f_L2 (x)/σ_3/5 was well arranged by the submerged ratio on the basis of the submerged length of indoor experimental apparatus.
(2) The values for lifted water volume, which were calculated by the procedure of 1st report, agreed approximately with the experimental ones, in the range of its actual application.
(3) The friction loss in air-water two phase flow was arranged by the relation between f_L2 (x) and ΔP_2f/ΔP_mo.
(4) The relation between f_L3 (x') and F_rg in three phase flow was also well arranged, considering the submerged ratio.
(5) Concerning the lifted weight of simulated nodules, the calculated values agreed approximately with the experimental ones.(6) The additional pressure loss of simulated nodules was almost neglegible, in the concentration range of this test.

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The present study deals with the applicability of a precipitation method for the differential separation of Cd-CN and Zn-CN complexes in synthesized waste water.
In order to separate cadmium from zinc in synthesized waste cyanide water by the precipitation method, it was necessary to decompose the metal cyanide complexes prior to the precipitation treatment. From a series of tests, it was found that the pretreatment by the addition of sodium sulphide was effective for the selective precipitation of Cd-CN complexes. On the other hand, Zn-CN complexes was decomposed by the treatment of hydrogen peroxide and then zinc and cyanide were simultaneously precipitated by this method.
This method being applied, it is possible to separate and recover both metal complexes as each product.

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The previous observation that free H₂SO₄ concentration affects the passivation characteristics of copper anodes more than the concentrations of Cu²⁺ and Ni²⁺ was investigated in more detail.
It has been found that, (1) Sulfuric acid concentration did not have a sufficiently strong effect upon such solution parameters as DCu²⁺, η and solubility of CuSO₄ to explain its strong passivating effect.
(2) A strong evidence has been obtained that the effect of acid is associated with a change in the slime structure; thus making it thicker and denser with increasing acid level in electrolyte.
A set of experiments of the permeability of water through a slurried bed made of each of the slime samples has shown that a layer of slimes formed through anodization at a higher acid level had lower permeability. Average particle size of the high-acid slimes appears to be finer. Some possible increase in the degree of amorphous fraction of this slime layer has also been discussed.
Slime fall also tends to increase with increasing acid concentration in electrolyte, but to such a small extent that it remains questionable whether this could be a major contributing factor to the dramatic increase in the tendency to passivate.

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For a better understanding of a heterogeneous reaction in the metal sulphide suspension systems, it seems of importance to clarify the effect of the electronic property of the solid particles on an electron transfer through the solid-solution interface. In consideration of the powder sample, the thermoelectric power α which can be evaluated by a simple emf measurement is here taken up and a series of studies have been carried out. This paper describes the method for the thermoelectric power measurement by using pulverized samples of chalcopyrite, galena, white metal, copper and lead concentrates.
A packed bed (7mmH) of the sample is placed in a silica tube (6mm ID) vertically held in a cylindrical heater so as to permit to cause a vertical temperature gradient in the bed. The temperatures of the upper and lower ends of the bed and the thermal emf ΔEare measured by the aid of two thermocouples.
The emf measurements were made first with a large temperature difference ΔT(less than 45°) to establish the method. The results showed a nearly linear correlation between ΔT and ΔE, and then the thermoelectric power was calculated according to α=-ΔE/ΔT. It is found that the coarse galena sample is an n-type semiconductor, whereas the fine a p-type. Re-measured values for the lead concentrates after two months were nearly the same with the previous values.
To ascertain the temperature-dependence of α, the method was further improved so as to measure the emf for a small ΔT(less than 5°). The results obtained follow approximately an empirical eq.,
α=const.±B/T
where Tis the absolute temperature and Bis a constant with the positive and negative sign for a p-and n-type, respectively.
The resistance Rof the bed is simultaneously measured. It is shown that the contact resistance between the particles directly affects the value of R, whereas the temperature-dependence of Rfollows the Arrhenius correlation, R=const.exp (C/T) where C is a constant, the value being independent of the contact resistance.

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