On determining the rock stress from the strains on borehole bottoms by the stress relief technique, we must have an accurate knowledge about the relationship between the change in strain and the rock stress, on which has been left an ample room for investigation.
Firstly the authors, therefore, have carried out three-dimensional analysis of the stress in the vicinity of a boreholebottom by the finite element method and obtained theoretically all the strain coefficients necessary for determining the rock stress.
Secondly the influence of errors in the strains measured upon the stresses determined was discussed by making use of the analysis.
Finally this paper describes the results of stress measurement by this method carried out in the Pombetsu and Bibai coal mines.The obtained results supplied one of the useful materials for elucidating the violent earth pressure phenomena which had been experienced in these mines.

抄録全体を表示

The authors investigated the dredging path of bucket and the shape of dredging rope line on C.L.B.(continuous line bucket) mining system.
At first, we performed the model experiment on theplane which was simulated to the sea bottom, in order to observethe dredging path and the dredging rope line in detail and to grasp the goaf of C.L. B. mining system as a model. Moreover, we made the experiment concerning the dredging path of bucket in the indoor horizontal test tank.
The results obtained are summarized as follows:
(1) Empirical equation concerning the dredging path of bucket is obtained as equation (11) from the model experiment on the plane. i. e. l=K (l₀/1.0)^1-nLnK=0.61 (L₀/l_O) ^-0.38n=0.58 (L₀/l₀) ^-0.13 (ν/V) ^0.28where l₀: rope line distance between the discending and ascending rope lines (see Fig.1) L_O: proiected length of the dredging rope line to L-axis from the bucket which has just dragged out by the dredging rope line to the bucket which has just been off-bottoming (see Fig.1)ν: rotating speed of rope line V: ship speed
(2) It is confirmed that empirical equation (11) is applied to the principal zone of the dredging patn of nucxet experimented in the indoor horizontal test tank.
(3) On the shape of dredging rope line, it is recognized that the constant relationship exists between the tension of ropel ine and theangle formed by rope line.

抄録全体を表示

In this paper, the authors discuss on the application of computer simulation model and “Fracture Mechanics” to describe the failure process of rocks under the compressive load.
Itis well-known that the criterion of the initiation of fracture crack doesnot coincide with the criterion of the propagation of it in compression test. The linear fracture mechanics is applied to interprete the inherent process of compression failure of rocks and the correlation between the initiation and propagation of fracturecracks and the stress-strain diagram.
In order to evaluate the applicability of linear fracture mechanics to the processes ofcompression failure, a computer simulation model is designed. The result of simulation is very similar to the well-known test results on the failure process of uniaxial compression ofrocks. This suggests the applicability of linear fracture mechanics and computer simulation to the analysis of failure processesof rockin compression.

抄録全体を表示

In the previous reports it was shown that the structure of sediments of solid particles in water depends upon bonding force at the contact points of particles and the bonding force consists ofadhesion and friction.
In this report the relations between rheological properties and structure of sediment are described.As solid particles in water are enveloped by thin hydrated layer, the sediment is not fixed at contact points of particles but the particles can mutually be rotated and moved.
The rheological properties depend on only a bonding force. The sediment is called “quasi-solid” by Rehbinder, while the agglomerate such as concrete or pellet is fixed at contact points of particles, so the rheological properties depend on both the strengthof solid and the bonding force at contact points. These agglomerate is regarded as true solid.
Generally the rheological properties of solid particles settled in water shows structural viscosity and viscosity decreases on increasing shear rate.

抄録全体を表示

The segregation roasting reaction of garnierite ore is the complicated one which involves several reaction stages and the nickelrecovery by segregation roasting depends on various factors.
This paper is concerned with the relation between the mineralogical-types of garnierite ores calcined at 1000°C and the nickel recovery by segregation roasting followed by flotation and the discussion on the mechanism of the segregation roasting reaction from the simplified kinetic and thermodynamic analysis.
The nickel recovery from ore of which main mineral in calcine is enstatite and quartz is better than that main mineral in calcine is forsterite.
The experimental results are interpreted qualitatively by the following equation. where q/q∞=Kc (a_NiO) _l.Mq/q∞: nickel recovery (%) M: CaCl₂addition (%) Kc: factor that shows the efficiency of added CaCl₂to ore (a_NiO) ^l: factor that depends on the activity of nickel oxide in ore

抄録全体を表示

The decomposition rate of zinc sulphate in a flow of N₂gas was studied by means of thermogravimetric analysis over the temperature range of 670°-830°C, and the rate determining steps of decomposition and the temperature dependence of therate constants are discussed.
The thermal decomposition of zinc sulphate consists of two reaction stages which proceed successively, namely formation of oxysulphate (1st stage) and decomposition of oxysulphate (2nd stage). It is observed that in the 1ststage of decomposition, the decomposition rate is controlled by two processes, namely interface reaction and transport of product gas through the solid product layer. The 2nd stage of decomposition is controlled by interface reaction alone.
Activation energies for the various rate controlling processes in the 1st stage of decomposition have been determined as follows; for the interface reaction 47.7 kcal/mol at temperatures below 740°C and 30.6 kcal/mol above 740°C, and for the transport of product gas 50.6 kcal/mol below 740°C and 34.0 kcal/mol above 740°C. The activation energy for the 2nd stage of decompositionis 58.6 kcal/mol throughout the temperature range investigated.

抄録全体を表示

The leaching rate and rest potential of ferrous sulfides in sulfuric acid solutions were examined from both thermodynamic and kinetic aspects. The main results obtained in this study are as follows:
1. The leaching rate of non-stoichiometric ferrous sulfides, Fe_1-αS, in an acidic solution is lowered regularly with the increase in a value.
2. This tendency is explained thermodynamically by the decrease in driving force of acid leaching reaction.
3. Ferrous sulfides decompose evolving hydrogen sulfide in an acidic solution. Also, the corresponding amount of elemental sulfur to a value deposits on the surface of sulfide particles, resulting in the retarding of leaching.
4. The rest potential of non-stoichiometric sulfide was influenced bythe concentrations of ferrous ion, hydrogen ion and hydrogen sulfide in the electrolyte and the composition of ferrous sulfide.
However, the concentrations of ferrous ion and hydrogen sulfide do not affect on the rest potential of stoichiometric ferroussulfide.
5. The leaching rate of non-stoichiometric ferrous sulfide is enhanced significantly by lowering the potential of reaction system.

抄録全体を表示