The Deformation and failure characteristics of rocks have been elucidated by uniaxial stiff tests and general triaxial tests. It is desirous to consider the post-failure properties of rocks on the design of underground excavations but few attempts have been carried out on it.
Firstly the authors have made a study of the formulation of failure criterion and post-failure behavior of rocks considering results of uniaxial compression, tension and triaxial compression tests. Secondly they have developed a method of elasto-plastic analysis of rock stress and deformation around underground excavations.
The applicability of this method has been investigated by comparing the results of analysis of the deformation around a circular tunnel with those of model experiments. It has been found that the elasto-plastic analysis gave better results than the conventional analyses, though the both did not show satisfactory accordance.

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the search coil.This semiconductor device is somewhat similar to well known magneto-electric converting devices, except that the sensitivity of this device is several hundred times greater than that of them.
The most significant feature of the new system is its independency of the sensitivity on the rope speed, which substantiated the inspection virtually at any speed including motionless state.
Several units of the device, whose number is consequential to its physical dimensions and also to the inherent directional sensitivity, are laid on a pair of split bobbin to encircle the rope simultaneously at a close two sections to form a twin annular detector assembly.
Serial or cummulative connection of all the units in one section covers the effect of lateral vibration of the rope, and the differential connection between the both halves of the twin results in a satisfactory enhancement of overall noise immunity.
The output voltage ranges approximately ten times greater than the e.m.f.on the conventional search coils at a pertinent magnetization, and may be fed into an appropriate differential amplifier for following signal processing.
For general inspection, the number of the units in each half should not be consistent with the number of strands in the rope in order to reduce the periodical noise caused by the inevitable periodic change in radial clearance between the relief of rope surface and the annular detector assembly while the rope passes.
This system with another version of the detector assembly may also be applied to measuring the let out length of a rope, determining the elongation and examining the uniformity of rope strand, in which assembly the number of the units in each half should be consistent with the number of strands.

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The studies concerning fluorite were carried out following the previous paper (3).When the pH of solution was varied, the isoelectric point of fluorite was pH 6.65 (Fig. 3).When an equivalence point (EP) is defined as the pH at which any selected pair of positive and negative ions have equivalent concentrations, EP (CaOH⁺, HF₂^-) was pH 6.7 (Fig. 4). There was a good agreement between the isoelectric point and the EP (CaOH⁺, HF₂^-).And also, the other results showed around the same pH or pH region, that is, the pH value at the zero H⁺and OH^-demand was about pH 6.4 (Fig. 1), in any initial pH of fluorite suspensions after enough time pH would be converging on an equilibrium pH value between pH 6 and 7 (Fig. 2). At pH 10, the isoelectric point was about pCa2.7 (Fig.5).In alkaline region, it was observed that F^-on the surface was exchanged by OH^- (Fig.7).
In determining the potential of fluorite in an aqueous solution, ionic species playing an important role are H⁺andOHand also C_a⁺⁺and F. CaOH⁺and HF₂^-could be considered as the ionic species, too.
About adsorption of SDS on fluorite, both chemical adsorption forming surface Cadodecylsulfate (Fig.13) and electrostatic adsorption should be considered.On the other hand, adsorption of DAA is mainly electrostatic.

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Infrared absorption spectra of glasses in NiO-SiO₂, NiO-SiO₂Al₂O₃, MgO-SiO₂-Al₂O₃-NiO systems were measured in the range of 400-1400 cm^-1by KBr method. The chloridizing roasting of Ni in MgO-SiO₂-Al₂O₃NiO glasses was studied in order to discuss the relationship between IR spectra and reactivity of Ni in these glasses.
The obtained results indicate that there are two types of silicate anions, one of which is very highly polymerized state like silica, whereas the other is SiO₄type which has a structure like Ni olivine in NiO-SiO₂glasses. The Al₂O₃added to the silicate has a role of a homogenizer in the glasses.
It was also found that the volatility of Ni in chloridizing roasting decreased with increasing Al₂O₃in MgO-SiO₂-NiO glasses when the ratio of MgO/SiO₂was constant. This suggests that the activity of NiO in these glasses decreased with addition of Al₂O₃.

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Hydrolysis of acidic ferric sulphate solutions of various concentrations with the addition of zinc sulphate has been investigated in an autoclave at the temperatures of 185°C and 200°C. The results obtained were as follows;
1. When the hydrolysis of ferric sulphate solutions was at equilibrium, the final concentrations of iron in the solutions increased with the increase of sulphuric acid concentrations, but at the same sulphuric acid concentrations, those of iron decreased considerably with the addition of zinc sulphate.
2. In the hydrolysis of ferric sulphate solutions, ferric oxide, Fe₂O₃, was precipitated at lower sulphuric acid concentrations. But the stable region of ferric oxide was extended with the addition of zinc sulphate in the ferric sulphate solutions.
3. In the hydrolysis of ferric sulphate. solutions at 185°C in the absence of zinc sulphate, Fe₂O₃is stable below 55.8g/l H₂SO₄, and Fe (OH) SO₄is stable above 55.8g/l H₂SO₄. When zinc sulphate was added to the solutions, Fe₂O₃is stable'over a wide range of conditions. For example, at 185°C, when respectively about 70g/1 Zn and 100g/l Zn as zinc sulphate were added, F_e2O₃is stable up to 84.2g/l H₂SO₄and 93.0g/l H₂SO₄.
4. In the hydrolysis of ferric sulphate solutions at 200°C, in the absence of zinc sulphate, F_e2O₃is stable below 69.3g/l H₂SO₄, and Fe (OH) SO₄is stable above 69.3g/l H₂SO₄. When respectively about 70g/l and 100g/l Zn as zinc sulphate were added, F_e2O₃is stable up to 103.8g/l H₂SO₄and 112.5g/l H₂SO₄.
5. When zinc sulphate was added to the solutions, the relations between the concentrations of iron and those of sulphuric acid over the ferric oxide stable region are expressed _by the following experimental equations. At the temperature of 185°C log [F_e (g/l)] =4.91 log [H₂SO₄ (g/l)]-8.93 about 70g/l Z_nas zinc sulphate log [Fe (g/l)] =8.21 log [H₂SO₄ (g/l)]-15.28 about 100g/l Z_nas zinc sulphate At the temperature. of 200°C log [F_e (g/l)] =3.82 log [H₂SO₄ (g/l)]-7.23 about 70g/l Z_nas zinc sulphate log [F_e (g/l)] =5.46 log [H₂SO₄ (g/l)]-10.31 about 100g/l Z_nas zinc sulphate
6. The equilibrium diagram of the ternary system Fe₂O₃-SO₃-H₂O in the presence of zinc sulphate at 185T, and 200°C were established from the experimental data.

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