Old concrete specimens were examined carefully under a stereomicroscope and with an image analyzer to clarify the characteristics of durability failure related to age. Microcracks and pores in concrete specimens more than forty years old were coated with cyanoacrylate mixed with fluorescent paint, and then microscopically visualized under ultraviolet light. Various patterns of cracks or pores in old concrete specimens, such as typical microcracking and rims within the outer parts of aggregates, were revealed. However, clear distinction of these microacracks and pores in usual thin or polished sections was difficult. Image analysis including image sharpening, edge preserving smoothing, thresholding, and line thinning reveals that the total microcrack length per square millimeter in specimens of old concrete shows good agreement with P-wave velocity determined by the usual method.
This method is useful in the observation and evaluation of durability failure in old concrete specimens.

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銅, 鉛, 亜鉛, ニッケルおよびマグネシウムなどの非鉄金属製錬工程において排出されるスラグについて, その構成成分をX線回折法ならびに光学顕微鏡観察により同定した。また, JIS標準ボールミル法によりワークインデックス (粉砕性指数: Wi [kW-h/t]) を測定し, これに関連するビッカース硬度 (Hv [N/m²]) ならびに密度 (ρ [Mg/m³]) との相関関係を検討した。亜鉛製錬スラグのワークインデックスは, 析出している多量の金属成分のため測定不能であったが, その他のスラグのワークインデックスは約15～27kWh/tであった。概して, スラグのワークインデックスは, 石英, 長石等の無機酸化物鉱物の測定値に比べて大きい。また, 非晶質物質が卓越するスラグのワークィンデックスは結晶質スラグのそれより大きな傾向がある。既存のデータを含め, ワークインデックスと密度およびモース硬度H_M (=4.52・logH_v-37.96) の積との相関を検討した結果, 試料が非金属かつ結晶質物質の場合は以下の関係式で整理できた。
Wi=0.42 (H_M・ρ) +6.56 [相関係数γ=0.83] この相関関係を利用すると, 亜鉛製錬スラグの非金属かつ酸化物結晶質部分のワークインデックスは, ビッカース硬度および密度の測定値から16kWh/tと推定できる。

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The final goal of this study is to develop the computer-controlled robots for finishing the inside surfaces of tunnels as are expected.
In this study, some control algorithms to measure the distance between the head of the ultrasonic sensor and a point on the surface of an object were developed, and the outlines of some objects with the surfaces of simple slopes and rocks have been measured by using the robot manipulator with the ultrasonic sensor.
When the sloped surfaces of the objects are covered with some emery papers and measured by the robot system, very accurate values on the shapes of surfaces of the objects can be obtained automatically and speedily. Especially, the time required to measure every shape of the objects can be reduced remarkably by the continuous measurement of the above-mentioned control algorithms where the ultrasonic sensor continuously detects the distance between the sensor and the object by moving the robot manipulator.
Furthermore, it is proved that the allowable measurement-angle of the sensor is clearly extended as the roughness of surface of the object increases and as the slope angle of its surface decreases.
The measured values of rocks, moreover, are found to be considerably accurate within the error of 2.0mm. Therefore, the measurement system considered in this study could be satisfactorily available in measuring the inside surfaces of actual tunnels.

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This paper presents numerical modelling of powered supports for analysing the interaction of supports with the strata surrounding them. Finite element analyses were carried out for fourteen types of 2-leg shields, nine types of 4-leg chock shields and nine types of 4-leg shield, allowing us to compare their performances with one another. The main results obtained from the numerical analyses are as follows:
(1) The principal direction of the stiffness of powered support reflects its attitude, and provides a suitable indication of its performance of controlling strata.
(2) The inclination of hydraulic legs determines the principal direction of stiffness of 2-leg shield. Relatively weak roof strata are controlled by 2-leg shields better than by the others.
(3) The principal direction of stiffness of 4-leg chock shield is controlled by an algebraic sum of the inclination angles of the front and rear hydraulic legs. 4-leg chock shields whose front legs tilt forward and rear legs incline backward cope well with the condition of strata that both the roof and floor are moderately strong.
(4) The principal direction of stiffness depends solely on the inclination angle of the front hydraulic legs in 4-leg shields. Relatively weak floor condition is less harmed and better accommodated by 4-leg shields than by the others.

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In practice, rock mass is neither subjected to pure creep or pure relaxation but to a torce-cisplacement condition dictated by surrounding rock. But few are available in the literature about this problem.
Generalized relaxation test of Sanjoume-andesite and Kawazu-tuff was conducted under uniaxial condition. The generalized relaxation test investigates the property of time-dependent decrease (or increase) of stress under increasing (or decreasing) strain. Concretely, the increment of force-displacement relation was kept as follows;
ΔF_R-γ·K_R·ΔY_R=0
where ΔF_R is the increment of force, ΔY_R is that of displacement, K_R is the stiffness of rock sample in the elastic region and 7 is the direction factor of relaxation. Considering all possible boundary conditions (the relationship of the stress-strain), the direction factor of relaxation can be all real number.
By plotting all results on a stress-strain diagram, it can be said that the stress-strain curve shrinks as time goes by. In other words, rock characteristic line changes with the lapse of time.
A strain rate at an arbitrary time in the region where the strain rate is signified by a continuous increase is inversely propotional to the time up to final failure. If this law is applied to rock mass, the failure of underground constructions may be predicted.

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転動ボールミル内における個々のボールの2次元的運動を, 非線形スプリングー非線形ダッシュポットから構成される拡張ケルビンモデルを用いた個別要素法により数値解析した。モデルの粘性係数は, ボールとミル壁間での不完全反発におけるデータから決定した。個々のボールの動的な運動のシミュレーションは, 個別要素間に仮想的に挿入されたスプリングの非線形完全弾性とダッシュポットの非線形粘性ならびにニュートンの運動則に基づいている。動的なボール運動の計算値を実際のミル内におけるボールの運動と比較し, ミル回転速度やボール充填率の影響について検討した。その結果, 本稿で提案したモデルシミュレーションは, ミル内のボールの運動をほぼ再現して表示できることがわかった。シミュレーションから再現されるボールの運動は, ボール充填率やミル回転速度に依存することが示された。また, 本シミュレーションによって個々のボールの衝突頻度や衝突速度が推算可能であることもわかった。

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A rock cutting rig has been designed and installed to investigate disc cutter performance in circular cutting mode as well as in linear one. A program of disc cutting experiment was performed in the circular cutting mode by using a single commercial disc cutter of diameter 150 mm and edge angle of 90° for seven different types of rock. The experiments resulted in determining semi-empirical formulae for thrust F_T, rolling force F_R and lateral force F_L acting on a disc cutter, written by F_T=K_TD^1/2P^1/2S^1/2F_R=K_RP_S^1/2F_L=K_LP^3/2
where D is a diameter of disc cutter, P is penetration of disc cutter and S is tool space. The coefficients of K_T and K_R correlate not only with strength property of rock such as fracture toughness and uniaxial compressive strength, but also with the stiffness property of rock. The coefficient K_L depends exclusively on the fracture toughness of rock These results do not conflict with those obtained from laboratory experiments using linear cutting rigs.

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