Kazuyoshi Tateyama

The Evaluation of Ground Properties and its Application to the Automatic Control of Vibratory Soil Compactors

A ground-evaluating method was suggested which makes use of the behaviour of an exciter that vibrates on the ground. Numerical simulations were carried out to investigate the relationship among the vibrating behaviour of the exciter, the ground stiffness and the vibrating conditions of the exciter, -A method that evalu ates the :groundstiffness with the vibrating behaviour of any. exciter was derived from the rests of the numerical simulations. The applicability of this method was examined by field experiments and its application to the automatic control of a vibratory soil compactor was discussed.

EXPERIMENTAL RESEARCH ON BEHAVIOR OF SOIL PARTICLES IN OSCILLATORY FEILDS

振動場における粒状材料の振動挙動とそれに与える振動条件や地盤条件の影響を解明する研究の一環として，室内振動実験を行った．実験では，粒子の接触状況を電気伝導を利用して測定する手法を採用した．この手法は，導電性を有する粒状体で供試体を作成し，これに振動を加えた際の供試体中の電気抵抗の変化を計測する手法である．粒子間の接触状況に応じて供試体の電気抵抗が変化するため，振動場における粒状体の挙動を把握することができる．実験結果を振動加速度，粒径の違いによって比較したところ，加速度が一定であれば振動数を変化させるより振幅を変化させるほうが，粒子のかみ合わせが外れ，粒子の相互移動が起こり易いということがわかった．また，粒子のかみ合わせの外れ易さは，粒子の粒径と振幅の比に依存することが明らかになった．

Energy reduction by optimization in loading process for soil materials

土質材料を圧縮や破壊させるために必要なエネルギーは，対象とする土質物性と，載荷応力や変位の時刻履歴である載荷過程に依存する。したがって切盛土工事においては，対象土の物性情報を反映して建設機械による作業時の力の加え方である載荷過程を工夫することで，より少ない消費エネルギーで作業が可能と考えられる。そこで，本論文では最小の消費エネルギーで所定の圧縮や破壊が可能な載荷過程について基礎的な研究を行った。まず，最小の消費エネルギーで圧縮可能な載荷過程を，飽和した粘性土を対象としてTerzaghiの一次元圧密理論をもとに求め，室内試験により有用性を確認した。次に，セメント固化土に対して載荷速度の異なる一軸圧縮状態での破壊試験を実施して，載荷速度の影響を表わす数値モデルを構築した。その数値モデルに対して様々な載荷過程のシミュレーションを行い，最小の消費エネルギーで破壊可能な載荷過程を求めた。

Precision Construction in Japan - Utilization of Information and Communication Technology

Various information and communication technologies have been introduced to conventional construction methodologies to make them more advanced. Although these advanced methodologies are often referred to as “Intelligent construction” or “Smart construction” in Japan, we call them “Precision construction” here to make their purpose clearer. Precision construction generally has two different functions. One is to support machine control and the other is to support the flexible decision making of the on-site engineers. This paper introduces the present conditions and the foresight of precision construction in Japan.

Experimental research on the behavior of soil particles in an oscillatory field

The subsidence of the ground during an earthquake is often understood to be a phenomenon induced by liquefaction. However, it is possible for subsidence to occur even in an unsaturated ground without the increase in excess pore water pressure. It is thought to be induced by the shake packing of soil particles due to the oscillatory load during the earthquake. In the present study, we examine the behavior of soil particles in an oscillatory field through model tests and a numerical simulation, and discuss the relationship among the shake packing behavior, vibrating conditions such as frequency and amplitude, and soil particle size. In the model tests, we employ particles of coke as the model for the soil particles. Coke carries electricity and the electric resistance of the coke particles depends on the tangency among the particles. In the numerical simulation, we employ the two‐dimensional distinct element method (DEM). DEM is the method used to trace the movement of the particles within a short time inte...

Underground Space Construction by Explosive Loading in a Borehole

In cases where a borehole has been dug in the ground and subjected to an explosive load, the soil around the borehole wall will be abruptly compressed and a cavity will then be created in the portion of the ground that is surrounded by the compressed soil wall. When this procedure is applied to the construction of tunnels or foundations, underground spaces can be created with minimum mucking and a thinner lining. The authors carried out some laboratory experiments in which small boreholes were expanded by blasting. The results of the experiments increase our knowledge and elevate the possibility of applying this procedure to underground space construction.

EFFECT OF WATER ABSORPTION BY ROOTS OF PLANTS ON THE SUCTION IN UNSATURATED GROUND

人工法面に対し安定性の向上を目的として緑化が行われるケースが増えている. 植物の根系が法面の安定に及ぼす影響のうち, ここでは, 根系が地盤中から水分を吸収することによって地盤内のサクションの増加に寄与する効果について調べるため, テンシオメーターを用いた原位置計測を行った. この結果, 降雨後における地盤内のサクションの回復に根系の吸水活動が大きな役割を果たすことが明らかになり, また, この効果の季節や時間帯, さらには樹木の種類による差異等に関しても新たな知見を得た.

Evaluation of Ground Properties in Deep Soil Improvement Method and its Application to Construction Automatization

As one of the studies on automatization in the deep soil improvement method, theoretical and experimental studies were carried out to develop a method to estimate soil properties in real-time during construction. In the theoretical study, the resistance acting on the improving machines from the ground was studied with soil cutting theory, and the relationship among the resistance and the ground properties was discussed The results of the theoretical study were examined through field experiments, and a method was suggested for evaluating the values of the SPT of the ground the N values, from information on the resistance acting on the machines from the ground Applications of this soil-estimating method to automatization in the deep soil improvement method were discussed through the determination of the best operating method for the DJM machine according to the soil properties estimated by the suggested method.

WEAR CHARACTERISTICS OF RUBBER MATERIAL AND ITS APPLICATION TO THE PREDICTION OF WEAR LIFE OF TRACK BELT ON ROUGH TERRAIN

ブルドーザの履帯用ゴム材の摩耗特性を解明するため, 代表的な耐摩耗ゴムからなる試験片に対して砂岩からなる砕石路面における摩耗試験を行った. ここではゴム材の摩耗特性に及ぼすゴムの材質, 接地圧, 摩耗に関する雰囲気 (乾燥, 水浸), ならびに路面粗さの影響について考察を加えた. さらに, この結果を利用してブルドーザのゴム履帯の摩耗寿命予測を行う手法を提案した.

A CONSIDERATION FOR IMPACT COMPACTION OF SANDY SEA BED

衝撃締固めを受ける水浸状態の砂地盤の締固め特性を一連の突固め実験により明らかにした. 実験条件としてはランマの落下回数, 落下高さ, 重量, 底面積を変化させた. 比較のために気乾砂に対する同様な実験を実施した. 各実験条件および締固めエネルギーと砂の締固め密度との関係を調べた. 気乾砂ではほぼ投入した締固めエネルギーに見合った締固め効果が得られるのに対し, 水浸砂では締固めエネルギーよりはランマの落下高さなどの実験条件の影響を強く受けることが判明した.