[in Japanese]

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The ultimate purpose of this study is to establish the criterion of falling from concrete lining of road tunnel. As the fundamental data for such criterion, this paper presents the shear strength of cracked concrete in tunnel lining. The shearing test by employing core specimens in actual road tunnel was conducted for obtaining the fundamental properties of concrete falling. Shear stresses of cracked core specimen were affected by roughness of cross-section and axial force. And shear strengths between cracked sections were 1-3N/mm².

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To evaluate the effect of frequency of tracked vehicle mounted with a vertical oscillator on the vibro-compaction of a high lifted decomposed granite soil of 45cm depth, a model experiment was executed using a large soil bin at a frequency 5-35Hz, setting the load ratio of vehicle weight 4.9kN to the maximum oscillating force to be firm 0.2 to 2.0. Consequently the optimum frequency to maximize the effect of compaction increases with the increase of the number of compaction. It was observed that the optimum frequency is 10.2±2.7Hz respectively, for the load ratios 1.0. For an actual tracked vehicle of 47.0kN weight and high-lifted stratum of 90cm, it was estimated that the degree of compaction, for an example, at a load ratio of 2.0 and a frequency of 16Hz reaches to be more than 90% at the bottom stratum.

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For level 2 design earthquakes, shear properties of the reinforced concrete sidewall of the excavation portion in the U-type cross section of the existing tunnel is studied. The cross-sectional forces are calculated by dynamic response analysis considering material non-linearity. Calculation results show the destructive mode at side wall is shear type, and shear reinforcement is required to increase shear strength of the wall
However, there is no appropriate counter measure about how to reinforce these structures. Therefore we propose the new reinforcement method by SHEAR STEEL RODS EMBEDDING. Holes are drilled at the sidewall, the steel rods are put in and embed with fixate. Static monotolic loading tests and reversal cyclic loading tests verify the efficiency of the embed steel rods for shear reinforcement.

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Rinkai Oimachi station was constructed by removing part of segments of shield tunnel and excavate the soil between tunnel and the adjacent shaft. As the lower tunnel was located in the Tokyo gravel layer which pore water pressure was greater than 300kN/m², cutoff measure for this layer was the key for the safety construction. Chemical grouting was adopted due to the restriction of construction period. The grouting work was planned in three steps, first, second and complementary grouting. Resistivity tomography and so on were carried out to confirm the effect. The result was satisfactory and the volume of complementary grouting was less than 1/10 of first one. In addition, deep well was performed to reduce the risk of leakage and safety construction was achieved.

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An in-situ compaction with inner mold system is one of the methods of buffer construction technology. The method is examined in this study by carrying out compaction tests, and validated with real-size disposal pit made of concrete and semi-automatic compaction machine designed for work with remote controlled system. In this study, basic performance of in-situ compaction machine with inner mold was confirmed as mechanically feasibility, and it was also confirmed that compaction buffer has an appropriate dry density of more than 1.6Mg/m³ toward a required specification of engineered barrier system. Finally, it is concluded that the technology is prospective for actual construction of buffer material.

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As a construction method of grade separations with railways and highways, the method of constructing a tunnel structure by connecting steel elements that are coupled together by a bitten joint was developed. This study is for the purpose of investigating the mechanical properties of the joint. Static tension tests were conducted to quantitatively evaluate the tensile properties of the joint. Furthermore, through fatigue tests, the specific failure modes were confirmed and their experimental S-N curves were presented.

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It is a common practice for tunnel engineers, who work on squeezing rock tunnels with having the possibility of large displacement, to decide empirically countermeasures against reducing displacement, the support rank, and the tunnel construction method. However, it has not been clearly understood yet regarding to this countermeasures of displacement reduction, i.e. the quantitative evaluation, the standard of support rank, and its construction method.
This paper describes the results of analysis from the past tunnel constructions in concerned ground. The aims is that the tunnel engineers are able to handle the occurred condition of squeezing ground with grasping the information of ground condition in advance based on the viewpoints of empirical tunnel engineering.

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Field measurements were carried out on the M-pedestrian suspension bridge and it was shown that the girder vibrated either in the third asymmetric mode with a natural frequency of 0.88Hz or the fourth symmetric mode with a natural frequency of 1.02Hz. The maximum lateral displacement reached 45mm. Accelerometers attached to pedestrians showed that the pedestrians synchronized to the girder frequency with a phase of between 120 to 160 degrees ahead of the girder. According to the ambient vibrations, the synchronization is unlikely to occur at the girder frequency under 0.6Hz. Analyzing the vibration data of the three pedestrian bridges, the smaller bridge mass and damping produces the larger girder response.

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Tangential, lateral and normal forces acting on a disc cutter bit having three tip angles and amount of debris in several cutting spaces and penetration depths per round for four kinds of rock samples were measured. It was observed that the specific cutting energy, i.e. the ratio of the excavation work of the disc cutter bit to the amount of debris, showed a minimum value 0.036kNcm/cm³ for andesite at the ratio of cutting space and penetration depth per round of 52.7 for the bit of the tip angle of π/4rad. The method of edge excavation for the rock material might achieve the great efficiency of excavation of about 23 times that of plane excavation.

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The authors have been working on the development of a Maintenance Support System for Concrete Structures. This system enables people to perform structural evaluation like domain experts. Using a fuzzy hierarchical structure model based on the experience and knowledge of human experts that hierarchizes the relationships between factors of causing damage concrete structures, the system infers the damage and its cause of the target structure. In this study, an efficient making method of the hierarchical structure model was clarified by the application of this system to a real structure.

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One factor affecting the degree of attractiveness of underground spaces is “anticipation” which evokes a desire to go ahead or explore. The aim of this study is to investigate the factors contributing to such anticipation. After local field studies, overseas field studies, and the experiments, we revealed that extreme anticipation points are determined by the invisibility ratio of space and are most influenced by the cross-sectional invisibility ratio of space. Extreme anticipation points and extreme anticipation levels were also estimated.

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U-type settlement gauges have been used at many construction sites to measure swell and sink of infrastructures neighboring a construction field But this type settlement gauge has much room for improvement to prevent the precision deterioration due to a longtime atmosphere temperature change in the field.
In this study, an open-channel type settlement measurement system that can prevent the effect of temperature change was developed. It is proved to be practically useful with good measurementprecision and stability through its basic experiment indoor tests.

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Inspection is an important task to manage the maintenance of constructed facilities safely and economically for a long time. However, inspection relies on inspectors' knowledge and experience qualitatively and tends to be separated from the advanced downstream tasks in the maintenance management system. In order to integrate inspection with the maintenance system and to inherit the knowledge th m experienced inspectors to others, we have developed anon-site inspection support system consisting of RFID tags PDAs, and a PC with relational database, which can be used for a long time, and we have applied it to the actual inspection work at two existing large dams in Japan.

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In this paper, a methodology associated with evaluation of construction cost variation caused by geotechnical risk based on PFI projects was presented. In detail, this paper proposed that the volatility of cost caused by geotechnical risk is defined as variation around expected value on probabilistic distribution, which can be commonly connected to the defined volatility based on financial engineering. Furthermore, the proposed methodology was applied to evaluate cost volatility of an actual underground construction project. Finally, results made it clear that the proposed methodology is very useful for decision making process of a PFI construction project with its various participants, such as corporate manages and lenders whose major are not engineering.

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In the measurement of compressive load using load cells, it is recommended to set up the load cell on stiff and flat places, however the standard of a degree of stiffness has not been prescribed explicitly. This study investigates the influence of impedance at the setup locations on the output values of load cell through a series of knocking tests in which the tested load cells are placed at statically and dynamically stiff places, and also through a simulation technique under the application of impedance method. The results revealed that the output values of load cell are affected by the stiffness of setup locations significantly, and which mechanism can be examined in detail by the impedance method.

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A construction of twin type tunnel with center pillar, which stands very close to each other, is usual construction method in urban area, because of the limitation of the land utilization. Twin type closed tunneling method without using center pillar is advantageous in terms of work period and construction costs. However, it had never been adopted by shortage of construction experience. The authors had a construction experience the twin type tunneling method with and without using center pillar at Shimoitozu Tunnel. This paper deals with the predominancy of each construction method by comparison of results of field measurements.

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In order to satisfy the quality, three special admixtures are usually employed for quick hardening concrete in New Pre-Lining Support (New PLS) method. Such concrete has tendency of higher material cost than normal concrete. Thus, the cost optimization of the quick hardening concrete is an important subject in order to apply the New PLS method widely. The present study discussed about the cost optimization of quick hardening concrete based on various investigations and constructions.

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This study aims to make a quantitatively evaluation for total amount of direct earthquake damage loss accompanying liquefaction potential change at the Osaka City area in case of inland and plate-boundary earthquakes. The major findings are as follows; 1) The estimated total amount of direct damage loss at current ground water level reached on 9.6 trillion yen for inland earthquake and on 2.5 trillion yen for plate-boundary earthquake, respectively. 2) In case of existing water level dropped down to 3m, the decrease amount of direct damage loss will be 2.9 trillion yen and 100 billion yen, respectively. 3) In future earthquakes, management of ground water level is one of effective measures for mitigating the economical damage loss in mega-cities.

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