[in Japanese]

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High fluidity concrete was applied for sandwich composite structure of immersed tunnel elements.
This work requires inspection method for self-compactability of concrete and reliable techniques for concrete filling into the steel-shells of sandwich composite structure, because of difficulty to monitor placed concrete. The authors tried to study them on full-scale models. As a result, the authors confirmed self-compactability of oncrete and selected concreting method to increase the degree of filling. Then the authors selected the method combining the radioisotope method by γ ray to measure depth of air void, and a hammer test to estimate distribution of air voids.

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The cutting of rubber for construction machinery occurs often due to crushed stones. The objective of the present paper is to investigate the cutting mechanism of rubber. The static and dynamic cutting tests for five kinds of rubber specimens were executed using several model cutting edges.
As a result, it is clarified that the static cutting begins when the penetration depth reaches about 75% thickness of rubber. SBR rubber has the superior property for the dynamic cutting resistance. NR/SBR rubber has the well-balanced properties for both the cutting and abrasive wear resistances.

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Various kinds of plug flow mixing method which is developed to mix dredged soil with cement during soil conveying work by plug flow have been invented. The discharging distance experienced, however, was only limited to several hundred meters. Recently, a long distance discharging work of approximately one km with three kinds of plug flow mixing method have been conducted to confirm applicability of this method for soil disposal on land at Fushiki-toyama port.
This paper presents technical particulars including unconfined compression strength of the cement mixed soil of the work.

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In this paper, the authors made three proposals for effective design (application of steel sections to main beams, adoption of rounded corners and utilization of secondary linings) for rectangular steel segments. Reference was also made to some consideratons during the actual design of rounded corners and to the cost involved. Then the design concept, verification tests, application to actual construction and measurement results are described.

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Groundwater leakage in shield tunneling causes deterioration of not only the tunnel but also the surrounding earth formation. Therefore, groundwater leakage is an important question when tunnels are considered in view of their durability though the leakage maintenance requires an investment of money. Because the water leakage occurs at segment joints in most cases, a selection of segment sealing materials plays an important part in tunnel waterproofing. So far, the selection of the seals, forms and measurements has been determined by experience and actual results. Thus, design for the waterproofing is yet to be standardized. In this report, various waterproofing tests using hydrotite seals which are most widely used are presented. Based on the test results, a proposal of the waterproofing design based on packing principles is also presented in this report.

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Prestressed concrete railway bridges (PCR bridges) cross rivers, roads and railways. As many PCR bridges have been constructed, the problems of durability such as deterioration of concrete and reinforcing steel bars will come to the fore after this type of bridge has been in operation for a long time.
This paper describes the evaluation of the durability of 28 technically characteristic PCR bridges operated for more than 20 years. The author evaluated the degree of durability by visual observation using the durability point proposed by the author in accordance with the “Proposed recommendation on durability design for concrete structures” published by JSCE.

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The aim of this paper is to evaluate the effect of plane load of a tracked vehicle mounted with a horizontal oscillator on the vibro-compaction of a high lifted decomposed granite soil. The vibro-compaction test was executed in a large soil bin of length of 540cm, width of 150cm and height 100cm using a small tracked vehicle of total weight of 10.9kN mounted with a horizontal oscillator having a constant exciting force of 9.8kN in the range of frequency of 16 to 51Hz. As a result, it was observed that the amount of depression of ground surface and the distribution of dry density of soil showed the maximum value respectively, at the frequency of 16Hz. The dry density at the middle stratum showed a comparatively high value due to the dilatancy effect accompaning with an occurrence of alternative shear stress, while the dry density decreased rapidly to the low constant value at the deep stratum.

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The authors devised “Wing Segments” which can reduce the cost of segmental lining by simplifying the joint structure. In this paper, full-scale loading tests were conducted to confirm the strength and rigidity of the wing segment joint and ring, and behavior of the joint was simulated by the theory model. As the results, it was confirmed that segmental rings assembled in a straight joint pattern had much the same strength and rigidity as the rings composed of ordinary segments assembled in a staggered joint pattern. Comparing with the ordinary segments, “Wing Segments” could have larger width and make the joint structure more simple. And the theory model was suitable because analytical simulations were shown the same inclination to experimental results.

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In this study work efficiency and safety under low-frequency horizontal motions in construction of bridge pylons was experimentally investigated by originally devised linear accelerator. The critical acceleration of straight line drawing, welding work, and holding of human standing posture were studied in the experiments. From the experimental results, it was found that the critical acceleration of straight line drawing, welding work, and holding of human standing posture was increased with increase in frequency which range was from 0.5 to 2.0Hz, but the critical acceleration of straight line drawing and welding work was decreased with increase in frequency under 0.5Hz. It shows different tendencies from international standard ISO6897.

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Methods to transport dredged soft mud in high density using compressed air in port construction works has some merits as minimizing volume of soil disposal area required and has potential to reduce total cost of disposal of soft mud. However, it is urgently needed to establish suitable and rational design method of such transport system because presently the design is conducted based almost on the past experiences.
In this report, the authors proposed the method to predict the state of flow of soft mud with compressed air based upon fluidity characteristics of the mud to establish suitable design method. The predicted results were studied comparatively with the data of actual plants and verify the validity of the prediction method.

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For design and construction of structures, it is required to get various geotechnical data on foundation. Generally, investigations using boring are done, and geotechinical characterizations of foundation are obtained at boring spots. As the number of boring is restricted for reasons cost and time, it is very hard to estimate the spatial distribution of geotechnical characterizations using such a few of boring data. Various spatial estimation techniques have been developed and examined. However, no efficient and convenient one has been developed. In this study, an efficient and convenient spatial estimation method is proposed using a new algorithm improved the SOM. The efficiency is shown by an example such that this proposed method is applied to a spatial estimation of permeability of bedrock.

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In this paper, the damping characteristics of Nielsen-Lohse bridge is discussed based on the energy evaluation method. The damping values of Nielsen-Lohse bridge with a span length of 236m are analyzed to grasp the contribution of dissipation energy from diagonal suspender ropes. The numerical analyses are also performed by using full scale measurements of the Aki bridge to identify the loss factor of the diagonal suspender ropes. From these calculation results, some pieces of useful information for the damping characteristics are obtained to investigate the aerodynamic stability of Nielsen-Lohse bridges.

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Recently the concept of performance—based system has been rapidly introduced in building engineering. But in civil engineering only a few attempts of this system have just begun. On this background this paper presents the basic study on the concept of performance—based system and some patterns of introducing this new system which are all vitally necessary to be clarified when the new system gets to prevail in civil engineering. Although this study comes from one of the Technology Development Projects of Ministry of Construction, the contents of this paper is attributed not to the Ministry but to the author himself

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A simulation method was developed to investigate the possibility of economical adaptation of ordinary machinery to the work on fresh concrete by changing only track shape ratio. The simulation is then verified by an experiment on a model vehicle running on fresh concrete of slump of 5.5cm with different traction force and with steering ratio of 1.6. Using the simulation, the influence of the track shape ratio on turning characteristics of tracked vehicle was investigated. The result of the investigation shows that, for a typical turning motion, the effective tractive effort decreases while the turning radius and turning moment increases with the increment of the track shape ratio.

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