Osaka Municipal Subway Line No. 7 Osaka Business Park Station has been constructed by a slurry type triple circular face shield machine. In order to propose a basic operational manual of the machine and evaluate a driving control method, two model tests and analysis of actual data under construction have been conducted. This paper presents the moving characteristics of the machine and finding obtaines through the actual construction.

View full abstract

Recently, non-circular tunneling shields are being developed, and part of the research has focused on rectangular shields. After preliminary testing involving excavation and simultaneous grouting, a full-scale prototype fabrication and tunneling tests in actual ground were conducted. This trial operation was designed to solve the problems such as cutting face stability, steering, bearing load, curve tunneling, and assembling rectangular segments. This research confirmed the viability of the technique, and produced some interesting results concerning, for example, controlling rolling using deflection jacks, loads on the cutting heads, curve tunneling, and good flexibility to ground deformations.

View full abstract

Second District Port Construction Bureau, Ministry of Transport has been working on the Tokyo Internationl Airport Offshore Expansion Project since 1984 to expand and move the airport facilities onto an offshore waste-filled island. The New C-runway, the main facility of the airport, is expected to complete in March 1997. The construction site was extremely soft ground that had been reclaimed with dredged soil and construction wastes. It appears that the underground water will remain high level in the future, and also it is expected that the maximum residual settlement 50 years after will amount to 1.5m. To cope with these problems, we made a fully worked-out design and construction works for this runway.

View full abstract

In the small-diameter pipe excavation-thrust method, the judgement in the operation is dependent on the experience of skilled operators. Therefore, it is necessary to improve the control system and to examine the auto steering control method. The purposes of this study are, to propose a simple analysis model according to direction control mechanism, to compare this analysis model with system identification for time-series model and to examine on accuracy the auto steering control methods, the sequence, the fuzzy, and the neural network driven fuzzy controls by means of the simulation.

View full abstract

It has been pointed out that the applicable maximum depth of Plastic Board Drain (PD), which is used for accelerating the dissipation of the pore water pressure in soft clay, is about 20m because of its small sectional area. The authors have developed a large section band shaped drain applied for deeper soil improvement. Filter and core of this PD are composed of high strength polyester textiles and high strength vinyl chloride respectively, to resist the large earth pressure. It was found that the transmitibility of this PD can be secured to 20cm³/sec under a confining pressure of 490kPa and apparent axial strain of 50%. Furthermore, the equivalent diameter of the PD was found to be 4.0-6.0cm under high pressure.

View full abstract

This dissertation specifically refers to inground LNG storage tanks and studies methods to achieve a more efficient and streamlined design for the reinforced concrete structures required for these storage facilities. Studies have been carried out with the limit state design method used for this purpose. The results of these investigations have led to the development of specific design methods which are capable of achieving the two goals of improving the reliability of equipment safety and of improving the economic efficiency of construction at the same time. The limit state design method has been proved very effective system for streamlining in design on the basis of the leadership of the engineering staff in control.

View full abstract

Recently, the necessity of developing a practical bridge management system has been pointed out because the maintenance of bridges, a key element of the highway networks, has become a major social concern. This paper describes a newly developed bridge management system (BMS) for deteriorating concrete bridges taking advantage of the output from a concrete bridge rating expert system which is currently being developed. Furthermore, a few numerical examples for some existing concrete bridges are presented so as to demonstrate the suitability of the proposed bridge management system based on lifetime cost minimization approach.

View full abstract

The beam-column method is usually applied to retaining wall design. But, there are some cases that prediction by using this method doesn't simulate the trend observed by the in-situ measurements, because the procedure for determining computational parameters is not well defined.
In this paper, we performed the back analysis by using the measurement data during excavation work at 10 construction site in Osaka, and estimated the lateral pressure acted on the wall and coefficient of subgrade reaction that is input parameters of the beam-column method. As a result it was found that the lateral pressure and coefficient of subgrade reaction depend on displacement of retaining wall.

View full abstract

At present, slurry discharged from the construction sites are disposed in many cases since there is no suitable treatment method to improve the slurry and this has caused some problems to the environment. From that viewpoint, the authors have developed a new divice to dewater slurry under low pressure and vacuum. The treatment system together with the dehydrator has been introduced in the shield construction in practice. This paper discussed the components and functions of the dehydrator and the experimental results conducted on the site. The system can dewater the slurry with high efficiency. Further the treated sludge cage with certain stiffness can be reused with additional of cement as flocculants.

View full abstract

To clarify the impact cutting productivity of mortar by a point attack bit, a new rotary impact cutting test machine was developed. The purpose of this study is to consider experimentally the effect of the cutting pitch, the cutting depth and the circumferential speed of the point attack bit on the cutting torque and the cutting volume of mortar. As the result, it is verified that the maximum torque acting on the cutting drum and the horizontal maximum impact acceleration increase with the increment of the cutting pitch and the circumferential speed of the point attack bit, and the cutting productivity takes a maximum value at some value of the cutting pitch for all cutting depth.

View full abstract

An investigation was carried out to measure, identify, and analyze deformational behaviour of a concrete lining of a tunnel reservoir excavated by NATM, subject to the first water pouring. The measurement results showed that moisture was transferred into concrete through the layer of surface coating. To identify the extent of expansion due to moisture transfer, back analysis was performed considering all the factors affecting the deformation of concrete lining. The results showed that the magnitude of strain caused by moisture-induced expansion surpassed by far that caused by water pressure and was the main factor controlling the deformational behaviour of the concrete lining.

View full abstract

Now that Japan's period of rapid economic growth is over and markets are becoming more global, change is being forced on the systems by which the Japanese construction market operates and on construction companies themselves. In particular, many predict that project delivery systems will become more diverse as the construction market internationalizes. Taking the position that there are advantages to the Management Contract system—which is already well-established in the U. S. and advanced European countries—this paper compares this contracting system with the Work Contract system and identifies its possible benefits to Japan.

View full abstract