One of the world largest in-ground LNG tanks with the capacity of 200, 000KL is being constructed in Midorihama-cho, Chita City, Aichi Prefecture. The construction site is a reclaimed area underlain by the sedimentary soft rocks (Tokoname Group) of the Tertiary age. With the progress of the soil excavation inside the diaphragm-wall, an oval deformation with NE-SW compression was observed in the diaphragm-wall. From the geological study, it is concluded that the deformation was induced by the anisotropy o f the intrinsic regional stress field. To reflect on the design and construction of diaphragm-walls hereafter, the new findings, such as the method to estimate the direction of an eccentric soil pressure, are described in this paper.

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In order to establish anti-corrosive coating technologies in cold regions, exposure tests and actual bridge tests on performance not only of coating systems specified in steel bridge coating manuals, but also of ultra-thick film coating systems, including coatings for frozen sea and heavy-duty anti-corrosive paints developed for cold regions, were conducted. The results of 10-year exposure tests and 8-year actual bridge tests showed that a coating system in which zinc-rich paints were used as primer and epoxy+polyurethane or fluorine-contained resins were applied had excellent corrosion resistance; the ultra-thick film coating systems, if top coats with excellent weather resistance were applied, is promising as a heavy-duty anti-corrosive coating system; and phthalic and chlorinated rubber paints were unsuited for cold regions because clacking and peeling occurred at early age.

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Many electrical leak detection methods have been researched and developed, in many laboratories, for landfill site lined with geomembrane such as synthetic rubber and plastics. The methods assume that the geomembrane has a high electrical resistance and the points of leakage are searched out and detected by mesuring differences in electrical potential, current or electrical resistivity. The authors of this paper have investigated the electrical properties of various membranes, and have found that some geomembranes are not electrical insulators and therefore the traditional theory that they should be insulators no longer holds good. This paper presents the electrical structure within a landfill site, the electrical properties of various geomembranes and the influence of geomembranes with a low electrical resistivity on electrical leak detection.

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In order to control the behavior of multi-faced shield tunneling machine, it is of great importance to estimate accurately the movement of the machine during the excavation. An estimation model for posture change was proposed based on the equilibrium of force and moment acted against the shield tunnelling machine. Two series of shield excavation tests were carried out on site; one for determining parameters of the model, and the other for verifying the model by comparing the prediction value from the model with the test one. As a result, it was certified that the proposed model could give reasonable posture change estimation.

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Recent airports are inevitably constructed on deep water areas or reclaimed land over very weak grounds as seen in the Kansai International Airport and the Tokyo International Airport.This is why countermeasures for ground subsidence have become an important issue. The level measurement is important for ensuring safe aircraft operations and maintaining airport facilities, as can be seen at the Tokyo International Airport. But the current surveys are conducted using levels and total stations. It is difficult to improve work efficiencies using this method. That is why the development of efficient measuring instruments has been required. We developed a new height measurement system combining RTK-GPS and laser level, and demonstrated the accuracy and efficiency of its potential application.

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Conventionally, in-situ permeability test by single-hole is employed to obtain the coefficient of permeability for sandy ground. However, it becomes difficult to apply this conventional method due to the complication of present construction projects, such as very deep location, short testing time afforded and use of mud drilling. Although only to clayey ground because of head loss in the system, BAT system, developed by B. A. Torstenssen, Sweden, can be basically applied to overcome these limitations presently. In this study, we improved BAT system and developed how to minimize the head loss on the basis of the fact that head loss is closely related to the velocity of groundwater flow inside the system in order to apply BAT system to sandy ground.

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The objective of this study is to propose a strategy for the application of the slope stability evaluation models for risk prevention plans. One of the difficulties is to interpret the prediction results derived from “different models”. In this contribution, four prediction models were considered: (1) a Bayesian probability model, (2) a Certainty factor model, (3) a Fuzzy set theory mode, and (4) a SSE model based on the quantification method of Type-II. As the results, it is indicated that: (a) the “SSE model” and “Fuzzy set theory model” are particularly effective for evaluating the hazardous area in the study area; and (b) as a final product, “Risky-side” and “Safe-side” assessment sub-areas are delineated from the difference map (termed “DIF-map”) made by those selected two models.

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