The time for one complete cycle of diaphragm wall excavation by hydraulic bucket was monitored using a special video camera and determined statistically.
A theoretical analysis of the excavation by hydraulic bucket as a variable exacavation problems was also done.
Combining the monitored results and theoretical analysis an estimatin method of the efficiency of diaphragm wall excavation has been proposed.

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The third stage development area of Tokyo International Airport Extension Project is required to undergo soil stabilization by sand drain immediately after its reclamation by dredged clay of high water content. The centrifuge loading tests were conducted to check the satability of sand drains during driving and under embankment loading, and the necessity of using fabri-packed sand drains i. e. wrapping of geotextile envelopes, in such a clay was clarified. In this study the critical driving length of fabri-packed sand drains and the tensile strength of wrapping material against compression and bending of sand drains were investigated. As a result it was confirmed that the method can be used under practically estimated construction conditions without rapture of wrapping material securing the continuity of sand drain and consequently the method is adopted for the present area.

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The dependence of fine aggregate of concrete structures on sea sand increases in the western part of Japan. Both the sea-sand mining and the decrease of sand supply from the rivers may accelerate beach erosion and devastate the coastal environment. The change of longshore current due to man-made coastal structures, the decrease of sand supply from rivers, the frequent occurrence of storms, the sea-sand mining, etc. have been examined as causes of this erosion. However, what are the most essential causes still has not been revealed. The purposes of this paper are to investigate the present situation of sea-sand mining in seventeen prefectures of the western part of Japan and to examine its influence on the coastal environment.

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In Long-span prestressed concrete bridges (box girder or cable stayed bridge), the design and construction control become increasingly complex as construction proceeds with step by step process.
This paper presents the method and operation of an automatic levelling module by CCD camera and the experimental results by this system.
Successful application of the system showed the system would be an effective and efficient construction aid.

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Based on the actual results of the work, this paper has made clear characteristics of restrained settlement of the ground surface by using vertical earth stitching bolts and their effect for tunnel excavation under the ground condition of loose bedsand and shallow covering.
Considering the geology of the site consists of filling and alluvial deposit, the settlement restraint method by vertical stitching earth bolts can be widely applied to tunnel construction in urban area.

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Tn order to evaluate the applicability of a new band-shaped horizontal drain sandwitches by two types of geotextile on the seabed, a series of large scale laboratory consolidation tests and field tests were performed. Followings are the findings from the present study. Mud cake which may be accumulated between vertical and horizontal drain has almost no influence on consolidation efficiency. And also field tests using weight bags to set the horizontal drain on the seabed yield good results.

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This paper introduces an interim design, fabrication and erection code for composite slab with truss-typed shear connectors. This composite slab was recently developed. A series of the tests were conducted in order to evaluating
(1) the strength of shear connector itself; (2) the ultimate strength; and, (3) the fatigue strength and durability of this composite slab under fixed loading point and moving load. Additionally the Wakihama bridge has newly constructed for test case.

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The Waterworks Bureau of ToKyo Metropolitan goverment applied newly developed mechanical shield docking method for the construction of water pipes.
This method allows shield docking works without any auxiliary works. The construction work completed successfully.
This paper outlines the process of adopting of the above new docking method and the construction work which represents such kind of construction for the first time in the world, with some views.

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This experimental study has been carried out in order to investigate the durability of artificial soft rock which were made by clay pulverized natural mud-rock, natural sand, water and new blended blast-furnace slag cement mixtures.
In the experiment, the artificial soft rock specimens were exposed in some curing conditions such as in curing rooms at 5-40°C in order to eliminate the temperature effect, in some water conditions and in some weathering conditions in order to eliminate the resistance against the actions of various ground water and weathering for about 10 years. These studies proved that the artificial soft rock have high resistance against the actions of various ground water and weathering.
The long-term durability of them were also verified by the results of the follow-up investigations, after exposuring in field for 10 years.

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Collapses of cutting faces are reported to have occurred during tunneling by the slurry shield method in sand beds of a uniform particle size with a low proportion of fine particles and in gravel beds with high permeability. The authors conducted laboratory tests and experiments, assuming tunneling in a highly permeable gravel bed, in order to define the optimum properties of suspension for this tunneling method. The tests/experiments included physical property tests on suspension, slurry seepage tests, and slurry trap door experiments. From the dehydration amounts obtained in the slurry seepage tests, the authors propose a real time tunneling control method by deviation of the slurry flow balance, and verify the effectiveness of this method by applying it to the excavation of a large-section shield tunnel.

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Novel roadbed that laminates one lime-fly ash layer between two sand layers, i. e. laminated roadbed and the roadbed replaced with sand were executed as preventive measures against mud-pumping. And after the execution, various long term observations were carried out to investigate the effect of improvement as produced by these preventive measures. In addition, numerical calculations considering maturity expressed by temperature and elapsed day were performed to evaluate the influence of temperature on coefficients of subgrade reaction of laminated roadbed.
It was found that laminated roadbed had enough stability against train load and the tendency in increasing was clearly different by time of execution, although the calculated bearing capacity of laminated roadbed increased with elapsed day.

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For the safe and economical construction of tunnels in the extremely complex and diverse geological conditions which prevail in Japan, it is essential to perform in the construction stage detailed and rational observation, measurement and analysis of ground behavior, and reflect the results back into design and construction. The New Three-Dimensional Measuring and Analysis System for Tunneling was developed as a system to perform this “data based construction execution” satisfactorily. This system is composed of two subsystems; a three-dimensional measurement instrument to collect measurement data accurately and swiftly, and a data processing system to analyses this data so that it can be utilized effectively.

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