The Contractor submitted a claim to the Employer for the compensation of losses suffered due to changes of ground conditions during the construction of a water works supply tunnel in Hong Kong. It took 12 years for the settlement of this claim, since this claim was so debatable and had been disputed in various courts and even at the Judicial Committee of the Privy Council U. K.
The actual ground conditions of this tunnel were completely different from the original anticipation made by the Consultant, and the quantities of steel rib support and concrete lining increased by 73 times and 7 times respectively. Therefore a construction period 2 times longer than the anticipated was required, and the Contractor filed the claim to the Employer for the additional cost of machinery depreciation, site expenses, overhead etc. which was incurred during the extended construction period.

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In this paper, it is compared the real geological section observed after excavation with geological section which three geologists prepared each other by using the same results of boring test. As a result, it is recognized that geological section is obviously different among the geologists, and is depended on the arrangement and number of boreholes. Further, a few points of view are suggesuted to provide geological section of high quality and to use geological section efficiently to desigh or construction.

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Recently, fatigue damage of steel road bridges is reported, and their design method is going to shift from the allowable stress design method to the ultimate-strength design method. For this investigation, it is necessary to understand the actual characteristics of the traffic load accurately. This paper has made clear the characteristics of traffic lane and classified vehicle to a line of traffic, respectively, as a result of analyzing a long term calculation of Tomei Expressway data from load cells.

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Large-scale civil engineering works for Dams or Earthwork cover a wide work area, various kinds of work are executed everywhere in parallel at the same time, the job sites are at a distance from the office, etc., so that lack of smooth communications occurs frequently.
This paper looks to the point of view of better efficiency and a higher level for the construction-management, it proposes a new information communication network system for such large-scale work sites, and it reports in regard to evaluation of the sysytem through introduction to actual sites and operation there, as well as problems related to this.

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Standard support patterns are not always selected according to in-situ rock condition estimated from tunnel face observation in hard rock tunnel. First, we define rock mass rating about tunnel face. The purpose of this paper is approach to make clear the relation among rock mass rating defined here, standard support patterns and some assisting methods about each tunnel face. Therefore, we show them graphically from a viewpoint of time series. As the result, it is realized that the distribution characteristic of rock mass rating is able to explain from a process of support pattern change and the number of assisting methods adopted.

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For expeditious and large construction of antiwashout underwater concrete such as the foundation of main towers of the Akashi Kaikyo Bridge, it is important to understand the condition of confluence and horizontal joints due to the pouring of concrete.
In this study, the effect of material composition and the placing method of long-scale pouring has been examined in addition to implementing large-scale experiments based on the results of the examination. As a result, the experiments confirmed the results of the examination.
Thus, it was made clear that a large and rapid construction of antiwashout underwater concrete can be constructed by using adequate materials, mix and placing and treatment of horizontal joints.

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A snow-melting system using groundwater was developed in order to save groundwater. This development was consisted of the following four devices: (1) Snow on a sidewalk was melt by flowing groundwater through pipes in the pavement and then snow on the roadway was melt by sprinkling used water flowed out from exit of pipes in the side walk. (2) Precast concrete panels which contained a pipe and had high thermal conductivity were installed in the sidewalk. (3) Water was sprinkled equally on the roadway by sprinklers. (4) Snow-melting system was controlled by a snow cover sensor. Field experiments showed that those devices were effective and some calculated results agreed with facts.

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Recently, it is reported that horizontal cracks have been found in web plates just under the vertical stiffeners which are placed in the crossings of the intermediate floor beams and outside stringers of a steel truss bridge. This cause is investigated by focusing on the occurrence of out-of-plane secondary stress due to the difference of axial thrust between the stringers using the numerical analysis, and it is pointed out that a present rehabilitated case for this damage probably can not prevent the relapse of fatigue crack. Finally, some suggestions to decrease the out-of-plane secondary stress in the web plate of floor beam are described.

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To investigate the utilization of crosshole exploration using high frequency seismic wave, several in-situ measurements were carried out to clarify the rock conditions that civil engineers face in underground construction sites. As the results, the followings were concluded. (1) Measurements using high frequency seismic wave revealed good reappearance and precision. (2) Rock classification, estimation of rock damage by excavation and rock improvement by grouting were evaluated by measuring the primary wave velocity and attenuation. (3) Informations from the repeatedly measured wave velocity and attenuation were used effectively to monitor the construction process.

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For excavated ground which has been treated with brittle materials, an analysis of the behavior of the earth-retaining structures according to the conventional ground spring method may result in underestimation and the result should be treated with caution as the residual strength is substantially smaller than the peak strength.
This paper proposes a new approach which is able to reflect the strength characteristics of the treated ground, and confirms its apricability through a comparison with the field measured value. Also proposed in this paper is a method to check the thickness of the treated ground

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A back-filling method has been developed, which uses, as a refilling material in the field, the most-difficult-to-handle excess slurry produced from the slurry shield method. A solidifying agent is added to the excess slurry to obtain a viscous fluid, which is then transported for back-filling. This report describes the various experiments necessary to implement this method in the actual work and the results of trial applications based on the experimental result. This method can reduce to a minimum the transfer of excess slurry to the outside and the consumption of pit sand for back-filling, thereby contributing to the conservation of the natural environment.

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This paper aims to estimate both the amount of excavation of a newly developed rock mass surface excavator and the wear life of cutter bits. Several excavation and wear tests of the cutter bits have been executed in-situ on the surface rock mass of grano-porphyry and rhyorite tuff. As a result, it is clarified that the amount of rock mass excavation per hour depends on the coefficient of crack of rock mass and the wear life of cutter bits depends mainly on the index of rock mass strength for wear of cutter bit and the maximum excavation torque of the rotary cutter drum. To elongate the wear life of cutter bits, some fuzzy control system of the depth or the speed of excavation should be introduced to prevent the occurrence of an excessive excavation torque.

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It is well known that damping characteristics are one of the most significant factors for aerodynamic stability of bridge structures, but few investigations have been made mostly due to lack of data.
In this study, coulomb friction force at movable supports is considered among various damping factors in order to get some informations for the damping characteristics of bridge structures. The numerical analyses based on the complex eigenvalue calculations are performed for several bridge models, paying attention to structural design factors. From these calculation results, some useful informations for the damping characteristics of bridge structures at movable supports are obtained.

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