[in Japanese]

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A seawater pumped storage power plant with a 30 MW maximum capacity of electricity has been tested to investigate operational performance and technical problems for five years since March 1999. This paper describes some results on the strength of the fiber reinforced plastics (FRP) penstock and hydraulic losses caused by stuck oyster-shells and barnacles on penstock wall. According to those results, it is found that the FRP penstock in rock mass had the required strength against high water pressure and the hydraulic losses due to increasing roughness had been less than a designed value. The results obtained from the study will boost the realization of the seawater pumped storage power plants.

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The purpose of this report is to increase the crushing efficiency of a concrete structure by means of an edge excavation system using a ripping disc cutter bit. A cutting drum mounting a roller cutter bit and two series of ripping disc cutter bit was used for a model test using several specimens of concrete. As a result, it was observed that the maximum horizontal and vertical excavation force, and the maximum torque acting on a cutting drum and the excavation power increased with the increment of uniaxial compressive strength of concrete and depth of cutting. The specific cutting energy decreased with the increment of cutting depth in the range of high efficiency of a ripping disc cutter bit, but increased with the increment of the uniaxial strength of concrete.

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Vision metrology with a single camera is applied to slope displacement detection. A camera configuration to meet the required measurement precision, sensitivity and reliability is looked for. The paper derives related statistical expressions and compares alternative camera configurations, which can detect 2mm displacements per 30m length. Evaluation is experimentally executed by use of a 1/30 scale model of a typical construction site of a slope with an idealistc targeting condition. The configuration of four exposures at each of three stations is proved to match the three criteria above.

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In order to prevent long continuous disruptions to aquifers by cut-slope road construction, a construction method for providing a permanent drainage system combining wells and pipes was developed and applied. The features of this construction method are that it overcomes the main cause of drainage blockages, incorporates a monitoring system for performing efficient maintenance, and reduces the lowering of the water table to the greatest possible extent. We verified that the water collection function continued effectively for up to 10 years after installation.

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To prevent fatigue cracks in damaged steel bridge deck, the authors investigated a new retrofit method, in which a pseudo-stain hardening fiber reinforced cement composite, ECC, is effectively utilized as strengthening top layer on steel decks. To realize this retrofit method, experimental investigation regarding full-scale ECC production and ECC construction in site was conducted. As a result, it was demonstrated that ECC can be successfully produced using normal concrete mixing facility and processed in total area over 12,000m² on actual steel bridge deck. Completed ECC layer with 40mm thickness involved no visible shrinkage cracks.

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The safety condition of a rock-fill dam has been evaluated by comparing the data of the measurement apparatuses with results getting from numerical analyses. Being surveyed the latest trends on the predicting method, the method (mainly numerical analysis) has been highly developed. However, its method has not always reflected accurately the real movement. The object of this report is to develop a new method combining the numerical analysis, the genetic algorithm and the artificial neural network. This new method could be successfully applied to the evaluation and prediction of pore pressure change in real two rock-fill dams.

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Two types of new cable-supported bridges using pipe girders and steel orthotropic decks were proposed; two-pipe-girder bridges with two cable planes and three-pipe-girder bridges with one cable plane. The suspension bridge with a main span of 750m and the cable-stayed bridge with a main span of 500m were designed and validated to be feasible. Wind tunnel tests were then conducted for these bridges. The torsional flutter occurred at the non-dimensional wind speed of about 4.5 for the two-pipe-girder bridge, which was higher than that of the pipe girder with RC slabs. The three-pipe-girder bridge shows superb aero-dynamic properties.

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In this paper, a Weibull hazard model is presented to describe the expected life length of the tunnel lumps, and the inspection/replacement processes of tunnel lighting systems are formulated by the aggregated Markov model. The inspection/replacement intervals and the maximum life length of the lumps are considered as the major management policy variables. And the impacts of these management variables upon the life cycle costs and the fault probability of the lumps are investigated. The optimal inspection/replacement model is presented to find the optimal policy that minimizes the life cycle costs given the levels of the fault risks. The applicability of the methodologies presented in the paper is examined by a case study conducted with the data-base in the real world.

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A magnetic anisotropy sensor is used for nondestructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a nondestructive manner, which then can be translated into the absolute values of stresses existing on the surface of the material. This technique was applied to measure stresses of steel ribs, used as tunnel support structures, to confirm expected measurement accuracy. The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction of underground structures.

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Life cycle cost (LCC) is required for rational design of future infrastructure. The present study focused on LCC of pipe heating facility, which is usually employed for mountain road in snowy region. Fatigue durability of concrete slab with heating pipe was evaluated by the equation for fatigue estimation. Pipe heating in mountain road has little possibility of fatigue failure by automobile, and life of pipe heating is determined by life of pipe. LCC of pipe heating with stainless pipe is almost lower than LCC of standard method, i.e. anti-freezing agent.

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