The paper describes subjects that should be discussed and may be significant for the switch from the specification-based design scheme to the performance-based design scheme : comprehensive design codes which are code for code writers ; hierarchy of design codes ; necessity of conformity assessment of design results ; and utilization of reliability-based design to introduce new technologies. The author also indicates that internationalization of Japanese technical standards and active participation in making up international standards may contribute effectively to get overseas construction market.

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A main character of the new construction method is that box culverts constructed mutually engage elements at the joints. This study is about the closing composition of the structure constructed in this method. The closing composition has to be able to adjust an error at a regular situation of both elements and construct in a small space. According these condition, the closing one adopted reinforced concrete with a characteristic lapped joint of closed shape. And this joint is reinforced by steel-bar. This paper describes the feature, and estimates the flexural strength of a beams with this joints.

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This paper describes a seismic exploration method for investigating soil condition of Shinkansen railroad embankments. In this method, elastic waves are generated by human power, and all wave excitation points and receivers were set on the embankment slope surface. Seismic tomography was also presented with the exploration data for several railroad embankments. Since tomography results well agree with other methods, such as the down-hole PS logging conducted at the same place, this simple method is thought to be useful for the seismic survey especially in small-scale hilly topography. This method was then standardized by considering the local condition of railroad sites. Finally this method was applied to 4 sites of Shinkansen embankments, and some observations were mentioned concerning to the internal characteristics of the embankments constructed approximately 40 years ago.

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We investigated relationships between prestressing force and creep of ground anchorages executed on slopes subjected to water infiltration. This paper reported on monitoring data of anchors which were installed inside different grounds such as a road cutting slope, a storage reservoir slope and a weathered serpentinite slope. The decrease of the prestressing force could be caused by a collapse due to rainfall or submergence in an unsaturated soil ground. On the other hand, the increase of the prestressing force could be caused by swelling of an expansive clay mineral. Finally, we emphasized that the prestressing force of the anchor expected fasten effect might be not effectively applying on a slip surface.

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This paper delineates the examination of the time dependent behaviors of landslides observed at two sites by focusing on the saturation of sliding surface clays.
We also study a relationship between test conditions and actual phenomenon by conducting mechanical tests with boring cores, since we consider that mechanical characteristics of sliding surface clay give large impact on landslide speed.
In conclusion, we suggest that it is important to consider the degree of saturation of sliding surface clay as one of the reason to cause landslide on designing landslide prevention works.

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Cathodic protection has been applied widely to steel reinforcement in concrete. However, it is generally very difficult to establish optimal corrosion protection for such steel and to precisely evaluate the corrosion protection effect. We constructed the new numerical analysis technique with FEM to optimize the cathodic protection to the reinforcement steel in concrete. We constructed the precise calculation method of the potential-current distribution, which can account for ion migration, ion diffusion, the IR drop inside the anode, and the polarization phenomenon of the anode and reinforcement steel. The effects of the distance between steels and the cover layer thickness of concrete on the cathodic protection current distribution were estimated.

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In the design of tunnel linings constructed with steel fiber reinforcement concrete, the second straight-line of a two-straight-line model as a tension-softening curve is adopted in this study. The influence of tensile limit strain on the lining strength and characteristics of cracks caused by stress resultant were examined in order to obtain the lining strength and the crack width from bending test results handily and to reflect it in the lining design. As a result, the method for estimating the crack width was clarified, and the method for approximating two parameters of the tension-softening curve from a load-crack width curve obtained by a bending test was proposed.

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The authors are developing an effective design and construction system for underground rock caverns based on the monitoring of EDZ (Excavation Disturbed Zones). In this paper, AE (acoustic emission) was chosen as a measure of stress change in the rock mass around underground caverns. By using the PFC^2D code to represent rock mineral grains by discs, we simulated the AE behavior under changing stress conditions in laboratory tests. Furthermore, relationships between in-situ AE behavior and stress paths during a cavern excavation were established and a fundamental study on the estimation of rock mass behavior based on field AE monitoring was carried out.

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Time dependent behavior of rock mass should be considered for the evaluations of long-term stability of tunnel.
In this paper, the FEM analysis based on incremental method was carried out to evaluate the effect of tunnel support, assuming various stiffnesses and setting timings, for long-term stability of a deep underground tunnel in soft rock. Time dependent behavior of rock mass was numerically simulated using compliance variable model proposed by Okubo et al.
The results showed validity of the methods proposed in this paper, and its applicability for design and long-term assessment of tunnel was discussed.

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In this paper, a deterioration hazard model is presented to forecast the expected life length of the facilities and equipments on the highways. The main focus of the paper is to present a methodology to conquer the estimation bias issues caused by incompleteness of the data set that a part of the information regarding the life length is missing. The incompleteness of the data structure is different in response to the difference of the monitoring schemes. It is necessary to develop the estimation methodology of the deterioration hazard models considering the incomplete availability of life length date of the observed samples. The applicability of the methodology presented in this paper is examined against the real world data concerning the facilities and equipments on the highways.

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