Quasi-3-dimensional seepage of groundwater was analyzed using the finite element method, to investigate the behavior of groundwater level in and around a tunnel during excavation utilizing the dewatering method. The simulated results agree well with the observed patterns of the groundwater distribution. In addition, effectiveness of water level control by distributed well points was analyzed using an unsteady 2-dimensional saturated-unsaturated model applied to the vertical plane across the tunnel cutting face. The results indicated that, by installing well points as excavation proceeds, the water content and, thus, the stability of the cutting surface can be effectively controlled.

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In this paper, an attempt is made to apply the Fuzzy sets theory to a quantitative estimation for the possibility of accidents in a tunnel-face under construction. The method proposed here uses the degree of belonging and the similarity of Fuzzy clusters as the membership functions for the possibility of accidents. The proposed membership functions lead to a crisp value, namely “Possibility indicator”. In addition, “Fuzzy distribution entropy” is defined so as to know the certainty of the clustering parameters and Possibility indicator which are used. In order to verify the applicability of the proposed method, a estimation sample is demonstrated.

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Most of the design methods for the geogrid reinforced-soil wall are based on the theory of rigid-plasticity which takes no account of displacement and deformation of reinforcing material in soil. However, pull-out resistance of the geogrid in soil depends on the displacement of the grid junction.
In this paper, finite element analyses of the geogrid reinforced-soil walls are performed. The method used here is capable of taking account of the mechanism of pull-out resistance of the geogrid in soil obtained from the pull-out tests on the geogrids. A practical design method for the geogrid reinforced-soil wall is proposed, which consists of a set of design charts determined from the finite element analyses.

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Among various soil improvement methods for soft soils, preloading with vertical drains is often the most effective method to increase bearing capacity and to reduce residual settlement. For such soil improvement being successfully completed, the most important technical task is the prediction of consolidation behavior and laboratory soil testings made before construction works alone are insufficient to give satisfactory results. Settlement and settlement rate should be monitored carefully during and after execution stage of in-situ loading.
In the extensive area of soil improvement project for coal yard construction on soft reclaimed clay at the Hekinan thermal power plant in Nagoya, test embankment was decided and the behavior of the improved soil foundation was monitored, the purpose of which is to provide data to assess total settlement, the rate of consolidation and the increase of undrained shear strength due to partial drainage. The overall performance of the test embankment has shown that vertical drains would be required to get sufficient drainage for both embankment stability and consolidation rate, and would enable preloading to be completed within the duration of the remaining construction program.

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The authors have developed a data-base system for the physical and mechanical properties of rock and rock mass especially for the initial design of tunnels by NATM. The features of this data-base system are described and the capabilities of the system have been demonstrated. By processing the all data of the system, it has been found out that the physical and mechanical properties of intact rock and rock mass can be predicted in terms of longitudinal elastic wave velocity (V_p). On the basis of this finding emprical relations are suggested for the estimation of the properties of rock mass by using the insitu and field wave velocities and the properties of intact rock. Finally, a new proposal is made for the evaluation of properties of rock mass grade of the rock mass classification of Japan Roadway Association (JRA) in relation to the suggested formulas and wave velocities.

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The Defense Agency has a large number of airfield which concrete pavements were deteriorated. As a result, the amount of maintenance work required to keep these pavements in service is steadily increasing and it is very important to quantify the deterioration of airfield concrete pavements. In this study, measurements of deflection and strain of concrete slab and coefficient of bearing capacity of base course are performed in the test pavement and deteriorated airfield. From the results of measurements, it is shown that the strain (or stress) is fairly well estimated from deflection measurements. The idea of effective thickness or effective thickness ratio of concrete slab is introduced to evaluate the structural deterioration of pavements. It is shown that the effective thickness or ratio is an index of structural deterioration of airfield concrete pavements and the reliability of proposed method is experimentally confirmed.

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A new lift-up method for prestressed concrete (PC) pavements has been developed as a rehabilitation method for adjusting the unevenness of pavements, when they have unacceptable settlement and differential settlement in particular. The procedure of the newly developed lift-up method is as follows. Installation fittings for jacks and reaction beds are provided only at the settled area of the pavements when lift-up work becomes necessary. Hydraulic jacks are attached to the installation fittings, the PC slabs are lifted up and finally, the gap created between the PC slabs and the base courses is grouted. The lift-up operation is conducted by automatic control of the jack stroke lengths.
It is confirmed from the results of the lift-up tests in test pavements that PC slabs can be lifted up rapidly, precisely and safely by using this newly developed lift-up method.

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The photoelastic stress freezing method has been used to determine the three dimensional distribution of stress around three types of tunnel intersection located in the elastic rock mass model and of stress in the lining around the same types of intersection located in the plastic rock mass model.
The results of the study indicate that maximum circumferential stress increase ratio in the lining at the corner of the intersection is approximately equal to that in the elastic rock mass located in same points. And the maximum stress on the wall of the tunnel opposite to the corner is not significantly influenced by the presence of the tunnel intersection.

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One of most importances to enhance durability of concrete structures is design details which strictly governs an easiness of concreting works such as pouring and compacting fresh concrete, as a result, which determines quality and performance of durability of structures. From this point of view factors on design detail have been discussed verifying by some experimental works focused on water penetration at the surface layer of members and a new format for design drawings concerned with concrete cover is proposed. Authors are certain that this paper could assist a spread of Proposed Recommendation on Durability Design for Concrete Structures published by JSCE Concrete Committee.

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Concrete for construction material, comparing with steel, has characteristics that the quality is affected very much by practical construction procedures in site. For minimizing defects of concrete structures it is important to pay our attention not only to the methodology of construction itself but also to the management system such as a format of specifications. Recently highlighted problems have been discussed that cover a relationship between slump value and workability of fresh concrete, and between curing period and methods. A new format for special specification of the articles on concreting is proposed for practical use of Proposed Recommendation on Durability Design for Concrete Structures published by JSCE.

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In reinforced concrete structures the surface layer has an important role to prevent external attacks which can make causes for corrosion of reinforcing bars. For realizing dense and non-porous concrete on unformed surfaces a surface tamping vibrator has been developed and applied in practical construction procedures. Effects of the equipment has also been verified by some experimental works with checking a ratio of flexunal strength of specimen between with and without tamping procedures. According to the practical and experimental results standard usages of the surface tamping vibrator is proposed for surface finishing to enhance durability of concrete structures.

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Although foundation grouting for dams is always performed as one of the most important foundation treatment works, the prediction of necessary cement takes is considered to be difficult. In this paper, several dam grouting projects of granitic rock foundations which have similar specifications have been reviewed, and the results indicate that there exists good correlations between Lugeon value and unit cement takes in grouting procedure.
In field practice, Lugeon value is obtained by using the water pressure tests prior to the grout injection, and the value is used for determining the details of further grouting works. The value suggests the properties of rock foundations, but it has been considered to be irrespective of cement grout takes. The study of this paper concludes however, that total amount of grout takes can be predicted from the initial Lugeon value macroscopically.

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This study presents the formulation of an optimum design of smooth blasting using a manual drilling machine in hard-rock tunnelling and the cost estimation of overbreaking and underbreaking. The proposed design method aims to minimize the total expense of the extra concrete cost in the region of overbreaking and of the labour cost required to remove the unbroken rock in the region of underbreaking. The design variables is the collaring radius ΔR only. The calculated results indicate that the drilling precision of the look-out angle is the most important factor in the optimum design of smooth blasting in tunnelling, in the case of using a manual drilling machine. The results also indicate that 40% of the total expense can be saved by the improvement of drilling precision and the application of an optimum design.

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A survey of the design method of preventive structures against rock falls and an improved design procedure are presented.
At first, a current investigative procedure of slopes before the design of preventive structures is outlined and a present design method is generally remarks. Secondly, a motion of falling rocks and an estimation of falling speed and location of rocks are described.
Thirdly, many formula estimating impact design load derived from the elastic contact theory, the elastic or visco-elastic and plastic theory and experimental results are discussed.
Finally, a rational design procedure is proposed.

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With regard to the construction of the 3rd stage, No. 2 Haneda Tunnel for the Metropolitan Expressway Bay-Shore Route, the recharge well method was adopted to prevent the land subsidence caused by lowering of the ground water level due to pumping well. We could decrease the consolidation settlement of the ground within the allowable value by this method. This report deals with the plan, design, maintenance and effect of the recharge well method by monitoring ground water levels.

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To root out Minamata disease, caused by the sewage accumulated in fish and shell fish, a large-scale sediment disposal work was conducted with a special care to prevent a new pollution. The basic approach to sediment disposal was to construct a highly watertight revetment for reclaiming the inner area of the Bay and then to confine sediment, dredged from the remaining contaminated area. Before sediment disposal, boundary nets were installed to enclose the work area to prevent the mixing of contaminated and non-contaminated fish. Dredging work was successfully done by using four cutterless suction dredgers, newly developed in advance for minimizing muddiness due to dredging work. Sediment, discharged into the reclamation area, keeping it under water, was covered with a sandproof membrane, particular volcanic ash earth with light weight, and mountain soil, successively.

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In recent years, some of mini-hydroelectric power stations came into use FRP pipes in place of steel pipes for their penstocks. This report explains some data for designing FRP pipes -allowable stress of their components-, and how to determine pipes' thickness, -trial and error calculation should be done on the severest condition-. And the report also refers to the observation results at a power station in Kanazawa city. They showed that the actual measured value corresponded well to the calculated one on static condition. On dynamic condition, at Cut-off test, pipe's wall vibrated very little risen from water hammer. And the safety of FRP-penstock was warranted

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One of the most important problems in tunnel construction is the stability of the tunnel face. This is controlled by a variety of factors such as the soil, the overburden, the ground water, the springing water and the tunnel construction method.
Therefore, by analyzing these problems on the basis of a survey of the reports, the relation between the stability range of the tunnel face and the values of the soil were studied. Further, when collapse of tunnel face in sandy ground were studied from the standpoints of soil and construction method, it was proved that about 70% of these collapse of tunnel face were attribute to the construction method.

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