The washout resistance of foamed treated soil which is made of dredged slurry and is cast underwater is studied. The washout resistance test is newly developed and the following conclusions are obtained by a series of the test.
1) In a washout resistance test of the casting velocity control type, the density of suspended solid (SS) of water, pH value of water and the strength of soil after curing can be indexes of the washout resistance.
2) The results of the washout resistance test shows that, as for the foam treated soil used in this study, the mixing proportion of 180-290mm flow value and the casting velocity less than 80cm/sec are recommended to prevent the washout.
2) Foam treated soil of 15, 000m³ were cast underwater for backfilling of quaywall in Kobe Port. By using the result of washout resistance test, the observed values of SS and pH were small and the properties of the ground was uniform.

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This report is a case history of the construction work in which the artificial light-weight soils were used for the back-filling of the revetment in Tokyo International Airport. The light-weight soils were made by mixing the waste clay slurry, which was caused by the construction of shield tunnel in the airport, with cement, air foam and EPS beads. According to the data taken in the construction, the properties of the soils satisfied the range for the quality control in spite of the change of the properties of waste soil. To investigate the ground properties of the light-weight soils, the core sampling and the laboratory tests, in-situ plate loading test, CBR test, and Falling Weight Deflectmeter Test were carried out after 2-6 months after the constriction, and the comparison and discutions are made.

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Many houses and agricultural land on the low ground by the name of Annaka Triangle zone of Shimabara City were destroyed by repeated debris flows in the Mizunashi River during volcanic disaster of Mt. Fugen in Unzen. A noteworthy ground surface augmentation project is adopted to reconstruct the livelihood of the disaster victims. The process and problems of this project are studied and discussed in detail.

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An Oval Section TBM (tunnel boring machine) enables excavation of tunnel with elliptical cross section by inclining the cutterhead. It is developed to utilize the proven conventional TBM technology with minimum modifications.
An inclined cutterhead may create a number of new problems, such as inexcavation efficiency and steering, that are unknown in excavation works using a circular TBM. This paper reports on verification tests carried out to examine the extent of such problems using experimental models of the machine in an attempt to confirm the feasibility of the Oval Section TBM.

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We presented the system that can forecast the collapse of cut-off slope using standard data based on neural network in the preceding paper. Data must be carefully selected for precision forecasting using neural network. In this system, the difference between the non-collapsed data and the collapsed data causes the uncertainty in results. Especially, the rainfall data is very important factors for this system. In this research, we present new rainfall factors called n-hours rainfall and attempt to provide more information for the system to obtain more assured results. We confirm that these factors is applicable to the system.

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The present study is an attempt to develop the concrete bridge rating expert system with machine learning employing the hierarchical neural network to implement an inference mechanism. This network enables the system to facilitate the refinement of knowledge base by using the back propagation method. In this study, the training set (teaching data) for machine learning is obtained by the inspection for actual in-serve bridges and questionnaire surveys on bridge experts. Furthermore, comparisons between the diagnostic results of bridge experts and the ones of this proposed system are presents so as to demonstrate the validity of the learning capability of this system.

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Rock type slurry shield method is used for pipe jacking in various rocks. In excavating soft rock, faceplates of this type are often blocked by sticky rock chips leading to the difficulties in excavation. The purpose of this study is to research the cause of the blockage phenomenon and the method for preventing the blockage phenomenon. The artificial soft rock was used for the specimen in order to standardize the experimental condition. Flow to the cutting face and reducing of the length of disk cutter were effective for the defensive measure of the blockage phenomenon from the investigation of the mechanism which discharge sticky rock chips. Flow of slurry in chamber and the cutting face were investigated in order to apply these results to the real machine, and the situation was grasped.

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A new estimating method of concrete strength from pin penetration test using air pressure is proposed as a simple in-situ test of shotcrete strength. In procedure of this method, pins are driven on the surface of shotcrete by a conventional air pressure nailer. The compressive strength of shotcrete is estimated from the pin penetration depth. In the paper, the applicability of this method is verified through laboratory and field tests. There are intimate relationships between the pin penetration depth and the compressive strength in range of 1 to 30N/mm². Therefore, it is found that the proposed new testing method is effective for estimating the shotcrete strength. Add to this, the merits of in-situ testing method serve the purpose of proposing a new control method on shotcrete strength.

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Deformation of excavated slope stabilized by soil nailing is unclear concerning its amount and mode. A series of full-scale model tests was conducted and a number of measuring data of soil nailing cases were studied to investigate these problems.
The following results are obtained. When the slope is stable, mode of deformation is a toppling. At failure a shape of sliding is approximately a circular. In cases of soil ground, allowable displacements indicated by normalized horizontal top-of-slope displacement (δ_h/H) is about 0.4%. Stability management method using δ_h/H is proposed.

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In this paper, a calculation method of the road traffic noise along elevated tracks for L_A50 and L_Aeq using boundary element method (BEM) is presented. We have already proposed other numerical calculation method using Monte Carlo simulation (MCS). The MCS is very suitable to calculate the values of L_A50 and L_Aeq, because it can be easily simulate the direct transmission of the multi-reflection waves. However, the MCS is based on geometrical acoustics, and is difficult to compute the diffracted transmission of multi-reflection waves. Therefore, when the space between bottom of the girder under elevated road and top of the noise barrier on plane road is small. the numerical enors of L_A50 and L_Aeq computed using the MCS increase. Overcoming this difficulty, the BEM based on wave equations is applied to the calculation method of the road traffic noise.

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The new damage-inspection method for concrete pile using AE technique proposed by Mori and Shiotani (1998) was applied to several pile foundations damaged during the 1995 Hyogo-ken Nanbu earthquake. In this paper, the development of portable suspended wave-guides and their application results are discussed compared with the result of conventional inspection methods. The comparison verifies the effectiveness of the proposed method. Furthermore, the comparison between direct AE measurement on pile and indirect measurement with wave-guide suggests the characteristics of AE wave transformation through ground.

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It has been needed that establishment of rational and economical grouting method which is one of the water tight construction method in rock mass. Authors study for soil cement grouting in order to cut down the grouting cost and improve the quality of grouting materials.
In this paper, Authors carried out the in-situ experiment using soil cement grout and verify the availability of soil cement grouting.

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Embankment slope surfaces are frequently covered with protection works to prevent collapse by rainfall. In this paper, in the first we confirm effects of slope protection works on railway embankments through analyzing some past collapse cases in which the embankments were covered with protection works. Furthermore, we compare estimating critical rainfall of non-covering protection embankments with the actual rainfall after covering protection works, and shall try to quantitative evaluation for the protection works.

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This paper presents the techniques applied to stabilize a progressively toppling steep rock slope (waterfall) situated about 20m downstream from an intake dam. First, using a distinct element analytical model of the slope a suitable rock reinforcement system is designed and analyzed so as to prevent the instabilities of the slope. In addition, a rigorous process of construction works is followed while installing the rock reinforcement elements in order to protect and enhance the geoenvironment of the site. Completion of the construction works has convincingly resulted the original aesthetic of the waterfall assuring its stability during flooding, the commonest natural event of the area, with reasonable cost.

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