Engineers are often faced with complaints of noise and vibration caused by rock blasting. In these cases some criterions of blast vibration and noise in order to satisfy complaints are considered on site, and a control system for blasting work by measurements of blast vibration or noise is often used. In this study for the establishment of a reasonable control system, firstly true effects on people caused by blast are reported depending on the results of monitoring on residents in the actual site. And then the comparisons with the results of monitoring blast vibration on residents and the results of measurements of vibration level are described. For the conclusion in this paper it is evaluated the results of monitoring for optimization of blasting work.

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Pre-lining methods are recently taken notice of as new type of tunnel construction methods. The New PLS (New Pre-lining Support) Method is one of pre-lining methods, in which the perimeter of the tunnel face is excavated with a chain cutter, and immediately reinforced with a concrete shell. The method was applied to a three-lane tunnel construction after some tests and trial works.
This paper outlines the New Pre-lining Support Method and describes the effectiveness and workability of the method through the tunnelling work.

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Recently, it has been difficult to secure a large disposal area to store removed soft clay. The recycle of dredged soil including soft clay is coming a social concern. The quays of caisson type in Kobe Sea Portwere destroyed by Hanshin-Awaji great earthquake. In the reconstruction, it was important consideration to reduce the earth pressure at the earthquake time, artificial light weight material (treated soil with air form) should be applied to back fill in the sea water. The authors carried out laboratory and field tests, and developed a new construction system. The new material was clarified to satisfy the design condition by the tracking tests.

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This report concerns on the various criticisms on the auxiliary methods which applied in an actual weak rock tunnel construction. A series of questionnaire was given on a series of the selection and application of auxiliary methods in a tunnel construction. It asked answers on each selection or application from the safety, economical, easiness, reliability, and overall point of views. 101 people from clients, site and design engineers filled out the questionnaire. The statistically analyzed results showed a tendency of the criticisms which slightly depends on the occupation of an individual.

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At Shirashima Oil Stockpiling Base, we put back-filling rubble behind a breakwater as an reinforcement against to the waves. We practiced an indoor experiment on resistance force from rubble to the breakwater. This paper describes the breakwater's anti-slide stability with consideration of increasing resistance force with rubble's displacement. About anti-slide stability, we ascertained that back-filling rubble have an enough effect on restraint of the breakwater's sliding displacement.

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The electrical prospection methods like the charged potential method have been applied for leak detection of landfill geomembrane liner. In these methods, leakpoints of liner are detected and located by the distortion of electric potential or resistivity contour lines. But, it is very difficult to detect the leakpoints, because the contour lines are distorted by the shape of the landfil sites and the quality of waste. Authors developed a new method to search the leakpoints without affection of the shape of landfill sites, on measured the difference of electric potential of 2 electrodes at same distance from the current electrode by the differential amplifier. This paper presents the principle of the method and effectiveness of the measuring system.

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Frost damage of concrete structures can be classified into initial frost damage that occurs in the early stages of the concrete hardening process, and frost damage that occurs in hardened concretes. The former can be prevented by the improvement of curing methods. In the latter case, the frost damage has been greatly improved by the employment of AE agents and the proper mix proportion. However, many structures are still being subjectedto deterioration due to frost damage. In this study, factors of occurrence of frost damage were systematically investigated and the possible causes of resultant frost damage were analyzed. Paying attention to the fact that frost damage occurs even in AE concrete, the causes weres investigated by laboratory tests. In addtion, a method was proposed to predict frost damage.

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Low level radioactive concrete waste will be produced in future by breaking up the nuclear facilities, and the waste will be disposed in shallow depth of ground. In order to prepare for those situation, it is needed to clarify the compaction properties of concrete waste.
In this study, full-scale concrete structure specimens were broken up, and compaction tests on concrete waste were performed. From the test results, the porosity distribution of the compacted concrete waste were clarified, and close correlations between the density distribution along the depthand the number of compaction with roller were found.

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In this study, high-strength shotcrete were patially applied for the large scale tunnel in order to certificate the effect of high-strength shotcrete for down of construction cost of large scale tunnel.
Prior to the application of high-strength shotsrete, field tests were carried out to chose the materials and mixture proportion of high-strength shotcrete and FEM analysis were done to certifcate the properity of the reduction in thickness of shotcrete, length of rock bolts and size of steel supports by using high-strength shotcrete.
From the field tests, it is clear that the strength of 30-60N/mm² can be obtained economically chosing materials and mixture poroportions properly. And from the results of FEM analysis and the mesurement data during tunnel excavation, it is possible to down the construction cost and term of large scale tunnel by using high-strength shotcrete.

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Experiments were designed to investigate near field damages caused by blasting in a rock cavern. Six blast holes were detonated with well-designed blast parameters and drilled cores, oriented normal to the blast surface, were obtained sequentially from a retained wall. Covered rocks were removed so as to enable observation of the damage zone. Both the pre-existing cracks and the blast-induced cracks on the wall were observed visually.
Primary waves propagated normal to drilled core axes were measured in order to evaluate blast-induced cracks. It has been found that surrounding region within 30cm from the blast hole was seriously fractured into small pieces and the region within 50cm was damaged and resulted in numerous small cracks. Primary wave recovery was found beyond these regions although a few radial cracks were detected up to 1m from the blast holes. No blast-induced damage was found beyond this region.

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Concerning a new jet grout forepiling, the authors describe that the dimension of it can be obtainted while driving, and assume that the replacing rate of soil particles with hardener obtained by measuring the specific gravity of the discharge slime influence on the strength of the forepile.

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We are proposing use of Improved Trial Wedge Method (ITWM) as a rational evaluation method of earth pressure on the cantilever retaining wall. However, this method is limited to linear failure surface. When backfill slope is not uniform, failure surface become nonlinear making ITWM inapplicable. In order to solve this problem, we enhanced ITWM to apply to the nonlinear slide problems.
In order to prove applicability of this method, we compared analytical results of enhanced ITWM and conventional ITWM. We also performed model test under centrifugal force to compare experimental and theoretical results.
As the results, we discovered that the shape of failure surface had little effects to analytical result, and there were close results between experimental model and theoretical results of ITWM.

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The Minamata Bay Environmental Restoration Project was carried out in order to rehabilitate the Minamata Bay environment.
This study presents the process of planning and implementation of the project. We also evaluate the degree to which the environment was improved by the Minamata Project and the economic and societal effects of the project, and analyze the actual conditions of the environmental restoration like changes of mercury concentration in fish.

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