In recent years, the shotcrete has been increasingly applied to a permanent concrete lining of a tunnel. However, the durability of shotcrete is not yet established because of temporary structure. This paper investigates the influences of the factors involved in shotcrete such as the execution intervals between the shot layers, the kind of accelerators and addition of dust-reduer, upon its strength and durability characteristics particularly upon the resistance to freezing and thawing, by doing experiments and a statistical analysis. From the results of these investi gations, the following conclusions have been drawn: (1) The kind of accelerators have large influence on the quality of shotcrete. (2) Addition of dust-reducer increases resistance to freezing and thawing on account of tiny air bubbles produced in concrete, though with unfavorable effects on its strength and carbonation. (3) Execution intervals do not contribute much, except to improvement of tensile strength.

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Three-dimensional seismic analysis of a gravity-type steel platform, which is proposed for oil production and storage at marginal offshore fields, is carried out. The present structure is characterized by a massive top deck, a six-leg flexible tubular framed jacket, and a wide spread out base tank. The interest for investigation is, therefore, placed on the dynamic interaction of the structure with soils at site. Different modleings are taken for structural parts in view of the accuracy for response analysis. The dynamic substructure method is applied to advantage for evaluating the soil-structure Interaction effectively. Through the numerical computation, some useful informations are derived for the seismic design of the concerned offshore structure.

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This method is a new counter measure system for sand liquefaction. The principal purpose of this method is based on promoting drainage. The slender polyethylene pipes used in this type of drainage are 5 to 10 centimeters in diameters with many small holes, in the body of the pipe. These pipes burned into the ground at intervals of 60 to 150 centimeters, surrounding the foundation of structures.
When the excess pore water pressure builds up during earthquakes, pore water flows into the pipes. As a result, build-up of excess pore water pressure can be reduced. In order to investigate the effectiveness of this method, two laboratory tests and three field tests were performed. The result shows that this method is applicable for preventing sand liquefaction in practice.

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This paper aims to develop the methodology to calculate the expected construction duration. In case of a construction works in a remote area where the supply of parts are difficult, the number of equipments is decided considering the possibility of time over-run due to equipment failure. That is, the number of equipments is increased from the most efficient capacity and number. Because, several, equipments make it possible to continue construction even if one equipment is failed, and the parts of that can be used as the source of parts when the second equipment is failed. This paper analyses these situation and shows following conclusions: (1) Serial parallel system represents this situation, (2) An equation is shown to calculate the probability of some number of equipments are failed at time t, (3) An equation is shown to calculate the expected capacity and the expected duration.

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The reserch work of Proctor gave us the useful theoritical idea for compacting soil. Since then, Proctor type criterions have been popularized in all the world. But it has been known that there are some troubles in the embankment constructed with some special soils.
In this paper, the deformation mechanism that the embankment built with softrock which is one of special soils is suffered, especially when it is submerged with water, is studied and the estimation method of embankment deformation due to water increase is proposed. In addition, it is reported that the deformation is one of the most important factors for designing embankment.

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This paper studies behavior of a reinforced concrete ring subjected to static load. The study was conducted on two tanks at Mutsu-Ogawara Oil Storage Base, that is the first national project for oil storing purpose. Lateral unit pressure and lateral force were measured by earth pressure gages and load cells, respectively. In order to investigate the influence of the lateral force, stresses in the reinforcing bars and concrete were measured.
The main conclusion are as follows.
(1) Temperature stress in the ring caused by seasonal temperature change is relatively large and can not be neglected.
(2) Stresses in the ring measured during the water test by the lateral force are smaller than those estimated on paper.

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Field experiments on the compaction for Roller Compacted Dam (RCD) concrete have been conducted to investigate its compaction mechanism. In these tests, no slump concrete with poor cement content was spread in 18 to 25cm layers by bulldozers, and three layers were compacted in 54 to 75cm lifts by vibratory rollers. Non-contact type displacement devices were embedded at the top of each bulldozer spread layer to measure the internal displacement during bulldozer spreading and vibratory roller compacting. Density and unconfined compressive strength were tested for the drilled core specimen obtained from hardened concrete. From these test results, several conclusions were drawn on the (1) effects of bulldozer and vibratory roller on the compaction of RCD concrete, (2) the procedure to determine the most suitable quantity of cement paste content in the design of mix proportion and, (3) field quality control method for compaction.

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The traffic data available which to evaluate the fatigue safety of concrete slabs and girders of bridges and pavement of roadways is limited. The reason is that the acquisition of the traffic data requires a lot of time and manpower, and therefore involves a large cost. Over the past few years, the authors have been trying to develop a portable system which monitors the traffic flow and records wheel position and passing times of vehicles at any point on a roadway. This compact system composed of a switch mat, data-logging box and personal computer, also has the ability to process the data and provide histograms of speed and type of vehicles and lateral distribution of wheels, and allows the collecting of a large amount traffic data in various times with minimum cost.

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The purpose of this study was to develop an observational control system for excecuting excavation works using data based on minimum measurements. Here, method of analysis and results of verification based on measurement are shown. The analytical procedure consists of 3 stages; analysis under present condition for estimating wall displacement and bending moment, back analysis for estimating lateral pressure and coefficient of horizontal subgrade reaction and prediction analysis based on these assumed parameters. The use of the extended Kalman filter of control theory is a spetial feature of the back analysis which has a greatest importance relative to the purpose of this study.

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Low-cost earth pressure and pore pressure gauges using pressure responsible conductive rubber were newly developed to promote the observational procedure during construction. Their performances were tested by indoor and outdoor investigations. The features of the pressure gauge are as follows: (1) Low-cost. The cost of the new pressure gauge is about 160yen. (2) The pressure-response curve of the pressure responsible conductive rubber tends to migrate with the increase in number of repeated pressure application. Since this migration of the pressure-response curve settles gradually when applied a great number of repeated pressure application, the preliminary application of cyclic repeated loading is needed. (3) Durability and water proofness are proved. (4) The pressure responsible conductive rubber has a property of viscosity (creep) and a relationship between pressure and electric resistance of the rubber shows a hysteresis loop, therefore, it is not appropriate to use for the measurement of dynamic behaviour. (5) Rubber size has an effect on a pressure range at which the rubber is able to respond properly.

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There are two approaches for the estimation of the blasting vibration, which are based on the peak particle velocity (PPV) and vibration level (VL). The relationships between the PPV and the VL have been investigated but there are still area to be investigated. This study aims to establish the relationship between the two, and to propose a predictor for the VL from the PPV of impulsive waves. Although the VL is defined by using the root-mean-square of the accelerogram which is filtered through the response characteristics of human body, the VL was obtained from velocity wave instead of from the filtered accelerogram in this study. The proposed predictor is a function of two variables, which are the PPV and the duration time of the velocity wave. It was found that the predictor is useful for practical purposes.

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This paper describes the low vibration blasting methods with continuous slots based on the field tunnelling tests. There are two methods, which are blasting with a peripheral slot and blasting with a center slot. In the former blasting method, a continuous slot around the tunnel periphery is drilled with the slot drill machine and then rock surrounded by the slot is excavated by blasting. According to field tunnelling, the vibration velocity was reduced to one fifth of that in the conventional blasting method and the total charge was reduced to two fifth. In the latter method, the center slot is used as the center cut holes. The vibration velocity was reduced to one third and total charge was reduced to four fifth.

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The design for reinforced cut slope with bars is not always reliable due to the many unknown soil properties of natural ground. It is considered that observational procedure is one of the methods to solve this problem.
The present paper is concerned with analysis method for observational procedure on reinforced cut slope. The authors try to explain the results of field loading tests on actual-scale specimens and the behaviors of the actual, reinforced cut slope by two analysis; FEM considering slip joints and slope stability analysis method considering extention of bars.
As a result, it was proved that both analysis methods are applicable to observational procedure of soil-reinforced earth method.

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This paper studies on the factors which affect stresses in a RC ring of a tank foundation constructed at Mutsu-Ogawara Oil Storage Base. Regression analysis are conducted on measured data and it is confirmed that changes in the stresses and earth pressure intensity depend on a seasonal temperature change at the site. Then, study is made on factors that restrict free movement of the ring. A degree of the restriction is also investigated.
The main conclusions are as follows.
(1) The restriction was caused by the lateral resistance of soil.
(2) The stresses in the ring decreases as rigidity of the ring increases.

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This paper deals with the construction of the fuzzy controller for shield tunnelling and the result of the field test. The fuzzy controller has two functions. One is controlling shield jack speed and rotation speed of screw conveyer for pressure regulation at a muck chamber, the other is making choice of shield jack patterns for direction control of a shield machine. This fuzzy controller has a parallel circuit structure. By this way it can control complex systems by a few control rules founded on the know-how which skilled operators have obtained through their experiences. The fuzzy controller aims at shield machine control by skilled operators. So the root mean square of the diviation in operation between skilled operators and the fuzzy controler is defined as the performance index. The optimum controller can be obtained when the performance index is minimized.
The field test shows that the fuzzy controler can control shield machine as well as skilled operators.

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It is well known that network technique e. g. PERT/CPM has not been diffused in construction site-offices for planning and scheduling. We thought there were two main reasons which were a insufficiency of network method and some difficulty to use computer in site-office. Then in order to improve such drawbacks, we have been tried to renew PERT/CPM, and we have developed a personal computer-based management system called PF-NETS, Planning Forecasting—NET work System. In this paper, we epitomize our recent results of study. And the purposes of this research project are: (a) to demonstrate the viability of applying this system, (b) to find out some problems, and (c) to show the way to explore them by A. I. techniques. In this process we discovered the new concept which indicate a discrepancy between hierarchical networks. And we named the higher level network “Conceptional Network”.

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In order to study the effect of the steel bar reinforcement in a sandy slope, triaxial compression tests and vertical loading tests for the reinforcement slope model were carried out. In the triaxial compression test, the setting numbers and the friction condition of steel bars were varied. In the vertical loading test, the setting direction of reinforcement bars was only varied, and the surface deformation of the model slope and the stresses of the reinforcement bars were measured. Through the test, it is shown that the reinforcement becomes more effective when the reinforcement bars can confine the soil extrusion between the reinforcement bars.

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Sand drain works which accelerate the consolidation of the clayey stratum have been successfully adopted to improve the soft seabed in many harbour construction projects for some decades. The works especially in the short-time construction, however, require elaborate observations and construction processes all through the term due to some uncertain phenomena of its consolidation.
This paper tries to show that pilot observations of the actual consolidation based on the site experimental construction can be instructive to a safe and swift construction of a large-scale reclamation island with following reasons.
(1) The pilot observation and analysis concerning the settlement and strength of a clayey stratum contribute to forecasting consolidation trends with sufficient accuracy.
(2) The original construction processes can be reasonably adjusted with this forecast.

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The drilling rate of rotary percussion drill bit depends on the revolving energy and the impact energy of drifter as well as the characteristics of rock mass. The rotary percussion drill tests were executed in-situ for 13 kinds of rock mass using 12 actual drill machines to clarify the interrelations between them. As the results, the drilling rate has been expressed as the function of the revolving energy, the impact energy, the bit diameter, the coefficient of crack of rock mass and the Shore hardness or the amount of Los Angeles abrasion or the radial compressive strength of rock specimen. On the other hand, the rock mass properties could be determined by measuring the drilling rate of a standard rotary percussion drill machine.

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Pipes are often adopted as the structural members of off-shore structures because of their isotropic properties. The details of connection joints of pipe structures are inevitably too complicated to measure their sizes precisely. Difficulties arise from trying to measure these joints, called ‘nodes’, with steel tapes.
This paper introduces a new measuring method, which was developed for measuring steel bridge members using CCD cameras. This method has already been proved to be an excellent method in measuring bodies with the sizes of decameters. One of the advantages of this method lies in the fact that processes can be performed without touching bodies to be measured. By virtue of this characteristic, one can obtain numerical results as far as the targets exist in the scope of the cameras despite the shape of the object. The results obtained, are exhibited in this paper.

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In this study, the applicability of smooth blasting for tunnelling in jointed hard rock was discussed with reference to the field measurements. In the field test, spacing, burden and specific charge were varied into three levels individually and 27 cases of smooth blasting tests were carried out. The test results were evaluated according to the over-break and under-break and the drill hole contour ratio.
The field test results showed that the variations of spacing and burden give little effect on the smooth blasting results, but a smaller specific charge gives a little better result than a larger one. The tests also showed that the joint structure has a great influence on the blasting results.

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