[in Japanese]

View full abstract

The aim of this paper is to evaluate the effect of planeload of a heavy off-the-road dump truck on the compaction of a thick finishing decomposed granite soil. The compaction test using off-the-road tire was executed in a large soil bin. A proposed soil compaction model was used to predict dry density of sandy soil. It was estimated that the pressure bulb reached the depth of a thick layer under tandem wheels. Furthermore, it also shows that the dry density achieved a comparatively high value due to the dilatancy effect accompanying with an occurrence of alternative shear stress during the running of dump truck, and the dry density decreased rapidly to the low constant value at the deep stratum.

View full abstract

In order to develop a better procedure for reducing the cost of construction of underground openings, the authors focus on the cablebolting. A field experiment was conducted during constructing an underground powerhouse to investigate how cablebolts work for pre-reinforcement of rock mass. It is found that cablebolting has a potential to control the rock displacement in the vicinity of the cavern wall due to excavations. The mechanism of the effect of cablebolts is also discussed by numerical simulations on the basis of filed measurement results.

View full abstract

Tokyo Metropolitan Government, The Bureau of Water works has been conducting a seismic reinforcement work onto the existing earth dam, “Yamaguchi Reservoir” completed in 1934. During the renewal works, the most difficult construction issue was to secure the stability of the existing dam and the new counterweight fill.
This paper describes the auther's engineering aproaches using observational procedure and analytical prediction to control the stabilitiy of the dam.

View full abstract

In order to establish the rational design for civil infrastructure, the life cycle cost of structures is the most important. Various factors are needed to evaluate appropriately for the life cycle cost. This study focused on concrete slab, including concrete pavement, subjected to anti-freezing agent. This paper presents the evaluation of life cycle cost of concrete slab in the circumstance of deterioration due to the anti-freezing agent. As the evaluated results, cover thickness of reinforcement especially influences the life cycle cost.

View full abstract

The purpose of this paper is to innovate an optimum trench excavator crushing a hard rock mass by means of a decrement of thrust, a prevention of wear of cutting blade, a decrement of specific cutting energy, and an increment of product of excavation due to an application of mechanism of edge excavation. Here, a test machine of hard rock trench excavator having 490 kN vehicle weight, 140 cm diameter of cutting drum mounting six double crush type disc cutters and six ripper type disc cutters, was designed in the stand points of an excavation force, an excavation speed and a product of excavation. As a result, it was estimated that the average product of excavation could reach up to 0.113 m³/min (6.78 m³/h) which was 2.51 times that of conventional excavator.

View full abstract

We are developing a new inspection technique for tunnel concrete lining using shock acoustics, which mechanizes and automates a work from shock to the health judgment.
Furthermore we have researched the method of making the shock energy constant and recording shock acoustics without changing the frequency characteristic. As the result, we were able to decide the better specification of the inspection device.

View full abstract

Recently collapse due to fatigue of steel sign poles on the highway bridges with rubber bearings becomes social issues. So we had a discussion meeting with different field's engineers, where reinforcing steel pipes with ultra-violet-curable FRP resin sheet was proposed. In order to confirm the effectiveness of this material on the fatigues life, full-size model tests with and without the sheets were conducted. As results, a usefulness is recognized from the fatigue tests.

View full abstract

This paper describes a maintenance management system for hydropower civil engineering structures represented by spillway radial gates based on Reliability Centered Maintenance (RCM). RCM provides a framework of the practical maintenance rationalization strategy. The proposed system consists of qualitative and quantititative analysis parts and it enables us to determine appropriate maintenance altenatives including inspection interval using the past records of repair, renewal and repainting rates instead of the failure rates. The proposed system is applied to an existing spillway radial gate and, its applicability and future subjects are discussed.

View full abstract

In this paper, we proposed a methodology to support decision making for prioritization of seismic retrofit for existing structures based on the concept of Life Cycle Cost taking into account seismic risk. We explained how to make prioritization of seismic reinforcement for existing structures and how to treat structures which have different service periods because the deterioration with age should be taken into account. As an example, the methodology was applied to actual road bridges in Osaka Wangan Route and the applicability of this methodology was examined.

View full abstract

Evaluation of the life cycle cost for the infrastructure is required for decrease of the construction cost. The risk cost is the most laborious work in the determination of the life cycle cost for bridge structures. The risk cost has not been evaluated even for the members of the structure. The present study aims to predict deterioration process and to propose an evaluation procedure for the risk cost of RC slabs under repeated fatigue loading. The present paper indicates the results of the calculation of the failure probability of slabs with different thickness and replacing cost including profit-and-loss costs. These provides the risk cost for RC slabs under fatigue loading.

View full abstract

This paper presents methodology associated with asset management of road slopes considering performance deterioration of groundwater counter measurement system. In detail, the methodology to evaluate life cycle cost, LCC, of road slopes, which is essentially equivalent to sum of maintenance fee and expected loss under specific condition, is presented. And, groundwater behavior considering performance deterioration of groundwater counter measurement system is predicted by adopting multi-tank model. Finally, results make it clear that LCC evaluation method developed in this study is applicable to strategically plan budget allocated for maintenance of road slopes with deteriorating groundwater counter measurement system.

View full abstract

A three dimensional product model for prestressed concrete bridges was developed in this research to enable the interoperability among various heterogeneous application systems, based on the Industry Foundation Classes (IFC) with the aim of developing an international standard. To validate the developed product model, we integrated four systems, i.e., a 3D CAD system, a design checking system, a system for checking cover of reinforcing bars, and a system for checking interference among elements by using the product model. The integrated system was applied to several real prestressed concrete bridge design cases and demonstrated the effectiveness and practicality of the product model.

View full abstract

This paper proposes a priority ordering system by using a combination of neural network system and genetic algorithm. The proposed system is applied to the real priority ordering problem of countermeasure planning to the slope failure which includes the subjective sense of value of planner. Applying the system to the real engineers interactively, the robustness of the proposed system is confirmed. And the time variations of sense of value in an engineer or the differences of sense of value among the engineers are pointed out. Finally, the capability of the system to consensus making for multi engineers is suggested.

View full abstract

It is considered that cement treated soil improved by deep mixing method has high durability for long time. However the property change of cement treated soil after several years were still not clear. The purpose of this study is to propose a numerical prediction method for Ca leaching from treated soil. This numerical prediction method consists of 4 models named as (1) ion migration model considering with the effect of other ions, (2) Ca adsorption model in surrounding soil, (3) dissolution model from hydrates and (4) carbonation model in treated soil. As a result of this paper, a numerical method for Ca leaching from soil improved by deep mixing method could be proposed and the validity of the method was confirmed by conpairing with the available field data.

View full abstract