Journal of Disaster Research
Online ISSN : 1883-8030
Print ISSN : 1881-2473
ISSN-L : 1881-2473
12 巻 , 3 号
選択された号の論文の25件中1~25を表示しています
Special Issue on Infrastructure Maintenance, Renovation and Management
  • Kazuo Kyuma, Yozo Fujino, Kohei Nagai
    原稿種別: Editorial
    2017 年 12 巻 3 号 p. 394-395
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Building a sustainable economy is one of Japan’s most pressing issues today, and the only path forward is through innovations in science and technology. Under the leadership of the Prime Minister and the Minister of State for Science and Technology Policy, the Council for Science, Technology and Innovation (CSTI) has taken a high-altitude look across Japan’s ministries, proposing a comprehensive policy for science, technology, and innovation. As part of this policy, the SIP program has been designed as a fast-track research and development project, encompassing basic research, practical adoption, and commercialization. This nationally-sponsored program for science and technology innovation crosses the traditional framework of Japan’s ministries and agencies, as well as the traditional boundaries of scientific disciplines. The SIP has identified 11 issues from the field of energy, next-generation infrastructure and regional resources in order to address social issues, revitalize the Japanese economy, and bolstering Japan’s industrial posture in the world.

    As one of eleven themes, a new R&D program named “Infrastructure maintenance, renovation and management” was launched in 2014. The new R&D program is a 5-years program covering various subjects with key technologies such as non-destructive testing, monitoring, robotics, long-term performance prediction, development of high-quality durable material for repair and replacement, and infrastructure management using advanced information and communication technologies (ICT). The program consists of 60 research projects involving universities, research institutes and industries. This initiative is expected to prevent further accidents and setting an example for efficient infrastructure maintenance by reducing the burden of maintenance works and costs.

    This special issue aims at introducing some of the activities of the ongoing SIP “Infrastructure maintenance, renovation and management.” We are delighted to see publication of twenty-one technical papers/reports on this theme. We hope that readers would find this special issue interesting and valuable; and we greatly appreciate the authors for their contributions.

  • Saiji Fukada, Minh Tuan Ha, Kazuyuki Torii, Makoto Tsuda, Shuzo Ura, T ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 396-405
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Reactive aggregates are widely distributed throughout Japan. In the Noto region, andesite is widespread, which causes alkali-silica reaction (ASR) degradation in concrete structures. For the maintenance of local bridges, it is necessary to observe the expansion trends of cracking caused by ASR in health assessments.

    In this study, remote long-term monitoring of a four-span prestressed concrete (PC) rigid-frame bridge was performed to investigate the expansion of cracks by ASR. To evaluate the health of this degraded bridge, instead of focusing only on the locations of cracks, it was also necessary to monitor simultaneously the displacement behaviors over time of the bridge and to obtain the crack expansion trends, which could not be identified by regular visual inspections alone. Therefore, long-term monitoring and loading experiments using large vehicles are utilized to reveal the correlation between cracking due to ASR and displacement of the overall structure due to variations of diurnal temperature and the live load.

    As a result of the loading tests using test trucks, by long-term monitoring of the relationship between the temperature and the crack displacement due to ASR, the expansion trend of the crack due to seasonal variations was obtained. A particularly rapid growth trend from spring to summer was recognized. In addition, the vertical displacement of the Gelber hinge, which could be obtained from the inclination angle using the correlation between the inclination angle and the vertical displacement of the static loading tests, was estimated at approximately 30–40 mm during summer. Moreover, as another conclusion of the study, it was found that changes in diurnal temperature and the displacement behavior of the entire bridge had significant consequences on the types of crack expansion in this bridge.

  • Carlos Arturo Liñan Panting, Kohei Nagai, Eiji Iwasaki, Thein Nu
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 406-414
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    This study conducted a simple monitoring for a deformed suspension bridge in Myanmar to confirm advances in deformation and verified the structural performance by FEM. The bridge is Twantay Bridge those main towers were inclined due to the movement of anchor blocks, that resulted in lowering of the road surface level. Therefore, inclinometers were set for simple monitoring to confirm advances in the deformation. The result of measurements performed for 50 days did not indicate any significant advances in inclination with respect to the main towers. The FE analysis to evaluate the structural performance estimated the current condition of the bridge by reproducing the construction process of the bridge and simulating the setting and removal of concrete blocks used as bridge railings as well as the sliding of anchor blocks. At each step of the analysis, the results were compared with the measured data to verify the appropriateness of the analysis. The findings confirmed that the current tensile force of the cable did not result in hazardous conditions that led to the rupture of the cable.

  • Tsukasa Mizutani, Nagisa Nakamura, Takahiro Yamaguchi, Minoru Tarumi, ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 415-421
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Maintenance costs for infrastructure, such as bridges, have been increasing particularly in the developed countries. Bridge slabs are important parts of bridges; however, the evaluation of their structural conditions requires significant manpower and time because dense hammering tests have to be conducted as part of the present inspection methods. To overcome this difficulty, a non-contact inspection technique using a radar is focused in this research. Radar techniques are typically utilized in the fields of mine-search, oil-source search, and geographical archeology. However, these searches are conducted by only visually checking reflected-wave images, and thus, the evaluation strongly depends on the abilities and expertise of the inspectors. To more effectively utilize these radar techniques for evaluating a bridge slab condition, analysis of the reflected wave signals should be made automatic, fast, and objective because the number of bridges to be inspected is large. In this research, to detect the damages on a slab, some signal processing techniques for measuring the reflected wave signal by a UHF-band fast scanning and non-contact radar are proposed, and their validity is shown by applying them to the signals obtained from full-scale bridge slab models in which certain ideal damages are embedded.

  • Yasushi Tanaka, Koichi Maekawa, Takuya Maeshima, Ichiro Iwaki, Takahir ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 422-431
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Remaining fatigue life of reinforced concrete (RC) slabs subjected to traveling wheel-type loads is estimated by data assimilation procedure, i.e., coupled life-span simulation with inspection data. Multi-scale analysis (MSA) with path-integral-mechanistic models is used for the platform of data assimilation on which the visual inspection of concrete cracking on the members’ surfaces and the acoustic emission tomography (AET) are numerically integrated. For investigating the applicability of the proposed data assimilation, the wheel running experiments of RC slabs was conducted. Both crack patterns (2D) and 3D-AET were measured over the fatigue life till failure. In the pseudo-cracking assimilation, observed cracks are converted to space-averaged surface strains and the internal strain fields are simply assumed by in-plane hypothesis. This pseudo-cracking assimilation brings about fair assessment of the transient maximum deflection, but the residual deformation was found to be overestimated. Another non-destructive inspection data applied in this assimilation is the 3D-AET associated with the acoustic wave velocity, which has much to do with stiffness of some control volume with and without cracking. The AET velocity is converted to the initial fracture parameter of un-cracked concrete based on the elasto-plastic and fracture model used. Although cracking is not explicitly taken into account unlike the pseudo-cracking method, the small number of load repetition automatically generates internal cracks over the volume of analysis domains, and the remaining life of the slabs inspected was successfully estimated.

  • Shin’ichi Yuta
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 432-445
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    We have been developing the crawler dump type heavy carrier robot since 2014. This robot can effectively travel a distance of a few hundred meters both on land and in shallow water. Through the use of a remote control, the robot can carry out unmanned construction in cases of flooding and waterside disasters. This paper reports part of the results obtained during development. Specifically, we report ① the consideration on a scenario for construction during an emergency by using remotely controlled heavy machinery under flooding conditions; ② the testing and findings of the first heavy carrier robot prototype with regard to water resistance and travelling performance; ③ the method of operation guidance based on the display of estimated ego-position to control the traveling of heavy machinery remotely and the results of experiments.

  • Boyu Zhao, Tomonori Nagayama, Masashi Toyoda, Noritoshi Makihata, Mune ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 446-455
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    A smartphone-based Dynamic Response Intelligent Monitoring System (iDRIMS) was developed to conduct road evaluations with high efficiency and reasonable accuracy [1]. iDRIMS estimates the International Roughness Index (IRI) based on vehicle responses measured with an iOS application, which obtains three-axis acceleration, angular velocity, and GPS with accurate sampling timing. However, the robustness and accuracy was limited. In this paper, the iDRIMS was improved mainly by employing frequency domain analysis. The algorithm consists of two steps. First, a half car (HC) model was selected as the vehicle model, and vehicle parameters were identified through driving tests over a portable hump of known size. In contrast to the previous approach of parameter identification in the time domain using Unscented Kalman Filter, the parameters were optimized to minimize the difference between the simulation and measured hump responses in the frequency domain, using a genetic algorithm. Then, IRI was estimated by measuring the vertical acceleration responses of ordinary vehicles. The measured acceleration was converted into the acceleration root mean square (RMS) of the sprung mass of a standard quarter car (QC) by multiplying a transfer function. The transfer function, estimated through the simulation of the identified HC model, as opposed to QC model in previous approaches, reflected the vehicle pitching motions and sensor installation location. The RMS was further converted to IRI based on the correlation between these values. Numerical simulation was conducted to investigate the performance in terms of various driving speeds and sensor locations. The experiment was conducted at a 13 km road by comparing three types of vehicles and a profiler. Inaccurate IRI estimation at the speed change section was experimentally investigated and compensated. Furthermore, the improved method was applied to 72 vehicles that were driven more than 180,000 km per year. A data collection and analysis platform was built, which successfully collected and analyzed large-scale data with high efficiency. The results from both numerical simulation and real case application show that the improved method accurately estimates IRI with high robustness and efficiency.

  • Toshiki Ayano, Takashi Fujii, Kyoji Niitani, Katsunori Takahashi, Kazu ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 456-469
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Concrete deck slabs of bridges are often deteriorated by heavy traffic and freezing and thawing actions. Spraying salt during the winter further promotes the deterioration of concrete. Some reports estimate that the length of highway roads requiring the renewal of deteriorated concrete slabs exceeds 230 km. In order to extend the lifespan of damaged bridge girders, the load for these girders must not be increased. This means that prestressed concrete (hereafter, PC) members are desirable to sustain bridge life, because they can be thinner than reinforced concrete (hereafter, RC) members. In addition, to shorten the period of traffic regulation during renewal construction, precast members should be applied. One problem in manufacturing durable precast concrete is steam curing. When the temperature, period, or both of the steam curing process are inadequate, the effect of air-entraining (hereafter, AE) agents is lost because the warmed air trapped by the AE agent expands and escapes from the concrete. Another problem is concrete fatigue. It is well known that the fatigue lives of concrete slabs in wet conditions are much shorter than those in dry conditions. Concrete slabs are waterproofed immediately after construction, but the waterproofing can be fractured soon after opening bridges, and water can reach the concrete surface. The lifespan of concrete slabs in contact with water often depends on the fatigue of the concrete. Granulated blast furnace slag sand (hereafter, BFS) can enhance the resistance to freezing and thawing actions without using AE agents. Therefore, the resistance to freezing and thawing of concrete mixed with BFS is not damaged by steam curing. The fatigue of concrete in water is also improved by the addition of BFS. Furthermore, BFS can reduce the drying shrinkage of concrete. It is advantageous to restrict the loss of prestress in PC. This study shows that precast PC members with high durability can be manufactured when granulated blast furnace slag is used as a fine aggregate in the concrete. BFS reacts with cement hydrates. It is well known that the carbonation of concrete with ground granulated blast furnace slag (hereafter, GGBF) is much greater than that with ordinary binder. However, BFS does not accelerate the carbonation of concrete. When using granulated blast furnace slag as a fine aggregate, no disadvantage in the concrete properties is detected.

  • Mitsuharu Shiwa, Zhengwang Li, Takuya Maeshima, Yasuhiro Koda, Yasushi ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 470-477
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Wave-guided acoustic emission (AE) signals of a reinforced-concrete slab were evaluated by fatigue testing on a wheel-load machine. Two resonant AE sensors, each with a frequency of 60 kHz, were installed at both ends of a reinforcement rod used as an AE waveguides. The detected AE signals indicated the transverse-wave radiation patterns of vertical and horizontal cracks located at the interface between the concrete and the waveguide. The activity of the cumulative AE energies corresponded to the live-load deflection and vertical-strain phenomena.

  • Takashi Yamamoto, Satoshi Takaya, Toyo Miyagawa
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 478-486
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    A load carrying capacity of the reinforced concrete (RC) member is degraded by the corrosion of reinforcing steel bars due to chloride ion ingress. A lot of researches on the effect of corrosion in the longitudinal tensile reinforcing steel bars on the load carrying behavior have been available up to now. Accurate and quantitative estimation of capacity, however, is often difficult, because of the non-uniformity of corrosion in the member. Thus, a relationship between the spatial distribution of corrosion in the reinforcement including its scatter and the flexural loading capacity of RC member with such distribution of corrosion should be clarified so that the flexural capacity of corroded RC member can be estimated accurately. On the other hand, in case of the practical RC member under the corrosive environment, it should be considered that the flexural capacity often have to be derived from not a large number of inspection data on cross sectional areas of corroded reinforcements. So, in this study, a flexural loading test was performed by using RC beam specimens with the corroded tensile reinforcements provided the distribution of sectional areas. An estimation method of the flexural capacity of corroded RC beam was also shown, considering the distribution and its scatter in sectional areas of corroded reinforcements under the limited inspection data. Furthermore, the estimation of the longitudinal distribution of the cross sectional area of corroded reinforcement was performed by the spatial interpolation using Kriging method. Test results showed the yield and maximum load capacity in the corroded RC beam decreased as the corrosion rate increased. The failure mode of rupture in the reinforcement was shown in the large corrosion. The proposed estimation method was able to lead the safe evaluation of those experimental flexural capacities, determining the appropriate longitudinal characteristic value of the cross sectional area of corroded reinforcement. The flexural capacity can be also safely calculated using the characteristic value of diameters estimated by the corrosion crack width on the surface of the concrete, while the ratio of the experimental flexural capacity to the estimated one decreased as the corrosion loss increased. The distribution of bar diameters in the corroded reinforcement was able to be roughly estimated by using Kriging method. However, it was suggested that the measurement points close to the minimum bar diameter should be included to estimate the flexural capacity on the safe side.

  • Tomoki Shiotani, Hisafumi Asaue, Takahiro Nishida, Takuya Maeshima, Ya ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 487-495
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Currently, for proper maintenance of infrastructures, preventive and proactive measures for prognosis of infrastructures are preferable in comparison with reactive/corrective maintenances of structures that are highly deteriorated. This is so because vast sums are generally necessary for recovering the performance of the highly damaged structures. Therefore, prognostic maintenance must be conducted to establish economic and efficient management systems for the existing concrete infrastructures to complete their designed service life and to even extend them. Severe deterioration of aging infrastructures is currently a critical issue. In particular, the damage and deterioration of concrete slabs in bridges and highways are regarded as a critical issue worldwide. These components are often so fatigue-damaged under conditions of heavy traffic that repair and retrofit work definitely require regulating the traffic, thereby severely disrupting their function for the users. Consequently, preventive and proactive maintenances of concrete slabs that are in service are being urgently demanded for establishing the prognosis for civil engineering. To decide the maintenance systems based on the prognosis of concrete slabs, evolution of the fatigue damage and internal defects should be evaluated properly, if possible, visually. In this respect, Acoustic Emission (AE) tomography and elastic-wave tomography is under investigation and development as innovative nondestructive testing (NDT) methods. By determining the three-dimensional velocity distribution inside a slab via the above methods, the damaged or deteriorated areas are identified. Until now, regulated on-site visual inspections are only performed for the slab components of in-service infrastructures. However, the recent methods can predict the internal defects before the deteriorations physically emerge on the surface. Therefore, inspection methods to identify internal defects in concrete are to be readily implemented prior to the repair works. In the present work, a comparative study is performed during the internal progress of the fatigue damage induced by wheel-loading to identify the damaged area quantitatively via elastic-wave tomography, followed by a comparison with resultant surface crack conditions. The results show a good agreement between the predicted low-velocity zones and the damaged areas estimated by crack distributions, displacements, and strains. In particular, at locations where cracks are intensely observed, the velocities decrease below 3400 m/s. Furthermore, the areas with velocities below 2700 m/s are also observed in the slab corresponding to the attainment of the fatigue limit.

  • Katsufumi Hashimoto, Tomoki Shiotani, Takahiro Nishida, Toyoaki Miyaga ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 496-505
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Currently, it is highly important to establish economical and efficient management systems for existing concrete infrastructures, in order to fulfil their service design lives and even to extend them. Severe deterioration in aging infrastructure is currently found to be a critical issue. For repairing deteriorated and damaged structures, large budgets are necessary, but budgetary restrictions are often imposed. As a result, preventive and proactive maintenance of infrastructure is desired, and inspections by non-destructive testing (NDT) methods must be applied. In terms of damage assessment and estimation of repair and retrofit recovery in concrete structures, in addition to current NDT, innovative methods must be established. For crack repair methods applied to the existing structures, inspection techniques to assess repair installations have not yet been practically developed. There are many reports that improper repair efforts have resulted in re-deterioration. Although epoxy injection and patch repair methods are widely implemented to refill internal cracks from the concrete surface, it is found in most cases that internal defects remain unknown and potentially could lead to the re-deterioration. Therefore, inspection methods to visualize internal defects in concrete must be readily implemented as a countermeasure for repair works. In the present study, the evaluation of repair effectiveness was performed in a reinforced concrete (RC) pier and a concrete wall in an existing structure. As an innovative NDT method, elastic-wave tomography is applied to evaluate three-dimensional (3D) velocity distribution before and after the repair. Penetration of the repair material and the increase in velocity due to the repair effect are visually and quantitatively identified. Additionally, a 3D tomography technique for one-side access is newly proposed, using drill-hammring to generate an elastic wave. Accordingly, the internal quality of concrete after patch repair is successfully visualized by the elastic wave velocity distribution.

  • Akihito Yoshida, Linsheng Liu, Dong Tu, Shigenobu Kainuma, Chao-Nan Xu
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 506-514
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    This paper reports on the mechanoluminescence inspection technology we have developed and its applications. The inspection technology is expected to identify deterioration and damage, such as fatigue cracks developed on steel members of steel structures, using particular mechanoluminescence (ML) phenomenon. In field testing at an urban highway bridge currently in service, fatigue cracks in steel box girders were successfully detected using the proposed technology. In addition, using a conventional crack detection method known as magnetic particle inspection (MT), similar results were obtained in terms of crack judgment, suggesting that the reliability of the ML method is equivalent to that of the MT method. An advantage of the ML inspection method is that it does not require removing corrosion protection coating, saving labor that is necessary in the MT method. The field testing also examined the possibility of evaluating precautionary measures (repair) as another application of the ML technique. As a result, the ML technique quantitatively evaluated that detected cracking had been properly repaired (removed). It is expected that the ML technique will contribute to effective maintenance and management of infrastructures from the perspective of preventive maintenance.

  • Hiroyuki Sato, Takashi Sasaki, Masafumi Kondo, Toshihide Kobori, Aoi O ...
    原稿種別: Survey Report
    2017 年 12 巻 3 号 p. 515-525
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    This paper presents a basic investigation of the displacement monitoring of dams following earthquakes using data obtained from an SAR (Synthetic Aperture Radar) satellite with the goal of quickly assessing the damage status. As an SAR satellite does not require ground-based measurement instruments, it can carry out displacement monitoring of an entire dam body surface and can acquire data without being affected by weather conditions. This means that SAR satellites can be relied upon to contribute to displacement monitoring of dams in the aftermath of earthquakes as well as during normal operations. In this paper, we conduct a basic study for the displacement monitoring of a dam following an earthquake using data from an SAR satellite, and we report the results of a basic investigation of the assessment of the damage status of a dam following the 2016 Kumamoto Earthquake.

  • Ryo Natsuaki, Takuma Anahara, Tsuyoshi Kotoura, Yuudai Iwatsuka, Naoya ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 526-535
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    In this paper, we present experimental results of the disaster monitoring of harbor facilities using spaceborne synthetic aperture radar interferometry (InSAR). The Advanced Land Observing Satellite-2 (ALOS-2 or DAICHI-2), operated by the Japan Aerospace Exploration Agency (JAXA), carries the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2). PALSAR-2 can observe disaster areas day and night, in any weather, at a resolution of approximately 3 m. ALOS-2 PALSAR-2 has been used to measure large-scale ground deformation e.g., after earthquakes and volcanic eruptions. However, its robustness for smaller targets, such as harbor facilities, has not yet been substantiated. Here, we measured the uplift of a breakwater model made of concrete armor units, and confirmed the sensor accuracy to be better than 2 cm standard deviation. We also analyzed the damage to the Nagata and Suma ports in Kobe city, Hyogo prefecture, Japan hit by the 11th Typhoon in 2014, and detected the damaged area using interferometric coherence analysis.

  • Kazuhiro Tsuno, Yutaka Akahori, Toshiya Yui, Hiromitsu Furukawa, Anri ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 536-545
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Salt- or neutralization-induced damage of reinforced concrete structures significantly affects their durability. Because most large-scale infrastructures, such as bridges, urban tunnels, and seawalls, are made of reinforced concrete, developing efficient and accurate methods or devices for early detection of concrete structure damage is important for disaster prevention. Moreover, the cost of a life cycle of a concrete structure can be much lower if surface degradation can be detected and preventive maintenance performed.

    In this paper, we report the development status of a remote monitoring system that implements remote imaging and diagnosis of the concrete surface degradation. The system consists of a high-sensitivity spectrometer and signal analysis software.

    The first prototype of the spectrometer was developed using a large-aperture and lossless optical system and a near-infrared camera. Near infrared spectra of samples that simulated salt damage were captured and diagnosed, to analyze the system’s performance. Then, specimens of pure materials constituting concrete were measured, and their absorption spectra were analyzed. Based on the absorption spectra it was concluded that the absorption characteristics of these substances had no influence on the quantification of Friedel’s salt.

    The prototype machine for field testing has been developed. Using this machine, a series of remote measurement of surface water with up to 10m distance was conducted. And also, measurement of surface degradation on actual concrete structures has been started, to validate the approach.

    The developed system is expected to rationalize inspection of concrete structures by enabling effective imaging and objective diagnosis of degradation, which will help to clarify which parts or sections of structures need intensive inspection for preventive maintenance.

  • Takeharu Murakami, Norihito Saito, Yuichi Komachi, Kotaro Okamura, Tak ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 546-556
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    We propose a remote surface measurement system that uses a laser to inspect tunnel walls.

    To prevent accidents caused by aging parts of the transportation infrastructure, such as tunnels and bridges, the maintenance of such structures has grown in importance. Although these structures are checked by human inspectors, it is hoped that the process can be further automated through the development of remote sensing technologies.

    In this article, we focus on the detection of cracks on tunnel surfaces. As the concrete surfaces of tunnels can have many discolored areas, the precision of conventional remote inspection methods based on digital cameras is limited.

    Employing a frequency-shifted feedback (FSF) laser to overcome this difficulty, we adopt three measurement principles: reflectance imaging, 3D measurement, and spectroscopy. We have realized high spatial resolution, which is essential to our purpose. Using reflectance imaging, we have detected cracks of more than 200 μm in width on a concrete surface. Using 3D measurement with an FSF laser, we have detected as 3D shape a 0.35 mm crack on an actual concrete surface. We also have detected the presence of water on a concrete surface using 2.95 μm mid-infrared light in the laboratory.

    We discuss the use of our system to reliably detect 0.2-mm-wide cracks on the basis of experimental results. The measurement results for the reference targets and real concrete are described.

  • Shigeru Teruhi, Yo Yamaguchi, Junichi Akahani
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 557-568
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Expectations have been raised for a social infrastructure maintenance system that utilizes IoT/M2M technology. We are working to develop a water leakage detection system using wireless sensors set into the water pipes. However, radio propagation is restricted in the constrained underground environment of water pipes so how to collect the data and identify leaks is an issue. We propose a system that combines drive-by data collection and static data collection, in order to collect acoustic sensor data from a wide area effectively [1]. We also propose a random noise removal method by focusing on the constancy of the leak sound, in order to identify leaks accurately. We show the results of evaluating the effectiveness of the proposed system in tests and real fields.

  • Yasuhiro Arai, Akira Koizumi, Toyono Inakazu, Wako Kawamura
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 569-577
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    When leak sensors are actually mounted on water pipelines, they are deployed at auxiliary equipment such as gate valves and fire hydrants located every few hundred meters. The total length of the water pipelines laid throughout Japan is approximately 650,000 km. Assuming a length of several thousand kilometers for a pipeline in a given target area, the possible locations for deploying sensors can number in the tens of thousands. Mounting sensors at all the possible locations would not be efficient, either economically or from a maintenance standpoint. In a pipeline network that spreads out horizontally, it is important to ensure that the sensors are deployed in a way to maximize their effectiveness at detecting water leakages. To this end, a method is needed for objectively planning the deployment of a given number of sensors on the optimal gate valves and hydrants. This study, aimed at the optimal deployment of leak sensors in a water pipeline network, proposes a planning model applying the k-median problem, a type of mathematical optimization problem, and verifies the effectiveness of this model via case studies.

  • Mitsuru Uesaka, Yuki Mitsuya, Eiko Hashimoto, Katsuhiro Dobashi, Ryota ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 578-584
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Regular diagnosis of the structural health of infrastructure, such as bridges, is indispensable to ensure safety and reliable operation of the society. Non-destructive tests based on X-ray imaging are powerful tools to inspect the inside of a concrete structure in detail. Establishing a diagnostic method of bridges based on X-ray visualization is required to examine the internal conditions and helps in the rationalization of maintenances. We demonstrated our 950 keV X-band electron linac based X-ray source for on-site actual bridge inspection and visualized the inner structure of a bottom floor slab. For the more precise inspection of the conditions of wires and rods, we applied three-dimensional image reconstruction methods for bridge mock-up samples. Partial angle computed tomography and tomosynthesis gave cross section images of the samples with 1 mm resolution. We are planning to investigate another part of the bridge, with the 950 keV X-ray system in the near future.

  • Yoshie Otake, Yoshichika Seki, Yasuo Wakabayashi, Yoshimasa Ikeda, Tak ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 585-592
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Neutrons have the power to penetrate metals or heavy elements such as calcium, silicon, and iron. Neutrons also have high sensitivity, so they can be used to detect elements such as boron and chlorine. An accelerator-driven, compact neutron system has been developed in RIKEN for practical use on job sites.

    In this paper, a pixel imaging detector for fast neutrons with energy levels above 1 MeV is developed and used to produce images of an iron rod and air pockets through 30 cm of concrete. Also, the salt concentrations of 4 cm- and 5 cm-thick mortar blocks are measured, and a correlation diagram is obtained for up to 1 kg/m3.

  • Yoshiro Hada, Manabu Nakao, Moyuru Yamada, Hiroki Kobayashi, Naoyuki S ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 593-606
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Recently, many countries have faced serious problems associated with aging civil infrastructures such as bridges, tunnels, dams, highways and so on. Aging infrastructures are increasing year by year and suitable maintenance actions are necessary to maintain their safety and serviceability. In fact, infrastructure deterioration has caused serious problems in the past. In order to prevent accidents with civil infrastructures, supervisors must spend a lot of money to maintain the safe conditions of infrastructures. Therefore, new technologies are required to reduce maintenance costs. In 2014 the Japanese government started the Cross-Ministerial Strategic Innovation Promotion Program (SIP), and technologies for infrastructure maintenance have been studied in the SIP project [1]. Fujitsu Limited, Hokkaido University, The University of Tokyo, Nagoya Institute of Technology and Docon Co. Limited have been engaged in the SIP project to develop a bridge inspection support system using information technology and robotic technology. Our system is divided into the following two main parts: bridge inspection support robots using a two-wheeled multicopter, and an inspection data management system utilizing 3D modeling technology. In this paper, we report the bridge inspection support system developed in our SIP project.

Regular Papers
  • Teuku Faisal Fathani, Djoko Legono, Muhammad Ahnaf Alfath
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 607-616
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Landslides are natural phenomena that occur in slopes with thick layers of weathered soil or weak geological formations. High intensity of precipitation, earthquake, and human interference can cause a huge landslide disaster. To mitigate landslide risk, an appropriate investigation to determine the stability and movement mechanisms is important to predict its potential scale. This paper proposes a sensitivity analysis of depth-integrated numerical model of landslide movement by implementing solid friction and fluid friction as the shear resistance in the constitutive systems. The hyperconcentrated solid-liquid mixture flow model and Voellmy-fluid friction model are employed in the solid friction and fluid friction mechanism, whereas the Mohr-Coulomb model is used in the solid friction mechanism. In order to analyze model characteristics and sensitivity to the inputted parameters, the parametric studies on an imaginary slope were examined. The results show that the internal friction angle among input data strongly affects the runout distance and moving velocity. The Voellmy-fluid friction model produces more lateral tendency and wider deposit in transversal directions of landslide compared to other models. The numerical model along with three constitutive equations of shear resistance was applied to the Bishamon Landslide. The hyperconcentrated solid-liquid mixture flow model and Mohr-Coulomb model yield a good agreement with the actual deposition area, whereas the Voellmy-fluid friction model produces more lateral tendency in transversal directions. The calculated runout distance reaches more than 350 m and 10.3 to 13.9 m/s of maximum velocity.

  • Fahmi Hidayat, Pitojo T. Juwono, Agus Suharyanto, Alwafi Pujiraharjo, ...
    原稿種別: Paper
    2017 年 12 巻 3 号 p. 617-630
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Wlingi and Lodoyo reservoirs in the Brantas River basin, Indonesia, provide numerous benefits including reliable irrigation water supply, flood control, power generation, fisheries and recreation. The function of both reservoirs particularly in relation to flood control has declined due to severe sedimentation that has reduced their storage capacities. The sedimentation in Wlingi and Lodoyo reservoirs is mainly caused by sediment inflow from the areas most affected by ejecta from eruptions of Mt. Kelud, one of the most active volcanoes in Indonesia. The main objective of this research is to assess the sedimentation problem in Wlingi and Lodoyo reservoirs, particularly as they are affected by eruptions of Mt Kelud. We performed reservoir bathymetric surveys and field surveys after the most recent eruption of Mt. Kelud in February 2014 and compared the results with surveys undertaken before the eruption. The assessment revealed that both reservoirs were severely affected by the 2014 eruption. The effective storage capacity of Wlingi reservoir in March 2013 was 2.01 Mm3 and the survey in May 2015 indicated that the effective storage of Wlingi reservoir had decreased to 1.01 Mm3. Similarly, the effective storage capacity of Lodoyo reservoir in March 2013 was 2.72 Mm3, reduced to 1.33 Mm3 in May 2015. These findings underpin the analysis of the impacts of the secondary disaster due to reservoir sedimentation following the volcanic eruption and the implications for mitigating and managing the risks for sustainable use of reservoirs to control floods, supply water, generate electricity, etc. To cope with the extreme sedimentation problem in Wlingi and Lodoyo reservoirs, diverse sediment management strategies have been applied in these reservoirs and their catchments. However sediment disaster management strategies for both reservoirs, an integral part of the Mt. Kelud Volcanic Disaster Mitigation Plan, require continuous maintenance and recurrent operations, and ongoing evaluation and improvement.

  • Miki Ozeki, Kan Shimazaki, Taiyoung Yi
    原稿種別: Material
    2017 年 12 巻 3 号 p. 631-638
    発行日: 2017/06/01
    公開日: 2018/11/01
    ジャーナル 認証あり

    Many educational activities and disaster drills are conducted for the purpose of developing disaster prevention consciousness. It is necessary to develop a standardized psychological scale to measure disaster prevention consciousness; this would help evaluate the effect of activities that improve disaster prevention consciousness. To do this, a qualitative study using a Constructivist Grounded Theory Approach was conducted. First, elements of disaster prevention consciousness were explored through one-hour interviews with a total of ten disaster prevention professionals. They responded to six questions on the characteristics and behaviors of a person who seemed to possess high disaster prevention consciousness. The study yielded six elements in knowledge (ex. “Reality of disaster”), eight elements in behavior (ex. “Preparation for disaster”), and ten psychological elements (ex. “Over-reliance on one measure against disasters,” “Prediction and analysis of situations,” and “Taking a comprehensive view”). A new anti-disaster consciousness model was developed based on these elements.

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