A massive earthquake often causes long-lasting geological issues, and the May 12th 2008 Wenchuan ... more A massive earthquake often causes long-lasting geological issues, and the May 12th 2008 Wenchuan Earthquake was no exception. To quickly cope with ongoing problems, archiving past case histories is certainly necessary. This paper provides case histories from the 2005 Kashmir Earthquake, Pakistan, and the 2004 Mid-Niigata Earthquake, Japan, in which tho ough monitoring of landforms has highlighted cause-and-effect sequence of events in the affected areas, and provides a basis for the recommendation of effective rehabilitation.
Japanese Geotechnical Society Special Publication, 2016
The major problems associated with liquefaction-induced ground subsidence are tilting of houses, ... more The major problems associated with liquefaction-induced ground subsidence are tilting of houses, buckling of roads, lifelines cut off, etc. For the mitigation and preparedness over the liquefaction-induced damage, a detailed study on prediction of ground subsidence for future earthquake is important. On the 11 th of March 2011, the Off the Pacific Coast of Tohoku Earthquake (MW=9) hit Japan and caused severe liquefaction in Urayasu City, Chiba Prefecture. In this study, in order to investigate the relationship between liquefaction potential, PL, and liquefaction-induced subsidence which occurred in the 2011 earthquake, liquefaction assessment is first carried out by using a number of boreholes and relevant soil test data from Urayasu city. Then, the liquefaction-induced road subsidence is extracted from a set of the Digital Surface Models (DSMs) from airborne LiDAR (Light Detection And Ranging) surveys before (2006) and after (2011) the earthquake. The extracted subsidence from the DSMs indicates that the liquefaction-induced road subsidence is larger for the residential roads than that of the main roads, thus the relationship between PL and road subsidence is different for each type of road. Finally, an attempt is made to apply the obtained PL and road subsidence relations to attain a unique hazard map for Urayasu city.
The distance to the surface rupture zone has been commonly regarded as an important influencing f... more The distance to the surface rupture zone has been commonly regarded as an important influencing factor in the evaluation of earthquake-triggered landslide susceptibility. However, the obvious surface rupture zones usually do not occur in some buried-fault earthquake cases, which means information about the distance to the surface rupture is lacking. In this study, a new influencing factor named coseismic ground deformation was added to remedy this shortcoming. The Mid-Niigata prefecture earthquake was regarded as the study case. To select a more suitable model for generating the landslide susceptibility map, three commonly used models named logistic regression (LR), artificial neural network (ANN), and support vector machine (SVM) were also conducted to assess landslide susceptibility. The performances of these three models were evaluated with the receiver operating characteristic curve. The calculated results showed that the ANN model has the highest area under the curve (AUC) value of 0.82. As the earthquake triggered more landslides in the epicenter area, which makes it more prone to landslides in further earthquakes, the susceptibility analysis at two different mapping scales (the whole study area and the epicenter area) was also applied.
International journal of engineering and technologies, Nov 1, 2018
The present paper reports an experimental study on the effect of finite clamping on static and dy... more The present paper reports an experimental study on the effect of finite clamping on static and dynamic characteristics of cantilever beam. The experiment is carried out with two different beams, each of which is clamped at two different locations resulting in two different geometry settings. Under each of these four settings, specimen is clamped under two different torque ratings giving rise to different finite clamping effect. Under the eight settings, coordinates of tip point under static loading are measured directly using scales and plumb at each load step; whereas, complete deflection profiles of loaded beam under each static load step are obtained through postprocessing of images captured during experimentation. Such image processing is carried out manually using AutoCAD ® and in-built AutoLISP ® software. Strain measurements at each static load step are carried out by using strain gauge, a universal data acquisition system and the associated Catman Easy ® software. To obtain loaded free vibration characteristics, loaded beam under each setting is disturbed by a rubber hammer and its dynamic response is recorded from strain gauge signal through Catman Easy ® software. These dynamic strain readings of loaded beam are post-processed and FFT plots are generated in MATLAB ® software and first two loaded natural frequencies of beam under each setting are obtained. Finally, effects of clamping torques on the static strain and deflection results and loaded natural frequencies for beam settings with the four different thickness to length ratios are reported in a suitable manner. The result reported may be useful as ready reference to develop a theoretical model of clamped beam like structures incorporating the effect of finite clamping.
Foundation Engineering: Current Principles and Practices, Dec 1, 1989
A simplified approach for the transient dynamic response analysis of embedded multiple rigid foun... more A simplified approach for the transient dynamic response analysis of embedded multiple rigid foundations is presented. The approach is based on approximate time-domain formulations of the interaction force acting along the side and of motions transmitted from one foundation body to another. All of those formulations are developed within the Winkler's hypothesis. Some numerical examples are given to demonstrate the approach. It is confirmed that the approach is efficient in computation and can accommodate the nonlinear mechanism in a rational manner.
The impact of a large inland earthquake is profound because of its intense shakes and the associa... more The impact of a large inland earthquake is profound because of its intense shakes and the associated landslides and debris flows. The quake-induced landslides and debris flow are often the most devastating secondary effect of an earthquake in terms of all kinds of losses, causing long-lasting problems in post-quake rehabilitation activities. An earthquake-induced landslide is just one scene of ever-evolving mountain topography. Therefore, studying terrain dynamics is vital to comprehend the possibility of hazards and propose and apply rational rehabilitation tactics. Though serious, the damage caused by the Mid-Niigata Prefecture Earthquake of October 23, 2004, has given us a rare opportunity to study the landform changes caused by an earthquake that hit an active-folding mountainous terrain. To deal with rehabilitation problems in a scientific manner, a research program, "Earthquake damage in active-folding areas: the creation of a comprehensive data archive and suggestions for its application to remedial measures for civil-infrastructure systems," was set up getting the Special Coordination Funds for Promoting Science and Technology, Ministry of Education, Culture, Sports, Science and Technology (MEXT). This article reviews some significant findings obtained through this project and even beyond it. The results show that essential aspects of quake-caused problems were linked to deep-seated tectonic displacements, namely the internal driving stress field associated with earthquakes to evolve the active-folding terrain.
On March 11, 2011, a large earthquake of Mw 9.0 shook northeastern Japan and caused severe liquef... more On March 11, 2011, a large earthquake of Mw 9.0 shook northeastern Japan and caused severe liquefaction-induced damage over a wide area of reclaimed lands along the coast of Tokyo Bay. Although regional mapping of the liquefaction hazard had been performed in many automounts bodies in Japan, it seems that the maps were not effectively used on all fronts of disaster-prevention management, because the maps only provide liquefaction susceptibilities and little quantitative information on how seriously the ground might deform in a scenario earthquake, which is absolutely necessary information for discussing what-if scenarios. Konagai et al. (2013) conducted airborne LiDAR surveys to obtain liquefaction-induced ground deformations over the northeastern stretch of the Tokyo Bay shore area, including Urayasu City, where approximately 85% of the city area was heavily liquefied. Meanwhile, the authors have developed a geotechnical database for liquefaction risk assessments, compiling all the available borehole logs and soil testing data provided by Urayasu City (2012). Given the potential risk of re-liquefaction in a future scenario earthquake, it is an overriding priority to develop a knowledge-sharing liquefaction hazard map reflecting precise records from the past, such as liquefaction-induced ground subsidence and liquefaction-related damage. This paper attempts to assess the liquefaction-induced damage risk on road network, examining the relationship between the liquefaction potential index and the actual ground subsidence. For this purpose, firstly, the spatial distribution of the liquefaction potential (P L) was estimated over Urayasu City based on the above-mentioned geotechnical database developed by the authors. Secondly, the spatial distribution of the P L values and the actual liquefaction-induced road subsidence confirmed through air-born LiDAR surveys were compared to develop an empirical rule for estimating the potential road subsidence in a scenario earthquake. This empirical rule was found to describe the actual damage to roads and manholes in a satisfactory manner. Therefore, it is expected that a risk map, developed on the basis of this empirical rule, will not only help to assess liquefaction-induced damage, but also to design countermeasures against the what-if scenarios of liquefaction.
Based on solid evidence, scientists attribute the global warming trend observed since the mid-twe... more Based on solid evidence, scientists attribute the global warming trend observed since the mid-twentieth century to the human expansion of the "greenhouse effect." Extreme rainfall events have become more frequent worldwide, resulting in hydro-meteorological hazards creating more deaths and devastation. One of the most remarkable disasters of rain-induced rapid long-traveling landslides (RRLL) in Sri Lanka took place at Aranayake, 70 km east of Colombo, in 2016 (JICA Survey Team (2016), Survey results of Aranayake Disaster, JICA. URL: https://www.jica.go.jp/srilanka/english/office/topics/ c8h0vm00006ufwhl-att/160720.pdf [Last accessed: April 14, 2020]). The fluidized landslide mass ran over an about 2 km distance claiming the lives of 125 people. This tragic event highlighted the importance of reliable early warning and disaster management mechanisms even more than ever because the presence of these hidden unstable soil masses, as well as their run-out distances, are hardly predicted. Once they start sliding, it is almost impossible to stop them. Since 2020 (after the preceding period of 2019), both the National Building Research Organization, Sri Lanka (NBRO) and the International Consortium on Landslides (ICL) have jointly started a new 5-year research project, "Development of early warning technology of Rain-induced Rapid and Long-travelling Landslides (Project RRLL)," within the framework of SATREPS. SATREPS, standing for "Science and Technology Research Partnership for Sustainable Development," is a Japanese government program promoting international joint research. This article reports on the outline of the project, including its background, goals, plans of plots for developing critical technologies for the early warning system, etc.
PROCEEDINGS OF TUNNEL ENGINEERING, JSCE, Dec 3, 1998
This paper presents the method to place an Isolation device on the top of center columns in shiel... more This paper presents the method to place an Isolation device on the top of center columns in shield-driven tunnels with multi-circular cross section to reduce shear force and bending moment at the columns and the segments around the connection to the columns. A series of static FEM analyses were conducted to examine the effectiveness of the device, and then it was found that the application of some seismic isolation devices such as rubber bearings to which additional devices to decrease the rotational stiffness was installed, would be practical with a high performance.
Simulation of the in situ behavior of pile foundation is necessary in the seismic design and asse... more Simulation of the in situ behavior of pile foundation is necessary in the seismic design and assessment of piles for target structural integrity and performance during earthquakes. Having the mere presence of the soil and the pile in this foundation system, the complex behavior of piles is generally captured by the soil-pile interaction. In this research, a simple parameter called the active pile length, L a, which is reflective of the deformation of pile relative to the stiffness of the soil, is explored to describe the ultimate lateral resistance of the soil. The idea is based upon the deformation of flexible piles commonly used in engineering practice. When piles are induced by a lateral load, the pile deforms significantly in the region near the ground surface and decreases with increasing depth. This region of significant deformation down to the negligible point along the pile depth is defined as the active pile length, L a. During the event of nonlinear excitation, a soil wedge is formed in the passive region along this active pile length. This soil wedge is indicative of the ultimate side soil resistance, and thus can be inferred to be described by L a. To simply investigate, a simple plane strain condition using 2-D finite element method in nonlinear analysis is done to obtain the behavior response of a single pile embedded in a homogeneous soft soil. The elasto-plastic behavior of the soil is modeled using the subloading t ij model and the pile is modeled as a 2-D continuum based beam element. Deformation of the pile and corresponding surrounding lateral soil deformation are analyzed. The potential of this simple concept of active pile length to describe the nonlinear response of piles embedded on soft soils is presented for more practical approach in the seismic design and assessment of piles.
A massive earthquake often causes long-lasting geological issues, and the May 12th 2008 Wenchuan ... more A massive earthquake often causes long-lasting geological issues, and the May 12th 2008 Wenchuan Earthquake was no exception. To quickly cope with ongoing problems, archiving past case histories is certainly necessary. This paper provides case histories from the 2005 Kashmir Earthquake, Pakistan, and the 2004 Mid-Niigata Earthquake, Japan, in which tho ough monitoring of landforms has highlighted cause-and-effect sequence of events in the affected areas, and provides a basis for the recommendation of effective rehabilitation.
Japanese Geotechnical Society Special Publication, 2016
The major problems associated with liquefaction-induced ground subsidence are tilting of houses, ... more The major problems associated with liquefaction-induced ground subsidence are tilting of houses, buckling of roads, lifelines cut off, etc. For the mitigation and preparedness over the liquefaction-induced damage, a detailed study on prediction of ground subsidence for future earthquake is important. On the 11 th of March 2011, the Off the Pacific Coast of Tohoku Earthquake (MW=9) hit Japan and caused severe liquefaction in Urayasu City, Chiba Prefecture. In this study, in order to investigate the relationship between liquefaction potential, PL, and liquefaction-induced subsidence which occurred in the 2011 earthquake, liquefaction assessment is first carried out by using a number of boreholes and relevant soil test data from Urayasu city. Then, the liquefaction-induced road subsidence is extracted from a set of the Digital Surface Models (DSMs) from airborne LiDAR (Light Detection And Ranging) surveys before (2006) and after (2011) the earthquake. The extracted subsidence from the DSMs indicates that the liquefaction-induced road subsidence is larger for the residential roads than that of the main roads, thus the relationship between PL and road subsidence is different for each type of road. Finally, an attempt is made to apply the obtained PL and road subsidence relations to attain a unique hazard map for Urayasu city.
The distance to the surface rupture zone has been commonly regarded as an important influencing f... more The distance to the surface rupture zone has been commonly regarded as an important influencing factor in the evaluation of earthquake-triggered landslide susceptibility. However, the obvious surface rupture zones usually do not occur in some buried-fault earthquake cases, which means information about the distance to the surface rupture is lacking. In this study, a new influencing factor named coseismic ground deformation was added to remedy this shortcoming. The Mid-Niigata prefecture earthquake was regarded as the study case. To select a more suitable model for generating the landslide susceptibility map, three commonly used models named logistic regression (LR), artificial neural network (ANN), and support vector machine (SVM) were also conducted to assess landslide susceptibility. The performances of these three models were evaluated with the receiver operating characteristic curve. The calculated results showed that the ANN model has the highest area under the curve (AUC) value of 0.82. As the earthquake triggered more landslides in the epicenter area, which makes it more prone to landslides in further earthquakes, the susceptibility analysis at two different mapping scales (the whole study area and the epicenter area) was also applied.
International journal of engineering and technologies, Nov 1, 2018
The present paper reports an experimental study on the effect of finite clamping on static and dy... more The present paper reports an experimental study on the effect of finite clamping on static and dynamic characteristics of cantilever beam. The experiment is carried out with two different beams, each of which is clamped at two different locations resulting in two different geometry settings. Under each of these four settings, specimen is clamped under two different torque ratings giving rise to different finite clamping effect. Under the eight settings, coordinates of tip point under static loading are measured directly using scales and plumb at each load step; whereas, complete deflection profiles of loaded beam under each static load step are obtained through postprocessing of images captured during experimentation. Such image processing is carried out manually using AutoCAD ® and in-built AutoLISP ® software. Strain measurements at each static load step are carried out by using strain gauge, a universal data acquisition system and the associated Catman Easy ® software. To obtain loaded free vibration characteristics, loaded beam under each setting is disturbed by a rubber hammer and its dynamic response is recorded from strain gauge signal through Catman Easy ® software. These dynamic strain readings of loaded beam are post-processed and FFT plots are generated in MATLAB ® software and first two loaded natural frequencies of beam under each setting are obtained. Finally, effects of clamping torques on the static strain and deflection results and loaded natural frequencies for beam settings with the four different thickness to length ratios are reported in a suitable manner. The result reported may be useful as ready reference to develop a theoretical model of clamped beam like structures incorporating the effect of finite clamping.
Foundation Engineering: Current Principles and Practices, Dec 1, 1989
A simplified approach for the transient dynamic response analysis of embedded multiple rigid foun... more A simplified approach for the transient dynamic response analysis of embedded multiple rigid foundations is presented. The approach is based on approximate time-domain formulations of the interaction force acting along the side and of motions transmitted from one foundation body to another. All of those formulations are developed within the Winkler's hypothesis. Some numerical examples are given to demonstrate the approach. It is confirmed that the approach is efficient in computation and can accommodate the nonlinear mechanism in a rational manner.
The impact of a large inland earthquake is profound because of its intense shakes and the associa... more The impact of a large inland earthquake is profound because of its intense shakes and the associated landslides and debris flows. The quake-induced landslides and debris flow are often the most devastating secondary effect of an earthquake in terms of all kinds of losses, causing long-lasting problems in post-quake rehabilitation activities. An earthquake-induced landslide is just one scene of ever-evolving mountain topography. Therefore, studying terrain dynamics is vital to comprehend the possibility of hazards and propose and apply rational rehabilitation tactics. Though serious, the damage caused by the Mid-Niigata Prefecture Earthquake of October 23, 2004, has given us a rare opportunity to study the landform changes caused by an earthquake that hit an active-folding mountainous terrain. To deal with rehabilitation problems in a scientific manner, a research program, "Earthquake damage in active-folding areas: the creation of a comprehensive data archive and suggestions for its application to remedial measures for civil-infrastructure systems," was set up getting the Special Coordination Funds for Promoting Science and Technology, Ministry of Education, Culture, Sports, Science and Technology (MEXT). This article reviews some significant findings obtained through this project and even beyond it. The results show that essential aspects of quake-caused problems were linked to deep-seated tectonic displacements, namely the internal driving stress field associated with earthquakes to evolve the active-folding terrain.
On March 11, 2011, a large earthquake of Mw 9.0 shook northeastern Japan and caused severe liquef... more On March 11, 2011, a large earthquake of Mw 9.0 shook northeastern Japan and caused severe liquefaction-induced damage over a wide area of reclaimed lands along the coast of Tokyo Bay. Although regional mapping of the liquefaction hazard had been performed in many automounts bodies in Japan, it seems that the maps were not effectively used on all fronts of disaster-prevention management, because the maps only provide liquefaction susceptibilities and little quantitative information on how seriously the ground might deform in a scenario earthquake, which is absolutely necessary information for discussing what-if scenarios. Konagai et al. (2013) conducted airborne LiDAR surveys to obtain liquefaction-induced ground deformations over the northeastern stretch of the Tokyo Bay shore area, including Urayasu City, where approximately 85% of the city area was heavily liquefied. Meanwhile, the authors have developed a geotechnical database for liquefaction risk assessments, compiling all the available borehole logs and soil testing data provided by Urayasu City (2012). Given the potential risk of re-liquefaction in a future scenario earthquake, it is an overriding priority to develop a knowledge-sharing liquefaction hazard map reflecting precise records from the past, such as liquefaction-induced ground subsidence and liquefaction-related damage. This paper attempts to assess the liquefaction-induced damage risk on road network, examining the relationship between the liquefaction potential index and the actual ground subsidence. For this purpose, firstly, the spatial distribution of the liquefaction potential (P L) was estimated over Urayasu City based on the above-mentioned geotechnical database developed by the authors. Secondly, the spatial distribution of the P L values and the actual liquefaction-induced road subsidence confirmed through air-born LiDAR surveys were compared to develop an empirical rule for estimating the potential road subsidence in a scenario earthquake. This empirical rule was found to describe the actual damage to roads and manholes in a satisfactory manner. Therefore, it is expected that a risk map, developed on the basis of this empirical rule, will not only help to assess liquefaction-induced damage, but also to design countermeasures against the what-if scenarios of liquefaction.
Based on solid evidence, scientists attribute the global warming trend observed since the mid-twe... more Based on solid evidence, scientists attribute the global warming trend observed since the mid-twentieth century to the human expansion of the "greenhouse effect." Extreme rainfall events have become more frequent worldwide, resulting in hydro-meteorological hazards creating more deaths and devastation. One of the most remarkable disasters of rain-induced rapid long-traveling landslides (RRLL) in Sri Lanka took place at Aranayake, 70 km east of Colombo, in 2016 (JICA Survey Team (2016), Survey results of Aranayake Disaster, JICA. URL: https://www.jica.go.jp/srilanka/english/office/topics/ c8h0vm00006ufwhl-att/160720.pdf [Last accessed: April 14, 2020]). The fluidized landslide mass ran over an about 2 km distance claiming the lives of 125 people. This tragic event highlighted the importance of reliable early warning and disaster management mechanisms even more than ever because the presence of these hidden unstable soil masses, as well as their run-out distances, are hardly predicted. Once they start sliding, it is almost impossible to stop them. Since 2020 (after the preceding period of 2019), both the National Building Research Organization, Sri Lanka (NBRO) and the International Consortium on Landslides (ICL) have jointly started a new 5-year research project, "Development of early warning technology of Rain-induced Rapid and Long-travelling Landslides (Project RRLL)," within the framework of SATREPS. SATREPS, standing for "Science and Technology Research Partnership for Sustainable Development," is a Japanese government program promoting international joint research. This article reports on the outline of the project, including its background, goals, plans of plots for developing critical technologies for the early warning system, etc.
PROCEEDINGS OF TUNNEL ENGINEERING, JSCE, Dec 3, 1998
This paper presents the method to place an Isolation device on the top of center columns in shiel... more This paper presents the method to place an Isolation device on the top of center columns in shield-driven tunnels with multi-circular cross section to reduce shear force and bending moment at the columns and the segments around the connection to the columns. A series of static FEM analyses were conducted to examine the effectiveness of the device, and then it was found that the application of some seismic isolation devices such as rubber bearings to which additional devices to decrease the rotational stiffness was installed, would be practical with a high performance.
Simulation of the in situ behavior of pile foundation is necessary in the seismic design and asse... more Simulation of the in situ behavior of pile foundation is necessary in the seismic design and assessment of piles for target structural integrity and performance during earthquakes. Having the mere presence of the soil and the pile in this foundation system, the complex behavior of piles is generally captured by the soil-pile interaction. In this research, a simple parameter called the active pile length, L a, which is reflective of the deformation of pile relative to the stiffness of the soil, is explored to describe the ultimate lateral resistance of the soil. The idea is based upon the deformation of flexible piles commonly used in engineering practice. When piles are induced by a lateral load, the pile deforms significantly in the region near the ground surface and decreases with increasing depth. This region of significant deformation down to the negligible point along the pile depth is defined as the active pile length, L a. During the event of nonlinear excitation, a soil wedge is formed in the passive region along this active pile length. This soil wedge is indicative of the ultimate side soil resistance, and thus can be inferred to be described by L a. To simply investigate, a simple plane strain condition using 2-D finite element method in nonlinear analysis is done to obtain the behavior response of a single pile embedded in a homogeneous soft soil. The elasto-plastic behavior of the soil is modeled using the subloading t ij model and the pile is modeled as a 2-D continuum based beam element. Deformation of the pile and corresponding surrounding lateral soil deformation are analyzed. The potential of this simple concept of active pile length to describe the nonlinear response of piles embedded on soft soils is presented for more practical approach in the seismic design and assessment of piles.
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Papers by Kazuo Konagai