Keshab Sharma - Academia.edu (original) (raw)
Papers by Keshab Sharma
Numerous centrifuge experiments (e.g., Rosebrook 2001; Ugalde et al. 2007; Gajan and Kutter 2008;... more Numerous centrifuge experiments (e.g., Rosebrook 2001; Ugalde et al. 2007; Gajan and Kutter 2008; Deng et al. 2012; Hakhamaneshi et al. 2012; Liu et al. 2013; Allmond and Kutter 2014; Loli et al. 2014) and 1g shake-table experiments (e.g., Shirato et al. 2008; Drosos et al. 2012; Antonellis et al. 2015; Tsatsis and Anastasopoulos 2015) have demonstrated that rocking shallow foundations can be designed to provide re-centering and energy dissipation with little damage to the foundation or superstructure. Each research team listed above studied specific response aspects by varying soil profiles, structural properties and ground motions. As a result of this cumulative body of research, the concept of a controlled share of ductility demand between the superstructure and the foundation as a key ingredient for a rationale and integrated approach to the seismic design of foundations and structures has been gaining acceptance within the research and practicing earthquake engineering communit...
GeoHazards, 2021
Kathmandu Valley lies in an active tectonic zone, meaning that earthquakes are common in the regi... more Kathmandu Valley lies in an active tectonic zone, meaning that earthquakes are common in the region. The most recent was the Gorkha Nepal earthquake, measuring 7.8 Mw. Past earthquakes caused soil liquefaction in the valley with severe damages and destruction of existing critical infrastructures. As for such infrastructures, the road network, health facilities, schools and airports are considered. This paper presents a liquefaction susceptibility map. This map was obtained by computing the liquefaction potential index (LPI) for several boreholes with SPT measurements and clustering the areas with similar values of LPI. Moreover, the locations of existing critical infrastructures were reported on this risk map. Therefore, we noted that 42% of the road network and 16% of the airport area are in zones of very high liquefaction susceptibility, while 60%, 54%, and 64% of health facilities, schools and colleges are in very high liquefaction zones, respectively. This indicates that most of...
An earthquake of moment magnitude (Mw) 7.8 struck Nepal at 06:11 UTC on April 25, 2015. A field r... more An earthquake of moment magnitude (Mw) 7.8 struck Nepal at 06:11 UTC on April 25, 2015. A field reconnaissance was carried out immediately after the main shock. This paper presents the accelerograms and the geology of Nepal. The acceleration response spectra of the motions at the valley show a prominent amplification at the period of 5 sec. This paper describes the effects of local geology and topography on the damage severity during the earthquake. The damage patterns illustrate the strong influence of local geology conditions on the severity of the damage at many places, like soil amplification in Gongabu, Machhapokhari, Ramkot, Purano Naikap, areas along the major rivers in Kathmandu Valley with loose alluvium deposits, and ridge effects on the Swayambhu Nath hill and Chautara. The effect of low frequency amplification caused by the Kathmandu Valley basin is evident from the severe damage to well-designed tall buildings in Kathmandu. Severe damages including ground fissures and l...
Earthquake Spectra
Several experimental studies have shown that rocking shallow foundations have beneficial seismic ... more Several experimental studies have shown that rocking shallow foundations have beneficial seismic performance features: recentering and energy dissipation with little damage. A new publicly available database, “FoRDy” (Foundation Rocking—Dynamic), summarizes the results of dynamic physical model tests of single-degree-of-freedom-like structures supported on rocking foundations. It contains data from five centrifuge and three 1- g shaking table test series that were conducted at experimental facilities in the United States, Greece, and Japan. The database includes 200 model “case histories” that span a wide range of model sizes, soil and structure properties, and seismic excitations. It is compiled as the first step toward building a comprehensive dynamic rocking foundation database, and it has the potential to grow in the future. To illustrate its usefulness, the data are used to show example correlations between the peak drift ratio demand and selected ground motion intensity measur...
Journal of Earthquake Engineering
ABSTRACT This paper reports the structural failures and collapse of heritage structures in Kathma... more ABSTRACT This paper reports the structural failures and collapse of heritage structures in Kathmandu Valley, Nepal, during the 2015 Nepal earthquake, and presents preliminary findings regarding the causes of failures and collapses. Field reconnaissance was carried out immediately after the main shock (Mw 7.8) on April 25 and the strongest aftershock (Mw 7.3) on May 12. It was observed that the performance of heritage structures was influenced by the combination of several factors, including structural and architecture type, configuration and structural deficiency, local site effects and ground-motion characteristics, age and maintenance level, material quality, etc. It was observed that dome structures performed very well, followed by pagoda (tiered temple), and shikhara structures were found as the most vulnerable structures. Moreover, it was observed that structures that had been seismically retrofitted and well maintained appeared to perform well. Some recommendations are made to improve the seismic performance of the heritage structures in Kathmandu Valley.
Canadian Geotechnical Journal
This paper presents a field test program of a large-scale soil-footing-structure system designed ... more This paper presents a field test program of a large-scale soil-footing-structure system designed with a rocking foundation in a cohesive soil, to examine the behaviour of the system and to provide case histories for possible performance-based seismic design of foundations. The rocking system was subjected to slow cyclic loadings at various drift ratios up to 7%. Twenty-four tests were conducted for foundations with varying initial factors of safety against the bearing failure, loading directions, rotation amplitudes, and embedment. A geotechnical investigation was carried out to determine soil properties before and after the experiments. The system performance indices, such as damping, stiffness, settlement and re-centering capability, were quantified and compared to the published literature. Field test results showed that the strength and unit weight of soils at footing edges were increased due to rocking, for the present cohesive soil. The rocking moment capacity increased slightl...
Geomatics, Natural Hazards and Risk
The Gorkha earthquake on April 25, 2015 had significantly affected the livelihood of people and t... more The Gorkha earthquake on April 25, 2015 had significantly affected the livelihood of people and the overall economy in Nepal. The earthquake had caused damage to about half a million private and public buildings, apart from damage to other infrastructures including schools, hospitals, roads, hydropower, irrigation canals, etc. The earthquake had affected the lives of 8 million people. With significant numbers of actors and stakeholders involved in the reconstruction process, no significant relief has reached the ground or is observable even after 3 years of the disaster. The government has formed National Reconstruction Authority (NRA) as the focal authority for the reconstruction process which is leading the reconstruction process with line agencies and other stakeholders. The longitudinal study was carried out through semi-structured interviews with the engineers working under NRA, local people and social mobilizer, group discussions, and field observation from June 2015 to August 2016 focusing on challenges for timely and quality reconstruction. The research also reviews the experiences from past events in similar social and political condition. This study concludes that the situation was the result of larger institutional gaps as the absence of local government, lack of coordination, bureaucratic hurdles and political transition, weak governance and cross-cutting issues as accessibility, manpower shortage, knowledge gap and other socio-cultural aspects. Authors supplement that the good governance and strategic incorporation of social and cultural aspects of reconstructions along with the technical cross-cutting issues like skilled labour, resources availability and construction knowledge could help to expedite the reconstruction process.
Journal of the Institute of Engineering
An earthquake of moment magnitude (Mw ) 7.8 struck the central Nepal at 11:56 am on April 25, 20... more An earthquake of moment magnitude (Mw ) 7.8 struck the central Nepal at 11:56 am on April 25, 2015. More than 9,000 people were killed and thousands of residential buildings, and hundreds other structures were also destroyed. An aftershock of moment magnitude (Mw ) 7.3 hit northeast of Kathmandu on May 12 after 17 days of main shock which caused additional damages. Immediately after the earthquake, authors undertook a field investigation and visited the affected areas. Strong motion records from both earthquakes and their impacts on structures as well as geotechnical issues are presented in this paper. Most of the structures in Nepal are made of adobe, unreinforced masonry, and reinforced concrete. Failure mechanisms of those buildings are briefly explained in this paper. Geotechnical aspects such as soil liquefaction, slope failures, settlement and lateral spreading, and site amplification effects that considerably influenced the damage patterns at many areas are briefly discussed...
Journal of the Institute of Engineering
The Gorkha earthquake on April 25, 2015 has significantly affected the livelihood of people and o... more The Gorkha earthquake on April 25, 2015 has significantly affected the livelihood of people and overall economy in Nepal, causing severe damage and destruction in central Nepal including nation's capital. 800 thousand buildings were affected leaving 8 million people homeless. Challenge of reconstruction of optimum 800 thousand houses is arduous for Nepal Government in background of its turmoil political scenario and weak governance apart from its difficult geographical terrain. Albeit, with significant number of stakeholders involved in the reconstruction process, no appreciable progress has seen to the ground till date, which is reflected over the frustration of affected people. In order to identify factors hindering timely and quality reconstruction, this research has brought basic arguments and ideas prospected by different actors involved in the process. Methodology of the study is comprised with semi structured interviews with social mobilizers, engineers working in the fie...
International Journal of Geotechnical Engineering
Abstract The Gorkha (Nepal) earthquake of the moment magnitude M w 7.8 occurred on 25 April 2015,... more Abstract The Gorkha (Nepal) earthquake of the moment magnitude M w 7.8 occurred on 25 April 2015, with the epicenter 77 km north-west of Kathmandu at a focal depth of 13 km. After the main shock of the earthquake, a field investigation was carried out in the Kathmandu Valley to collect case histories of geotechnical and structural damages. This paper provides the observations of liquefaction case histories and the liquefaction potential assessment based on Standard Penetration Tests for liquefied and non-liquefied sites were performed. Recorded ground motions from the event are presented and the local site effect on the occurrence of liquefaction is described briefly. Observed liquefaction case studies are presented. Ejected soils at liquefied sites were collected and the particle size distributions of ejected soils were analysed. SPT blow counts and the soil profiles at eight liquefied and non-liquefied sites were obtained. The factors of safety against liquefaction with depth and liquefaction potential index of the eight sites were estimated and compared with observed liquefaction areas during Gorkha earthquake. The liquefaction potential indices obtained from the analysis were found to be consistent with the field observation.
Soils and Foundations
Abstract This study investigates the effects of wetting and drying cycles, known as slaking, on t... more Abstract This study investigates the effects of wetting and drying cycles, known as slaking, on the strength-displacement characteristics of crushed mudstone. A series of direct shear tests was conducted by simulating cyclic wetting and drying under different stress conditions using a modified direct shear apparatus. The effects of the stress ratio, the density of specimen, the initial water content before wetting, the slaking index, and the number of wetting and drying cycles on the test results was investigated. Experiments were also performed on less-slakable materials, including crushed sand stone, silica sand and glass beads, to compare the results with the crushed mudstone. Considerable creep displacement on the crushed mudstones was observed during both drying and wetting phases under the constant shear stress conditions. The creep displacement during the drying was more significant than during the wetting phase. The creep displacement accumulated with progressive wetting and drying cycles. The drying-induced displacement was observed when the water content became smaller than the amount of water absorption of the mudstone specimens. Correspondingly, a gradual decrease of the peak stress ratio was observed with the number of wetting and drying cycles. In contrast to the mudstones, the influence of cyclic wetting and drying on the crushed sand stone, silica sand and glass beads is almost negligible. A higher slaking index, a lower water content before wetting, and lower initial density accelerate the slaking of mudstones.
Journal of Earthquake Engineering
ABSTRACT An earthquake of moment magnitude Mw 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Fi... more ABSTRACT An earthquake of moment magnitude Mw 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Field reconnaissance focused on the geotechnical engineering aspect of the earthquake was carried out in the Kathmandu Valley and regions near the epicenter. This paper presents briefly the geology of Nepal, the accelerogram, and results of standard penetration tests at selected sites in the valley. The study shows the failure case histories including landslides, road embankment settlement, bridge foundations and abutment damage, and liquefaction. The paper also highlights the impact of local soil properties and basin and ridge effect on the severity of damage.
Engineering Structures, 2016
Firstly based on the triaxial rheological curves of greenschist specimen on rock servo-controllin... more Firstly based on the triaxial rheological curves of greenschist specimen on rock servo-controlling rheology equipment, five-component viscoelastic model is put forward to identify the curves that show the viscoelastic rheological properties, which gets the viscoelastic rheological parameters of greenschist. Then a new nonlinear viscous component is put forward. When nonlinear viscous component is parallel connected with the plastic component, a new nonlinear viscoplastic body (NVPB) can be gotten, which may reflect the accelerative rheological properties of rock. At the same time, by connecting NVPB model and five-component viscoelastic model in series, we can construct a new seven-component nonlinear viscoelastoplastic rheological model of rock. Then using complete accelerative rheological curve, proposed seven-component nonlinear viscoelastoplastic rheological model of rock is carried out the identification. The correlative parameters of nonlinear rheological model such as viscoelastic modulus and viscosity etc. are also gained. The comparison between the rheological model and experimental result shows that the nonlinear rheological model is right and reasonable.
Frontiers in Built Environment, 2015
Numerous centrifuge experiments (e.g., Rosebrook 2001; Ugalde et al. 2007; Gajan and Kutter 2008;... more Numerous centrifuge experiments (e.g., Rosebrook 2001; Ugalde et al. 2007; Gajan and Kutter 2008; Deng et al. 2012; Hakhamaneshi et al. 2012; Liu et al. 2013; Allmond and Kutter 2014; Loli et al. 2014) and 1g shake-table experiments (e.g., Shirato et al. 2008; Drosos et al. 2012; Antonellis et al. 2015; Tsatsis and Anastasopoulos 2015) have demonstrated that rocking shallow foundations can be designed to provide re-centering and energy dissipation with little damage to the foundation or superstructure. Each research team listed above studied specific response aspects by varying soil profiles, structural properties and ground motions. As a result of this cumulative body of research, the concept of a controlled share of ductility demand between the superstructure and the foundation as a key ingredient for a rationale and integrated approach to the seismic design of foundations and structures has been gaining acceptance within the research and practicing earthquake engineering communit...
GeoHazards, 2021
Kathmandu Valley lies in an active tectonic zone, meaning that earthquakes are common in the regi... more Kathmandu Valley lies in an active tectonic zone, meaning that earthquakes are common in the region. The most recent was the Gorkha Nepal earthquake, measuring 7.8 Mw. Past earthquakes caused soil liquefaction in the valley with severe damages and destruction of existing critical infrastructures. As for such infrastructures, the road network, health facilities, schools and airports are considered. This paper presents a liquefaction susceptibility map. This map was obtained by computing the liquefaction potential index (LPI) for several boreholes with SPT measurements and clustering the areas with similar values of LPI. Moreover, the locations of existing critical infrastructures were reported on this risk map. Therefore, we noted that 42% of the road network and 16% of the airport area are in zones of very high liquefaction susceptibility, while 60%, 54%, and 64% of health facilities, schools and colleges are in very high liquefaction zones, respectively. This indicates that most of...
An earthquake of moment magnitude (Mw) 7.8 struck Nepal at 06:11 UTC on April 25, 2015. A field r... more An earthquake of moment magnitude (Mw) 7.8 struck Nepal at 06:11 UTC on April 25, 2015. A field reconnaissance was carried out immediately after the main shock. This paper presents the accelerograms and the geology of Nepal. The acceleration response spectra of the motions at the valley show a prominent amplification at the period of 5 sec. This paper describes the effects of local geology and topography on the damage severity during the earthquake. The damage patterns illustrate the strong influence of local geology conditions on the severity of the damage at many places, like soil amplification in Gongabu, Machhapokhari, Ramkot, Purano Naikap, areas along the major rivers in Kathmandu Valley with loose alluvium deposits, and ridge effects on the Swayambhu Nath hill and Chautara. The effect of low frequency amplification caused by the Kathmandu Valley basin is evident from the severe damage to well-designed tall buildings in Kathmandu. Severe damages including ground fissures and l...
Earthquake Spectra
Several experimental studies have shown that rocking shallow foundations have beneficial seismic ... more Several experimental studies have shown that rocking shallow foundations have beneficial seismic performance features: recentering and energy dissipation with little damage. A new publicly available database, “FoRDy” (Foundation Rocking—Dynamic), summarizes the results of dynamic physical model tests of single-degree-of-freedom-like structures supported on rocking foundations. It contains data from five centrifuge and three 1- g shaking table test series that were conducted at experimental facilities in the United States, Greece, and Japan. The database includes 200 model “case histories” that span a wide range of model sizes, soil and structure properties, and seismic excitations. It is compiled as the first step toward building a comprehensive dynamic rocking foundation database, and it has the potential to grow in the future. To illustrate its usefulness, the data are used to show example correlations between the peak drift ratio demand and selected ground motion intensity measur...
Journal of Earthquake Engineering
ABSTRACT This paper reports the structural failures and collapse of heritage structures in Kathma... more ABSTRACT This paper reports the structural failures and collapse of heritage structures in Kathmandu Valley, Nepal, during the 2015 Nepal earthquake, and presents preliminary findings regarding the causes of failures and collapses. Field reconnaissance was carried out immediately after the main shock (Mw 7.8) on April 25 and the strongest aftershock (Mw 7.3) on May 12. It was observed that the performance of heritage structures was influenced by the combination of several factors, including structural and architecture type, configuration and structural deficiency, local site effects and ground-motion characteristics, age and maintenance level, material quality, etc. It was observed that dome structures performed very well, followed by pagoda (tiered temple), and shikhara structures were found as the most vulnerable structures. Moreover, it was observed that structures that had been seismically retrofitted and well maintained appeared to perform well. Some recommendations are made to improve the seismic performance of the heritage structures in Kathmandu Valley.
Canadian Geotechnical Journal
This paper presents a field test program of a large-scale soil-footing-structure system designed ... more This paper presents a field test program of a large-scale soil-footing-structure system designed with a rocking foundation in a cohesive soil, to examine the behaviour of the system and to provide case histories for possible performance-based seismic design of foundations. The rocking system was subjected to slow cyclic loadings at various drift ratios up to 7%. Twenty-four tests were conducted for foundations with varying initial factors of safety against the bearing failure, loading directions, rotation amplitudes, and embedment. A geotechnical investigation was carried out to determine soil properties before and after the experiments. The system performance indices, such as damping, stiffness, settlement and re-centering capability, were quantified and compared to the published literature. Field test results showed that the strength and unit weight of soils at footing edges were increased due to rocking, for the present cohesive soil. The rocking moment capacity increased slightl...
Geomatics, Natural Hazards and Risk
The Gorkha earthquake on April 25, 2015 had significantly affected the livelihood of people and t... more The Gorkha earthquake on April 25, 2015 had significantly affected the livelihood of people and the overall economy in Nepal. The earthquake had caused damage to about half a million private and public buildings, apart from damage to other infrastructures including schools, hospitals, roads, hydropower, irrigation canals, etc. The earthquake had affected the lives of 8 million people. With significant numbers of actors and stakeholders involved in the reconstruction process, no significant relief has reached the ground or is observable even after 3 years of the disaster. The government has formed National Reconstruction Authority (NRA) as the focal authority for the reconstruction process which is leading the reconstruction process with line agencies and other stakeholders. The longitudinal study was carried out through semi-structured interviews with the engineers working under NRA, local people and social mobilizer, group discussions, and field observation from June 2015 to August 2016 focusing on challenges for timely and quality reconstruction. The research also reviews the experiences from past events in similar social and political condition. This study concludes that the situation was the result of larger institutional gaps as the absence of local government, lack of coordination, bureaucratic hurdles and political transition, weak governance and cross-cutting issues as accessibility, manpower shortage, knowledge gap and other socio-cultural aspects. Authors supplement that the good governance and strategic incorporation of social and cultural aspects of reconstructions along with the technical cross-cutting issues like skilled labour, resources availability and construction knowledge could help to expedite the reconstruction process.
Journal of the Institute of Engineering
An earthquake of moment magnitude (Mw ) 7.8 struck the central Nepal at 11:56 am on April 25, 20... more An earthquake of moment magnitude (Mw ) 7.8 struck the central Nepal at 11:56 am on April 25, 2015. More than 9,000 people were killed and thousands of residential buildings, and hundreds other structures were also destroyed. An aftershock of moment magnitude (Mw ) 7.3 hit northeast of Kathmandu on May 12 after 17 days of main shock which caused additional damages. Immediately after the earthquake, authors undertook a field investigation and visited the affected areas. Strong motion records from both earthquakes and their impacts on structures as well as geotechnical issues are presented in this paper. Most of the structures in Nepal are made of adobe, unreinforced masonry, and reinforced concrete. Failure mechanisms of those buildings are briefly explained in this paper. Geotechnical aspects such as soil liquefaction, slope failures, settlement and lateral spreading, and site amplification effects that considerably influenced the damage patterns at many areas are briefly discussed...
Journal of the Institute of Engineering
The Gorkha earthquake on April 25, 2015 has significantly affected the livelihood of people and o... more The Gorkha earthquake on April 25, 2015 has significantly affected the livelihood of people and overall economy in Nepal, causing severe damage and destruction in central Nepal including nation's capital. 800 thousand buildings were affected leaving 8 million people homeless. Challenge of reconstruction of optimum 800 thousand houses is arduous for Nepal Government in background of its turmoil political scenario and weak governance apart from its difficult geographical terrain. Albeit, with significant number of stakeholders involved in the reconstruction process, no appreciable progress has seen to the ground till date, which is reflected over the frustration of affected people. In order to identify factors hindering timely and quality reconstruction, this research has brought basic arguments and ideas prospected by different actors involved in the process. Methodology of the study is comprised with semi structured interviews with social mobilizers, engineers working in the fie...
International Journal of Geotechnical Engineering
Abstract The Gorkha (Nepal) earthquake of the moment magnitude M w 7.8 occurred on 25 April 2015,... more Abstract The Gorkha (Nepal) earthquake of the moment magnitude M w 7.8 occurred on 25 April 2015, with the epicenter 77 km north-west of Kathmandu at a focal depth of 13 km. After the main shock of the earthquake, a field investigation was carried out in the Kathmandu Valley to collect case histories of geotechnical and structural damages. This paper provides the observations of liquefaction case histories and the liquefaction potential assessment based on Standard Penetration Tests for liquefied and non-liquefied sites were performed. Recorded ground motions from the event are presented and the local site effect on the occurrence of liquefaction is described briefly. Observed liquefaction case studies are presented. Ejected soils at liquefied sites were collected and the particle size distributions of ejected soils were analysed. SPT blow counts and the soil profiles at eight liquefied and non-liquefied sites were obtained. The factors of safety against liquefaction with depth and liquefaction potential index of the eight sites were estimated and compared with observed liquefaction areas during Gorkha earthquake. The liquefaction potential indices obtained from the analysis were found to be consistent with the field observation.
Soils and Foundations
Abstract This study investigates the effects of wetting and drying cycles, known as slaking, on t... more Abstract This study investigates the effects of wetting and drying cycles, known as slaking, on the strength-displacement characteristics of crushed mudstone. A series of direct shear tests was conducted by simulating cyclic wetting and drying under different stress conditions using a modified direct shear apparatus. The effects of the stress ratio, the density of specimen, the initial water content before wetting, the slaking index, and the number of wetting and drying cycles on the test results was investigated. Experiments were also performed on less-slakable materials, including crushed sand stone, silica sand and glass beads, to compare the results with the crushed mudstone. Considerable creep displacement on the crushed mudstones was observed during both drying and wetting phases under the constant shear stress conditions. The creep displacement during the drying was more significant than during the wetting phase. The creep displacement accumulated with progressive wetting and drying cycles. The drying-induced displacement was observed when the water content became smaller than the amount of water absorption of the mudstone specimens. Correspondingly, a gradual decrease of the peak stress ratio was observed with the number of wetting and drying cycles. In contrast to the mudstones, the influence of cyclic wetting and drying on the crushed sand stone, silica sand and glass beads is almost negligible. A higher slaking index, a lower water content before wetting, and lower initial density accelerate the slaking of mudstones.
Journal of Earthquake Engineering
ABSTRACT An earthquake of moment magnitude Mw 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Fi... more ABSTRACT An earthquake of moment magnitude Mw 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Field reconnaissance focused on the geotechnical engineering aspect of the earthquake was carried out in the Kathmandu Valley and regions near the epicenter. This paper presents briefly the geology of Nepal, the accelerogram, and results of standard penetration tests at selected sites in the valley. The study shows the failure case histories including landslides, road embankment settlement, bridge foundations and abutment damage, and liquefaction. The paper also highlights the impact of local soil properties and basin and ridge effect on the severity of damage.
Engineering Structures, 2016
Firstly based on the triaxial rheological curves of greenschist specimen on rock servo-controllin... more Firstly based on the triaxial rheological curves of greenschist specimen on rock servo-controlling rheology equipment, five-component viscoelastic model is put forward to identify the curves that show the viscoelastic rheological properties, which gets the viscoelastic rheological parameters of greenschist. Then a new nonlinear viscous component is put forward. When nonlinear viscous component is parallel connected with the plastic component, a new nonlinear viscoplastic body (NVPB) can be gotten, which may reflect the accelerative rheological properties of rock. At the same time, by connecting NVPB model and five-component viscoelastic model in series, we can construct a new seven-component nonlinear viscoelastoplastic rheological model of rock. Then using complete accelerative rheological curve, proposed seven-component nonlinear viscoelastoplastic rheological model of rock is carried out the identification. The correlative parameters of nonlinear rheological model such as viscoelastic modulus and viscosity etc. are also gained. The comparison between the rheological model and experimental result shows that the nonlinear rheological model is right and reasonable.
Frontiers in Built Environment, 2015