Abstract. The paper describes a simple numerical FLAC model that was developed to simulate the dy... more Abstract. The paper describes a simple numerical FLAC model that was developed to simulate the dynamic response of two instrumented reduced-scale model reinforced soil walls constructed on a 1-g shaking table. The models were 1 m high by 1.4 m wide by 2.4 m long and were constructed with a uniform size sand backfill, a polymeric geogrid reinforcement material with appropriately scaled stiffness, and a structural full-height rigid panel facing. The wall toe was constructed to simulate a perfectly hinged toe (i.e. toe allowed to rotate only) in one model and an idealized sliding toe (i.e. toe allowed to rotate and slide horizontally) in the other. Physical and numerical models were subjected to the same stepped amplitude sinusoidal base acceleration record. The material properties of the component materials (e.g. backfill and reinforcement) were determined from independent laboratory testing (reinforcement) and by back-fitting results of a numerical FLAC model for direct shear box tes...
The paper is a synthesis of a recent body of work c a ried out by the writers that is focused on ... more The paper is a synthesis of a recent body of work c a ried out by the writers that is focused on the use of EPS geofoam buffers for seismic load attenua tion gainst rigid soil retaining walls. The paper begins with a description of a series of phys ical 1-m high reduced-scale shaking table tests that were carried out on a physical control w a l and six walls constructed with EPS seismic buffers. These tests provided the first “proof of c n ept” by demonstrating as much as a 40% reduction in peak dynamic loads using vertical EPS buffer layers placed between the rigid wall and the granular backfill soil. Next, details of th e development and verification of a displacement-based model and a FLAC numerical model are described and simulation results verified against the physical shaking table tests. The numerical results include simulations carried out with simple linear elastic constitutive models for the EPS buffers and granular soil backfill and more complex non-linear hysteretic mod ...
The paper describes the development and verification of a FLAC numerical code that was used to si... more The paper describes the development and verification of a FLAC numerical code that was used to simulate the results of an experimental program of reduced-scale geofoam buffer tests. The tests were carried out on 1 m-high rigid wall structures mounted on a large shaking table at the Royal Military College of Canada. The tests showed that vertical inclusions of EPS (expanded polystyrene) geofoam placed against a rigid wall can be used to reduce seismic-induced dynamic earth forces. A numerical FLAC code was developed to simulate a number of physical tests with different stiffness of geofoam buffer materials and the control case with no geofoam inclusion. The paper shows that the numerical model was able to capture the trend in earth forces for different buffer configurations during simulated earthquake loading. In many cases, the quantitative measurements from physical and numerical models are in close agreement. The combined physical test results and numerical results demonstrate tha...
The paper describes an experimental program that was carried out to investigate the potential to ... more The paper describes an experimental program that was carried out to investigate the potential to reduce seismic-induced dynamic earth pressures against rigid wall structures by using a vertical inclusion of expanded polystyrene (EPS) geofoam buffer material. The tests were carried out on 1 m-high by 1.4 m-wide rigid wall structures mounted on a large shaking table at the Royal Military College of Canada. Different geofoam inclusions with a range of modulus values were placed between the rigid wall and a uniformly graded sand material. The entire table payload was subjected to a stepped amplitude base excitation record with peak accelerations as high as 0.9g. The geofoam buffer layer/wall was instrumented to record lateral displacements and total wall forces over the duration of each test. The test results showed clearly that dynamic lateral earth forces were attenuated with decreasing geofoam modulus. For the best case, the total earth force acting against the rigid wall during seis...
Resource developments in glacial environments are becoming increasingly attractive as currently g... more Resource developments in glacial environments are becoming increasingly attractive as currently glacier-covered mineral deposits become exposed, easier to access and more economical to develop. Some mining projects are proposing to excavate large volumes of glacier ice to develop an open pit. Mining into an ice mass is challenging and needs to address the complex interaction of the glacier with pit excavation. Estimations of ice creep movements towards the pit are required to assess operational efforts and mine economics. In this paper the application of the finite difference computer software FLAC in estimating glacier ice deformation rates adjacent to a proposed open pit mine is presented. It is shown that the movement of glacier ice can be adequately modelled with a creep power law constitutive model (Glen's flow law) for ice. However, measured glacier movements are required to properly calibrate the constitutive model parameters. The calibrated model is then used to project glacier movements during ice pit expansion and to assess the stability of the excavated glacier ice face considering different excavation scenarios such as excavation slope angles and stages. The assessment shows that 2D numerical modelling is capable of providing useful insight into potential glacier movement mechanisms and changes in ice deformation rates. It can be a useful tool for planning safe excavation of the glacier ice.
The paper reports the results of six shaking table tests using reduced-scale model walls construc... more The paper reports the results of six shaking table tests using reduced-scale model walls constructed with expanded polystyrene (EPS) panels to reduce dynamic earth loads due to base shaking. The results are compared with a nominal identical rigid (control) wall constructed without a seismic buffer. The test results show that dynamic load attenuation increased with decreasing geofoam stiffness. The test with the highest buffer stiffness resulted in a 15% reduction in dynamic load and the test with lowest stiffness resulted in a 40% reduction in dynamic load compared with the control wall. The results of these experiments provide proof of the concept that EPS panels placed against rigid walls can act as seismic buffers to attenuate dynamic loads due to ground shaking (e.g. earthquake). Additional quantitative data related to load–deformation–time response, back-calculated elastic modulus values for the EPS seismic buffer configurations, dynamic interface shear properties, acceleration...
Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads... more Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerogra...
Abstract. The paper describes a simple numerical FLAC model that was developed to simulate the dy... more Abstract. The paper describes a simple numerical FLAC model that was developed to simulate the dynamic response of two instrumented reduced-scale model reinforced soil walls constructed on a 1-g shaking table. The models were 1 m high by 1.4 m wide by 2.4 m long and were constructed with a uniform size sand backfill, a polymeric geogrid reinforcement material with appropriately scaled stiffness, and a structural full-height rigid panel facing. The wall toe was constructed to simulate a perfectly hinged toe (i.e. toe allowed to rotate only) in one model and an idealized sliding toe (i.e. toe allowed to rotate and slide horizontally) in the other. Physical and numerical models were subjected to the same stepped amplitude sinusoidal base acceleration record. The material properties of the component materials (e.g. backfill and reinforcement) were determined from independent laboratory testing (reinforcement) and by back-fitting results of a numerical FLAC model for direct shear box tes...
The paper is a synthesis of a recent body of work c a ried out by the writers that is focused on ... more The paper is a synthesis of a recent body of work c a ried out by the writers that is focused on the use of EPS geofoam buffers for seismic load attenua tion gainst rigid soil retaining walls. The paper begins with a description of a series of phys ical 1-m high reduced-scale shaking table tests that were carried out on a physical control w a l and six walls constructed with EPS seismic buffers. These tests provided the first “proof of c n ept” by demonstrating as much as a 40% reduction in peak dynamic loads using vertical EPS buffer layers placed between the rigid wall and the granular backfill soil. Next, details of th e development and verification of a displacement-based model and a FLAC numerical model are described and simulation results verified against the physical shaking table tests. The numerical results include simulations carried out with simple linear elastic constitutive models for the EPS buffers and granular soil backfill and more complex non-linear hysteretic mod ...
The paper describes the development and verification of a FLAC numerical code that was used to si... more The paper describes the development and verification of a FLAC numerical code that was used to simulate the results of an experimental program of reduced-scale geofoam buffer tests. The tests were carried out on 1 m-high rigid wall structures mounted on a large shaking table at the Royal Military College of Canada. The tests showed that vertical inclusions of EPS (expanded polystyrene) geofoam placed against a rigid wall can be used to reduce seismic-induced dynamic earth forces. A numerical FLAC code was developed to simulate a number of physical tests with different stiffness of geofoam buffer materials and the control case with no geofoam inclusion. The paper shows that the numerical model was able to capture the trend in earth forces for different buffer configurations during simulated earthquake loading. In many cases, the quantitative measurements from physical and numerical models are in close agreement. The combined physical test results and numerical results demonstrate tha...
The paper describes an experimental program that was carried out to investigate the potential to ... more The paper describes an experimental program that was carried out to investigate the potential to reduce seismic-induced dynamic earth pressures against rigid wall structures by using a vertical inclusion of expanded polystyrene (EPS) geofoam buffer material. The tests were carried out on 1 m-high by 1.4 m-wide rigid wall structures mounted on a large shaking table at the Royal Military College of Canada. Different geofoam inclusions with a range of modulus values were placed between the rigid wall and a uniformly graded sand material. The entire table payload was subjected to a stepped amplitude base excitation record with peak accelerations as high as 0.9g. The geofoam buffer layer/wall was instrumented to record lateral displacements and total wall forces over the duration of each test. The test results showed clearly that dynamic lateral earth forces were attenuated with decreasing geofoam modulus. For the best case, the total earth force acting against the rigid wall during seis...
Resource developments in glacial environments are becoming increasingly attractive as currently g... more Resource developments in glacial environments are becoming increasingly attractive as currently glacier-covered mineral deposits become exposed, easier to access and more economical to develop. Some mining projects are proposing to excavate large volumes of glacier ice to develop an open pit. Mining into an ice mass is challenging and needs to address the complex interaction of the glacier with pit excavation. Estimations of ice creep movements towards the pit are required to assess operational efforts and mine economics. In this paper the application of the finite difference computer software FLAC in estimating glacier ice deformation rates adjacent to a proposed open pit mine is presented. It is shown that the movement of glacier ice can be adequately modelled with a creep power law constitutive model (Glen's flow law) for ice. However, measured glacier movements are required to properly calibrate the constitutive model parameters. The calibrated model is then used to project glacier movements during ice pit expansion and to assess the stability of the excavated glacier ice face considering different excavation scenarios such as excavation slope angles and stages. The assessment shows that 2D numerical modelling is capable of providing useful insight into potential glacier movement mechanisms and changes in ice deformation rates. It can be a useful tool for planning safe excavation of the glacier ice.
The paper reports the results of six shaking table tests using reduced-scale model walls construc... more The paper reports the results of six shaking table tests using reduced-scale model walls constructed with expanded polystyrene (EPS) panels to reduce dynamic earth loads due to base shaking. The results are compared with a nominal identical rigid (control) wall constructed without a seismic buffer. The test results show that dynamic load attenuation increased with decreasing geofoam stiffness. The test with the highest buffer stiffness resulted in a 15% reduction in dynamic load and the test with lowest stiffness resulted in a 40% reduction in dynamic load compared with the control wall. The results of these experiments provide proof of the concept that EPS panels placed against rigid walls can act as seismic buffers to attenuate dynamic loads due to ground shaking (e.g. earthquake). Additional quantitative data related to load–deformation–time response, back-calculated elastic modulus values for the EPS seismic buffer configurations, dynamic interface shear properties, acceleration...
Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads... more Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerogra...
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