Several corrections have been proposed since 1990s for the interpretation of liquefaction potenti... more Several corrections have been proposed since 1990s for the interpretation of liquefaction potential and anal-ysis of the consequences of liquefaction based on cone penetration test (CPT) measurements. However, few publications address how these factors affect the calculation results. In this study, extensive studies of soil liquefaction and its consequences were performed using selected CPT data from two sites located within 7 km of the fault rupture of the 1999 Kocaeli, Turkey earthquake (Mw = 7.5). The effects of thickness of inter-val for averaging, thin layer correction and transition zone were examined in detail.
In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding... more In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding wall is generally taken as the product of seismic coefficient (݇ ு) and the soil mass behind the wall, ∆ܲ ா = ݇ ு • ܪߛ ଶ , as developed by Wood (1973) and modified by Whitman (1991). Wood's study and most of the research thenceforth were based on the assumption that the wall and the retained soil are connected to a rigid base. This assumption neglects the fact that comparing to the mass mobilized by an earthquake, the size of the wall and its retained soil are relatively small. In other words, even though the wall is connected to a relatively rigid base, the base exhibits certain movement during an earthquake. In addition, there is much disagreement in current practice related to the value of ݇ ு used with respect to the relationship to peak ground acceleration (PGA). In this study, a series of elasto-plastic pseudostatic finite element analyses were performed to assess the appropriateness of the Wood (1973) equation for determining the seismically induced lateral earth pressures on the stem of the restrained wall, and relationships were established between ݇ ு and PGA based on the momentum conservation law. The results indicate that the increment of seismic earth pressure acting on non-yielding wall is a function of ݇ ு and the supporting condition. They also indicate that a value of ݇ ு of 25% of PGA seems reasonable and somewhat conservative for the design of normal structures. RÉSUMÉ: L'augmentation de pression terrestre induite de façon sismique sur un mur rigide non-cédant est généralement calculée comme le produit du coefficient sismique (݇ ு) et de la masse de sol retenu derrière le mur, ∆ܲ ா = ݇ ு • ܪߛ ଶ , comme développé par Wood (1973) et modifié par Whitman (1991). L'étude de Wood et la plupart de ses recherches ont été basées sur l'hypothèse que le mur et le sol retenu sont connectés a une base rigide. Cette hypothèse néglige le fait qu'en comparaison de la masse mobilisée par un tremblement de terre, la taille du mur et du sol qu'il retient sont relativement petites. En d'autres mots, même si le mur reste connecté à une base relativement rigide, la base subit certains déplacements durant un tremblement de terre. Confusions et conflits existent sur la valeur de ݇ ு par rapport à l'accélération maximale du sol (PGA). Dans cette étude, une série d'analyses d'éléments finis élastoplastiques pseudostatiques a été réalisée pour évaluer la convenance de l'équation de Wood (1973) pour déterminer les pressions sismiques latérales induites sur le pied du mur de soutien et la relation entre ݇ ு et PGA a été examinée en se basant sur la loi de conservation des moments. Les résultats indiquent que l'augmentation de pression terrestre sismique agissant sur le mur non-cédant est une fonction de ݇ ு de la condition de support. Il est également établi qu'une valeur de ݇ ு de 25% du PGA semble raisonnable et également conservative pour la conception de structures normales.
Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loo... more Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loose sandy deposits exist and groundwater is relatively deep. Other than research performed for liquefaction-induced settlement, studies on seismic settlement of dry sand are limited although Silver and Seed (1971) began to pioneer the work in the early 1970's. Moreover, most of the existing methods for estimating seismic settlement in dry sands are based on the standard penetration test. This paper presents a new method for evaluating seismic settlement in dry sand based on shear wave velocity. A detailed procedure, including the calculations of cyclic shear strain and volumetric strain, is discussed. Special attention is paid to the discussion of the relationship between relative density and shear wave velocity and the limiting volumetric strain. A case study is provided to illustrate the application of the procedure.
The seismic settlement of dry sands becomes one of the major geological hazards in areas where lo... more The seismic settlement of dry sands becomes one of the major geological hazards in areas where loose sandy deposits exist, and groundwater is relatively deep as human activities and urban develop ment moving towards these areas. Research related to the evaluation of seismic settlement of dry sand seems paused for a period since pioneer work of Silver and Seed (1971) in the early 1970's. Later research related to the topic was found by Tokimatsu and Seed (1987) and Pradel (1998). Both papers were based on the use of Standard Penetration Test (SPT). Yi (2010) was the first attempting to evaluate the seismic settlement of dry sand using Cone Penetration Test (CPT) data. In this paper, the procedures to evaluate seismic settlement in dry sand based on CPT data was summarized and the relationship between volumetric strain and cyclic shear strain was updated for CPT data by considering various effects such as fine contents and overburden pressure based on the most recent research findings.
In most of the early studies, researchers correlated shear wave velocity with Standard Penetratio... more In most of the early studies, researchers correlated shear wave velocity with Standard Penetration Test blowcounts (e.g., Kanai 1966 and Ohta & Goto 1976). Later correlations developed by various researchers (e.g., Ohta & Goto 1978; Andrus et al. 2004, Branderburg et al., 2010; and Wair et al., 2012) directly or indirectly took into account the effect of overburden pressure. The author of this paper found that the fines contents and the mean grain size of the soil also play an important role in the estimation of shear wave velocity based on SPT data. In this paper, a predictive equation for estimating shear wave velocity based on SPT profile data including SPT blowcounts (N60), fines contents (FC) and normalized mean effective confining stress (σ_m^'/P_a) are presented. The equation was developed based on a statistical analysis of 179 valid data sets obtained from northern to southern California with soil profiles predominately of clean sands, silty sands or sandy silts. The comparison of measured and calculated shear wave velocities yields a better prediction using the proposed equation than existing methods for soils which vary from clean sand to sandy silt with low plasticity.
Evaluation of liquefaction-induced lateral spreading is very important for the design of structur... more Evaluation of liquefaction-induced lateral spreading is very important for the design of structures located on gently sloping ground and with relatively shallow groundwater. Extensive research has been performed on the calculation of liquefaction-induced lateral spreading based on the standard penetration test (SPT) and cone penetration test (CPT) data by various researchers
Interpretations of geotechnical parameters based on Cone Penetration Test (CPT) data were perform... more Interpretations of geotechnical parameters based on Cone Penetration Test (CPT) data were performed and compared with Standard Penetration Test (SPT) data and laboratory testing results collected from various sites in California. Specific attention was paid to the estimation of fines content and conversion of CPT data to SPT 60 1 blowcounts since they are often needed in seismic settlement evaluation of dry sand for the use of Pradel's (1998) method. A new relationship between volumetric strain, cyclic shear strain, and normalized tip resistance was derived based on the laboratory test data of Silver and Seed (1971) for dry clean sands. An example of the proposed CPT-based method is presented with a comparison to the results calculated using Pradel's original method as well as with the results based on SPT data from adjacent borings.
For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model i... more For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model is presented consisting of a modified equation for an initial loading curve and a modified equation for constructing the hysteresis loop. The performance of the model was evaluated by simulating the frequently utilized relationships of shear modulus versus shear strain and damping ratio versus shear strain of various types of soils accumulated over the past decades. The outcomes indicated that the new model presented describes the measured relationships with excellent correlations. The new model can simulate not only the work-hardening, but also work-softening behaviors of soils.
Several corrections have been proposed since 1990s for the interpretation of liquefaction potenti... more Several corrections have been proposed since 1990s for the interpretation of liquefaction potential and anal-ysis of the consequences of liquefaction based on cone penetration test (CPT) measurements. However, few publications address how these factors affect the calculation results. In this study, extensive studies of soil liquefaction and its consequences were performed using selected CPT data from two sites located within 7 km of the fault rupture of the 1999 Kocaeli, Turkey earthquake (Mw = 7.5). The effects of thickness of inter-val for averaging, thin layer correction and transition zone were examined in detail.
In most of the early studies, researchers correlated shear wave velocity with Standard Penetratio... more In most of the early studies, researchers correlated shear wave velocity with Standard Penetration Test blowcounts (e.g., Kanai 1966 and Ohta & Goto 1976). Later correlations developed by various researchers (e.g., Ohta & Goto 1978; Andrus et al. 2004, Branderburg et al., 2010; and Wair et al., 2012) directly or indirectly took into account the effect of overburden pressure. The author of this paper found that the fines contents and the mean grain size of the soil also play an important role in the estimation of shear wave velocity based on SPT data. In this paper, a predictive equation for estimating shear wave velocity based on SPT profile data including SPT blowcounts (N60), fines contents (FC) and normalized mean effective confining stress (σ_m^'/P_a) are presented. The equation was developed based on a statistical analysis of 179 valid data sets obtained from northern to southern California with soil profiles predominately of clean sands, silty sands or sandy silts. The comparison of measured and calculated shear wave velocities yields a better prediction using the proposed equation than existing methods for soils which vary from clean sand to sandy silt with low plasticity.
Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loo... more Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loose sandy deposits exist and groundwater is relatively deep. Other than research performed for liquefaction-induced settlement, studies on seismic settlement of dry sand are limited although Silver and Seed (1971) began to pioneer the work in the early 1970’s. Moreover, most of the existing methods for estimating seismic settlement in dry sands are based on the standard penetration test. This paper presents a new method for evaluating seismic settlement in dry sand based on shear wave velocity. A detailed procedure, including the calculations of cyclic shear strain and volumetric strain, is discussed. Special attention is paid to the discussion of the relationship between relative density and shear wave velocity and the limiting volumetric strain. A case study is provided to illustrate the application of the procedure. Introduction As the world’s population increases, human activities and...
Evaluation of liquefaction-induced lateral spreading is very important for the design of structur... more Evaluation of liquefaction-induced lateral spreading is very important for the design of structures located on gently sloping ground and with relatively shallow groundwater. Extensive research has been performed on the calculation of liquefaction-induced lateral spreading based on the standard penetration test (SPT) and cone penetration test (CPT) data by various researchers (Bartlett and Youd 1992, 1995, Rauch, 1997; Zhang et al., 2004; Idriss and Boulanger, 2008). However, few published papers can be found that address the calculation of liquefaction-induced lateral spreading based on shear wave velocity. This paper presents a procedure to evaluate liquefaction-induced lateral spreading directly based on shear wave velocity. New empirical relationships for factor of safety against liquefaction, maximum shear strain, and shear wave velocity are developed based on the laboratory tests performed at the University of Tokyo (Ishihara and Yoshimine 1992, Yoshimine et al. 2006). The resu...
In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding... more In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding wall is generally taken as the product of seismic coefficient () and the soil mass behind the wall, ∆ = • 2 , as developed by Wood (1973) and modified by Whitman (1991). Wood's study and most of the research thenceforth were based on the assumption that the wall and the retained soil are connected to a rigid base. This assumption neglects the fact that comparing to the mass mobilized by an earthquake, the size of the wall and its retained soil are relatively small. In other words, even though the wall is connected to a relatively rigid base, the base exhibits certain movement during an earthquake. In addition, there is much disagreement in current practice related to the value of used with respect to the relationship to peak ground acceleration (PGA). In this study, a series of elasto-plastic pseudostatic finite element analyses were performed to assess the appropriateness of the Wood (1973) equation for determining the seismically induced lateral earth pressures on the stem of the restrained wall, and relationships were established between and PGA based on the momentum conservation law. The results indicate that the increment of seismic earth pressure acting on non-yielding wall is a function of and the supporting condition. They also indicate that a value of of 25% of PGA seems reasonable and somewhat conservative for the design of normal structures. RÉSUMÉ: L'augmentation de pression terrestre induite de façon sismique sur un mur rigide non-cédant est généralement calculée comme le produit du coefficient sismique () et de la masse de sol retenu derrière le mur, ∆ = • 2 , comme développé par Wood (1973) et modifié par Whitman (1991). L'étude de Wood et la plupart de ses recherches ont été basées sur l'hypothèse que le mur et le sol retenu sont connectés a une base rigide. Cette hypothèse néglige le fait qu'en comparaison de la masse mobilisée par un tremblement de terre, la taille du mur et du sol qu'il retient sont relativement petites. En d'autres mots, même si le mur reste connecté à une base relativement rigide, la base subit certains déplacements durant un tremblement de terre. Confusions et conflits existent sur la valeur de par rapport à l'accélération maximale du sol (PGA). Dans cette étude, une série d'analyses d'éléments finis élastoplastiques pseudostatiques a été réalisée pour évaluer la convenance de l'équation de Wood (1973) pour déterminer les pressions sismiques latérales induites sur le pied du mur de soutien et la relation entre et PGA a été examinée en se basant sur la loi de conservation des moments. Les résultats indiquent que l'augmentation de pression terrestre sismique agissant sur le mur non-cédant est une fonction de de la condition de support. Il est également établi qu'une valeur de de 25% du PGA semble raisonnable et également conservative pour la conception de structures normales.
9th US National & 10th Canadian Conf. on EQ Engg. , 2010
Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loo... more Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loose sandy deposits exist and groundwater is relatively deep. Other than research performed for liquefaction-induced settlement, studies on seismic settlement of dry sand are limited although Silver and Seed (1971) began to pioneer the work in the early 1970's. Moreover, most of the existing methods for estimating seismic settlement in dry sands are based on the standard penetration test. This paper presents a new method for evaluating seismic settlement in dry sand based on shear wave velocity. A detailed procedure, including the calculations of cyclic shear strain and volumetric strain, is discussed. Special attention is paid to the discussion of the relationship between relative density and shear wave velocity and the limiting volumetric strain. A case study is provided to illustrate the application of the procedure.
For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model i... more For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model is presented consisting of a modified equation for an initial loading curve and a modified equation for constructing the hysteresis loop. The performance of the model was evaluated by simulating the frequently utilized relationships of shear modulus versus shear strain and damping ratio versus shear strain of various types of soils accumulated over the past decades. The outcomes indicated that the new model presented describes the measured relationships with excellent correlations. The new model can simulate not only the work-hardening, but also work-softening behaviors of soils.
Several corrections have been proposed since 1990s for the interpretation of liquefaction potenti... more Several corrections have been proposed since 1990s for the interpretation of liquefaction potential and anal-ysis of the consequences of liquefaction based on cone penetration test (CPT) measurements. However, few publications address how these factors affect the calculation results. In this study, extensive studies of soil liquefaction and its consequences were performed using selected CPT data from two sites located within 7 km of the fault rupture of the 1999 Kocaeli, Turkey earthquake (Mw = 7.5). The effects of thickness of inter-val for averaging, thin layer correction and transition zone were examined in detail.
In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding... more In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding wall is generally taken as the product of seismic coefficient (݇ ு) and the soil mass behind the wall, ∆ܲ ா = ݇ ு • ܪߛ ଶ , as developed by Wood (1973) and modified by Whitman (1991). Wood's study and most of the research thenceforth were based on the assumption that the wall and the retained soil are connected to a rigid base. This assumption neglects the fact that comparing to the mass mobilized by an earthquake, the size of the wall and its retained soil are relatively small. In other words, even though the wall is connected to a relatively rigid base, the base exhibits certain movement during an earthquake. In addition, there is much disagreement in current practice related to the value of ݇ ு used with respect to the relationship to peak ground acceleration (PGA). In this study, a series of elasto-plastic pseudostatic finite element analyses were performed to assess the appropriateness of the Wood (1973) equation for determining the seismically induced lateral earth pressures on the stem of the restrained wall, and relationships were established between ݇ ு and PGA based on the momentum conservation law. The results indicate that the increment of seismic earth pressure acting on non-yielding wall is a function of ݇ ு and the supporting condition. They also indicate that a value of ݇ ு of 25% of PGA seems reasonable and somewhat conservative for the design of normal structures. RÉSUMÉ: L'augmentation de pression terrestre induite de façon sismique sur un mur rigide non-cédant est généralement calculée comme le produit du coefficient sismique (݇ ு) et de la masse de sol retenu derrière le mur, ∆ܲ ா = ݇ ு • ܪߛ ଶ , comme développé par Wood (1973) et modifié par Whitman (1991). L'étude de Wood et la plupart de ses recherches ont été basées sur l'hypothèse que le mur et le sol retenu sont connectés a une base rigide. Cette hypothèse néglige le fait qu'en comparaison de la masse mobilisée par un tremblement de terre, la taille du mur et du sol qu'il retient sont relativement petites. En d'autres mots, même si le mur reste connecté à une base relativement rigide, la base subit certains déplacements durant un tremblement de terre. Confusions et conflits existent sur la valeur de ݇ ு par rapport à l'accélération maximale du sol (PGA). Dans cette étude, une série d'analyses d'éléments finis élastoplastiques pseudostatiques a été réalisée pour évaluer la convenance de l'équation de Wood (1973) pour déterminer les pressions sismiques latérales induites sur le pied du mur de soutien et la relation entre ݇ ு et PGA a été examinée en se basant sur la loi de conservation des moments. Les résultats indiquent que l'augmentation de pression terrestre sismique agissant sur le mur non-cédant est une fonction de ݇ ு de la condition de support. Il est également établi qu'une valeur de ݇ ு de 25% du PGA semble raisonnable et également conservative pour la conception de structures normales.
Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loo... more Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loose sandy deposits exist and groundwater is relatively deep. Other than research performed for liquefaction-induced settlement, studies on seismic settlement of dry sand are limited although Silver and Seed (1971) began to pioneer the work in the early 1970's. Moreover, most of the existing methods for estimating seismic settlement in dry sands are based on the standard penetration test. This paper presents a new method for evaluating seismic settlement in dry sand based on shear wave velocity. A detailed procedure, including the calculations of cyclic shear strain and volumetric strain, is discussed. Special attention is paid to the discussion of the relationship between relative density and shear wave velocity and the limiting volumetric strain. A case study is provided to illustrate the application of the procedure.
The seismic settlement of dry sands becomes one of the major geological hazards in areas where lo... more The seismic settlement of dry sands becomes one of the major geological hazards in areas where loose sandy deposits exist, and groundwater is relatively deep as human activities and urban develop ment moving towards these areas. Research related to the evaluation of seismic settlement of dry sand seems paused for a period since pioneer work of Silver and Seed (1971) in the early 1970's. Later research related to the topic was found by Tokimatsu and Seed (1987) and Pradel (1998). Both papers were based on the use of Standard Penetration Test (SPT). Yi (2010) was the first attempting to evaluate the seismic settlement of dry sand using Cone Penetration Test (CPT) data. In this paper, the procedures to evaluate seismic settlement in dry sand based on CPT data was summarized and the relationship between volumetric strain and cyclic shear strain was updated for CPT data by considering various effects such as fine contents and overburden pressure based on the most recent research findings.
In most of the early studies, researchers correlated shear wave velocity with Standard Penetratio... more In most of the early studies, researchers correlated shear wave velocity with Standard Penetration Test blowcounts (e.g., Kanai 1966 and Ohta & Goto 1976). Later correlations developed by various researchers (e.g., Ohta & Goto 1978; Andrus et al. 2004, Branderburg et al., 2010; and Wair et al., 2012) directly or indirectly took into account the effect of overburden pressure. The author of this paper found that the fines contents and the mean grain size of the soil also play an important role in the estimation of shear wave velocity based on SPT data. In this paper, a predictive equation for estimating shear wave velocity based on SPT profile data including SPT blowcounts (N60), fines contents (FC) and normalized mean effective confining stress (σ_m^'/P_a) are presented. The equation was developed based on a statistical analysis of 179 valid data sets obtained from northern to southern California with soil profiles predominately of clean sands, silty sands or sandy silts. The comparison of measured and calculated shear wave velocities yields a better prediction using the proposed equation than existing methods for soils which vary from clean sand to sandy silt with low plasticity.
Evaluation of liquefaction-induced lateral spreading is very important for the design of structur... more Evaluation of liquefaction-induced lateral spreading is very important for the design of structures located on gently sloping ground and with relatively shallow groundwater. Extensive research has been performed on the calculation of liquefaction-induced lateral spreading based on the standard penetration test (SPT) and cone penetration test (CPT) data by various researchers
Interpretations of geotechnical parameters based on Cone Penetration Test (CPT) data were perform... more Interpretations of geotechnical parameters based on Cone Penetration Test (CPT) data were performed and compared with Standard Penetration Test (SPT) data and laboratory testing results collected from various sites in California. Specific attention was paid to the estimation of fines content and conversion of CPT data to SPT 60 1 blowcounts since they are often needed in seismic settlement evaluation of dry sand for the use of Pradel's (1998) method. A new relationship between volumetric strain, cyclic shear strain, and normalized tip resistance was derived based on the laboratory test data of Silver and Seed (1971) for dry clean sands. An example of the proposed CPT-based method is presented with a comparison to the results calculated using Pradel's original method as well as with the results based on SPT data from adjacent borings.
For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model i... more For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model is presented consisting of a modified equation for an initial loading curve and a modified equation for constructing the hysteresis loop. The performance of the model was evaluated by simulating the frequently utilized relationships of shear modulus versus shear strain and damping ratio versus shear strain of various types of soils accumulated over the past decades. The outcomes indicated that the new model presented describes the measured relationships with excellent correlations. The new model can simulate not only the work-hardening, but also work-softening behaviors of soils.
Several corrections have been proposed since 1990s for the interpretation of liquefaction potenti... more Several corrections have been proposed since 1990s for the interpretation of liquefaction potential and anal-ysis of the consequences of liquefaction based on cone penetration test (CPT) measurements. However, few publications address how these factors affect the calculation results. In this study, extensive studies of soil liquefaction and its consequences were performed using selected CPT data from two sites located within 7 km of the fault rupture of the 1999 Kocaeli, Turkey earthquake (Mw = 7.5). The effects of thickness of inter-val for averaging, thin layer correction and transition zone were examined in detail.
In most of the early studies, researchers correlated shear wave velocity with Standard Penetratio... more In most of the early studies, researchers correlated shear wave velocity with Standard Penetration Test blowcounts (e.g., Kanai 1966 and Ohta & Goto 1976). Later correlations developed by various researchers (e.g., Ohta & Goto 1978; Andrus et al. 2004, Branderburg et al., 2010; and Wair et al., 2012) directly or indirectly took into account the effect of overburden pressure. The author of this paper found that the fines contents and the mean grain size of the soil also play an important role in the estimation of shear wave velocity based on SPT data. In this paper, a predictive equation for estimating shear wave velocity based on SPT profile data including SPT blowcounts (N60), fines contents (FC) and normalized mean effective confining stress (σ_m^'/P_a) are presented. The equation was developed based on a statistical analysis of 179 valid data sets obtained from northern to southern California with soil profiles predominately of clean sands, silty sands or sandy silts. The comparison of measured and calculated shear wave velocities yields a better prediction using the proposed equation than existing methods for soils which vary from clean sand to sandy silt with low plasticity.
Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loo... more Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loose sandy deposits exist and groundwater is relatively deep. Other than research performed for liquefaction-induced settlement, studies on seismic settlement of dry sand are limited although Silver and Seed (1971) began to pioneer the work in the early 1970’s. Moreover, most of the existing methods for estimating seismic settlement in dry sands are based on the standard penetration test. This paper presents a new method for evaluating seismic settlement in dry sand based on shear wave velocity. A detailed procedure, including the calculations of cyclic shear strain and volumetric strain, is discussed. Special attention is paid to the discussion of the relationship between relative density and shear wave velocity and the limiting volumetric strain. A case study is provided to illustrate the application of the procedure. Introduction As the world’s population increases, human activities and...
Evaluation of liquefaction-induced lateral spreading is very important for the design of structur... more Evaluation of liquefaction-induced lateral spreading is very important for the design of structures located on gently sloping ground and with relatively shallow groundwater. Extensive research has been performed on the calculation of liquefaction-induced lateral spreading based on the standard penetration test (SPT) and cone penetration test (CPT) data by various researchers (Bartlett and Youd 1992, 1995, Rauch, 1997; Zhang et al., 2004; Idriss and Boulanger, 2008). However, few published papers can be found that address the calculation of liquefaction-induced lateral spreading based on shear wave velocity. This paper presents a procedure to evaluate liquefaction-induced lateral spreading directly based on shear wave velocity. New empirical relationships for factor of safety against liquefaction, maximum shear strain, and shear wave velocity are developed based on the laboratory tests performed at the University of Tokyo (Ishihara and Yoshimine 1992, Yoshimine et al. 2006). The resu...
In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding... more In current practice, the increment of seismically induced earth pressure on a rigid, non-yielding wall is generally taken as the product of seismic coefficient () and the soil mass behind the wall, ∆ = • 2 , as developed by Wood (1973) and modified by Whitman (1991). Wood's study and most of the research thenceforth were based on the assumption that the wall and the retained soil are connected to a rigid base. This assumption neglects the fact that comparing to the mass mobilized by an earthquake, the size of the wall and its retained soil are relatively small. In other words, even though the wall is connected to a relatively rigid base, the base exhibits certain movement during an earthquake. In addition, there is much disagreement in current practice related to the value of used with respect to the relationship to peak ground acceleration (PGA). In this study, a series of elasto-plastic pseudostatic finite element analyses were performed to assess the appropriateness of the Wood (1973) equation for determining the seismically induced lateral earth pressures on the stem of the restrained wall, and relationships were established between and PGA based on the momentum conservation law. The results indicate that the increment of seismic earth pressure acting on non-yielding wall is a function of and the supporting condition. They also indicate that a value of of 25% of PGA seems reasonable and somewhat conservative for the design of normal structures. RÉSUMÉ: L'augmentation de pression terrestre induite de façon sismique sur un mur rigide non-cédant est généralement calculée comme le produit du coefficient sismique () et de la masse de sol retenu derrière le mur, ∆ = • 2 , comme développé par Wood (1973) et modifié par Whitman (1991). L'étude de Wood et la plupart de ses recherches ont été basées sur l'hypothèse que le mur et le sol retenu sont connectés a une base rigide. Cette hypothèse néglige le fait qu'en comparaison de la masse mobilisée par un tremblement de terre, la taille du mur et du sol qu'il retient sont relativement petites. En d'autres mots, même si le mur reste connecté à une base relativement rigide, la base subit certains déplacements durant un tremblement de terre. Confusions et conflits existent sur la valeur de par rapport à l'accélération maximale du sol (PGA). Dans cette étude, une série d'analyses d'éléments finis élastoplastiques pseudostatiques a été réalisée pour évaluer la convenance de l'équation de Wood (1973) pour déterminer les pressions sismiques latérales induites sur le pied du mur de soutien et la relation entre et PGA a été examinée en se basant sur la loi de conservation des moments. Les résultats indiquent que l'augmentation de pression terrestre sismique agissant sur le mur non-cédant est une fonction de de la condition de support. Il est également établi qu'une valeur de de 25% du PGA semble raisonnable et également conservative pour la conception de structures normales.
9th US National & 10th Canadian Conf. on EQ Engg. , 2010
Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loo... more Seismic settlement in dry sands is a major hazard especially in inland and desert areas where loose sandy deposits exist and groundwater is relatively deep. Other than research performed for liquefaction-induced settlement, studies on seismic settlement of dry sand are limited although Silver and Seed (1971) began to pioneer the work in the early 1970's. Moreover, most of the existing methods for estimating seismic settlement in dry sands are based on the standard penetration test. This paper presents a new method for evaluating seismic settlement in dry sand based on shear wave velocity. A detailed procedure, including the calculations of cyclic shear strain and volumetric strain, is discussed. Special attention is paid to the discussion of the relationship between relative density and shear wave velocity and the limiting volumetric strain. A case study is provided to illustrate the application of the procedure.
For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model i... more For this paper, research on nonlinear cyclic characteristics of soils was reviewed. A new model is presented consisting of a modified equation for an initial loading curve and a modified equation for constructing the hysteresis loop. The performance of the model was evaluated by simulating the frequently utilized relationships of shear modulus versus shear strain and damping ratio versus shear strain of various types of soils accumulated over the past decades. The outcomes indicated that the new model presented describes the measured relationships with excellent correlations. The new model can simulate not only the work-hardening, but also work-softening behaviors of soils.
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