Rodrigo Salgado | Purdue University (original) (raw)
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Papers by Rodrigo Salgado
Drilled displacement piles are being increasingly used as foundation elements, particularly in pr... more Drilled displacement piles are being increasingly used as foundation elements, particularly in projects requiring fast construction. Different types of drilled displacement (DD) piles are available in practice. DD piles are classified according to the drilling tool design and installation method. The capacity of a DD pile, depending on its type, is between the capacities of geometrically similar nondisplacement and full-displacement piles installed in the same soil profile. This paper provides an overview of the different types of DD piles and their installation techniques and describes three design methods used in practice. It also compares DD pile capacities obtained with these design methods for two different sites.
Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Adminis... more Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration.
… on Case Histories …, Jan 1, 2008
When piles are installed by jacking or driving, they cause substantial changes in the state of so... more When piles are installed by jacking or driving, they cause substantial changes in the state of soil located near the pile. These changes result from the complex loading imposed on the soil by expansion of a cylindrical cavity to make room for the pile, by multiple cycles of shearing in the vertical direction as the pile gradually moves down into
Geotechnical design has traditionally been done using working stress design (WSD). Working stress... more Geotechnical design has traditionally been done using working stress design (WSD). Working stress design identifies limit states for a structure, then protects against their occurrence using factors of safety. Load and resistance factor design (LRFD) uses load and resistance factors instead of factors of safety. LRFD also establishes the geotechnical resistance much more precisely than WSD. This research establishes load
Advances in Deep Foundations, 2005
... his Terzaghi Lecture (O'Neill 2001) on pile shaft resistance and the FHWA manual publishe... more ... his Terzaghi Lecture (O'Neill 2001) on pile shaft resistance and the FHWA manual published with Lymon C. Reese (Reese and O'Neil ... FEM analysis using the commercial software ABAQUS was performed to obtain the base resistances of drilled shafts in sandy soils (Lee and ...
Computers and Geotechnics, 2005
Footings are often used to support structures at sites where the soils near the surface are suffi... more Footings are often used to support structures at sites where the soils near the surface are sufficiently strong to serve as a bearing layer. In this study, estimation of the bearing capacity of footings resting on a soil mass acted upon by a surcharge is investigated and related to the cone resistance qc. Non-linear finite element analyses based on a
Journal of Geotechnical and Geoenvironmental Engineering, 2003
... The behavior of open-ended piles is more complex, with a response generally intermediate betw... more ... The behavior of open-ended piles is more complex, with a response generally intermediate between those of nondisplacement and displacement piles. ... The tip displacement of drilled shafts in sands. Proc ... The effect of pile type on design parameters for driven piles. Proc., 7th ...
Journal of Geotechnical and Geoenvironmental Engineering, 2005
In the present paper, the estimation of limit unit bearing capacity of axially loaded circular fo... more In the present paper, the estimation of limit unit bearing capacity of axially loaded circular footings on sands based on cone penetration test cone resistance is examined. There are significant uncertainties in the calculation of bearing capacity using the bearing capacity ...
Journal of Geotechnical and Geoenvironmental Engineering, 2003
Both the driving response and static bearing capacity of open-ended piles are affected by the soi... more Both the driving response and static bearing capacity of open-ended piles are affected by the soil plug that forms inside the pile during pile driving. In order to investigate the effect of the soil plug on the static and dynamic response of an open-ended pile and the load capacity of pipe piles in general, field pile load tests were performed on instrumented open-and closed-ended piles driven into sand. For the open-ended pile, the soil plug length was continuously measured during pile driving, allowing calculation of the incremental filling ratio for the pile. The cumulative hammer blow count for the open-ended pile was 16% lower than for the closed-ended pile. The limit unit shaft resistance and the limit unit base resistance of the open-ended pile were 51 and 32% lower than the corresponding values for the closed-ended pile. It was also observed, for the open-ended pile, that the unit soil plug resistance was only about 28% of the unit annulus resistance, and that the average unit frictional resistance between the soil plug and the inner surface of the open-ended pile was 36% higher than its unit outside shaft resistance.
Journal of Geotechnical and Geoenvironmental Engineering, 2000
The properties of clean sands pertaining to shear strength and stiffness have been studied extens... more The properties of clean sands pertaining to shear strength and stiffness have been studied extensively. However, natural sands generally contain significant amounts of silt and/or clay. The mechanical response of such soils is different from that of clean sands. This paper addresses the effects of nonplastic fines on the small-strain stiffness and shear strength of sands. A series of laboratory tests was performed on samples of Ottawa sand with fines content in the range of 5-20% by weight. The samples were prepared at different relative densities and were subjected to various levels of mean effective consolidation stress. Most of the triaxial tests were conducted to axial strains in excess of 30%. The stress-strain responses were recorded, and the shear strength and dilatancy parameters were obtained for each fines percentage. Bender element tests performed in triaxial test samples allowed assessment of the effect of fines content on small-strain mechanical stiffness.
Computers and Geotechnics, 2015
This paper presents a system probabilistic stability evaluation method for slopes based on Gaussi... more This paper presents a system probabilistic stability evaluation method for slopes based on Gaussian process regression (GPR) and Latin hypercube sampling. The analysis is composed of three parts. Firstly, Latin hypercube sampling is adopted to generate samples for constructing the response surface. Then, based on the samples, Gaussian process regression, which is a popular machine learning technique for nonlinear system modeling, is used for establishing the response surface to approximate the limit state function. Finally, Monte Carlo simulation is performed via the GPR response surface to estimate the system failure probability of slopes. Five case examples were examined to verify the effectiveness of the proposed methodology. Computer simulation results show that the proposed system reliability analysis method can accurately give the system failure probability with a relatively small number of deterministic slope stability analyses.
Drilled displacement piles are being increasingly used as foundation elements, particularly in pr... more Drilled displacement piles are being increasingly used as foundation elements, particularly in projects requiring fast construction. Different types of drilled displacement (DD) piles are available in practice. DD piles are classified according to the drilling tool design and installation method. The capacity of a DD pile, depending on its type, is between the capacities of geometrically similar nondisplacement and full-displacement piles installed in the same soil profile. This paper provides an overview of the different types of DD piles and their installation techniques and describes three design methods used in practice. It also compares DD pile capacities obtained with these design methods for two different sites.
Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Adminis... more Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration.
… on Case Histories …, Jan 1, 2008
When piles are installed by jacking or driving, they cause substantial changes in the state of so... more When piles are installed by jacking or driving, they cause substantial changes in the state of soil located near the pile. These changes result from the complex loading imposed on the soil by expansion of a cylindrical cavity to make room for the pile, by multiple cycles of shearing in the vertical direction as the pile gradually moves down into
Geotechnical design has traditionally been done using working stress design (WSD). Working stress... more Geotechnical design has traditionally been done using working stress design (WSD). Working stress design identifies limit states for a structure, then protects against their occurrence using factors of safety. Load and resistance factor design (LRFD) uses load and resistance factors instead of factors of safety. LRFD also establishes the geotechnical resistance much more precisely than WSD. This research establishes load
Advances in Deep Foundations, 2005
... his Terzaghi Lecture (O'Neill 2001) on pile shaft resistance and the FHWA manual publishe... more ... his Terzaghi Lecture (O'Neill 2001) on pile shaft resistance and the FHWA manual published with Lymon C. Reese (Reese and O'Neil ... FEM analysis using the commercial software ABAQUS was performed to obtain the base resistances of drilled shafts in sandy soils (Lee and ...
Computers and Geotechnics, 2005
Footings are often used to support structures at sites where the soils near the surface are suffi... more Footings are often used to support structures at sites where the soils near the surface are sufficiently strong to serve as a bearing layer. In this study, estimation of the bearing capacity of footings resting on a soil mass acted upon by a surcharge is investigated and related to the cone resistance qc. Non-linear finite element analyses based on a
Journal of Geotechnical and Geoenvironmental Engineering, 2003
... The behavior of open-ended piles is more complex, with a response generally intermediate betw... more ... The behavior of open-ended piles is more complex, with a response generally intermediate between those of nondisplacement and displacement piles. ... The tip displacement of drilled shafts in sands. Proc ... The effect of pile type on design parameters for driven piles. Proc., 7th ...
Journal of Geotechnical and Geoenvironmental Engineering, 2005
In the present paper, the estimation of limit unit bearing capacity of axially loaded circular fo... more In the present paper, the estimation of limit unit bearing capacity of axially loaded circular footings on sands based on cone penetration test cone resistance is examined. There are significant uncertainties in the calculation of bearing capacity using the bearing capacity ...
Journal of Geotechnical and Geoenvironmental Engineering, 2003
Both the driving response and static bearing capacity of open-ended piles are affected by the soi... more Both the driving response and static bearing capacity of open-ended piles are affected by the soil plug that forms inside the pile during pile driving. In order to investigate the effect of the soil plug on the static and dynamic response of an open-ended pile and the load capacity of pipe piles in general, field pile load tests were performed on instrumented open-and closed-ended piles driven into sand. For the open-ended pile, the soil plug length was continuously measured during pile driving, allowing calculation of the incremental filling ratio for the pile. The cumulative hammer blow count for the open-ended pile was 16% lower than for the closed-ended pile. The limit unit shaft resistance and the limit unit base resistance of the open-ended pile were 51 and 32% lower than the corresponding values for the closed-ended pile. It was also observed, for the open-ended pile, that the unit soil plug resistance was only about 28% of the unit annulus resistance, and that the average unit frictional resistance between the soil plug and the inner surface of the open-ended pile was 36% higher than its unit outside shaft resistance.
Journal of Geotechnical and Geoenvironmental Engineering, 2000
The properties of clean sands pertaining to shear strength and stiffness have been studied extens... more The properties of clean sands pertaining to shear strength and stiffness have been studied extensively. However, natural sands generally contain significant amounts of silt and/or clay. The mechanical response of such soils is different from that of clean sands. This paper addresses the effects of nonplastic fines on the small-strain stiffness and shear strength of sands. A series of laboratory tests was performed on samples of Ottawa sand with fines content in the range of 5-20% by weight. The samples were prepared at different relative densities and were subjected to various levels of mean effective consolidation stress. Most of the triaxial tests were conducted to axial strains in excess of 30%. The stress-strain responses were recorded, and the shear strength and dilatancy parameters were obtained for each fines percentage. Bender element tests performed in triaxial test samples allowed assessment of the effect of fines content on small-strain mechanical stiffness.
Computers and Geotechnics, 2015
This paper presents a system probabilistic stability evaluation method for slopes based on Gaussi... more This paper presents a system probabilistic stability evaluation method for slopes based on Gaussian process regression (GPR) and Latin hypercube sampling. The analysis is composed of three parts. Firstly, Latin hypercube sampling is adopted to generate samples for constructing the response surface. Then, based on the samples, Gaussian process regression, which is a popular machine learning technique for nonlinear system modeling, is used for establishing the response surface to approximate the limit state function. Finally, Monte Carlo simulation is performed via the GPR response surface to estimate the system failure probability of slopes. Five case examples were examined to verify the effectiveness of the proposed methodology. Computer simulation results show that the proposed system reliability analysis method can accurately give the system failure probability with a relatively small number of deterministic slope stability analyses.