Excavation support is commonly provided using soil-nailed walls or tie-hack walls. This paper des... more Excavation support is commonly provided using soil-nailed walls or tie-hack walls. This paper describes two case histories where nails and anchors where installed using a hollow reinforcing har and a disposable drill bit. A lean grout was pumped through the reinforcing bar as it was driven into the ground. This process created a reinforced grout column with a diameter of about 150 mm. This procedure reduced the time of installation and resulted in cost savings of about 25?c in comparison with conventional procedures. The procedure was used successfully to install nails in sandy gravels and ~ilty sands. It was also used successfully to install tic-back anchors and the measured horizontal and vertical movements behind the wall were well within acceptable limits. Pull-out tests indicated that the ultimate pull-out resistance of the nails/anchors was between 58.3 to 65.6 kN/m (4 to 4.5 kips/t't) in the gravelly sands and 49.6 kN/m to 56.8 kN/m (3.4 to 3.9 kips/11) in the silly sand (30o/c) tines. The soil-nail approach was not found to be practical where thick sequences of clean sands. were encountered due to surface raveling and caving.
Journal of Geotechnical and Geoenvironmental Engineering, 2010
Lateral pile cap tests were performed on a pile cap with three backfills to evaluate the static a... more Lateral pile cap tests were performed on a pile cap with three backfills to evaluate the static and dynamic behavior. One backfill consisted of loose silty sand while the other two consisted of dense gravel zones 0.91-and 1.82-m wide between the pile cap and the loose silty sand. The 0.91-and 1.82-m wide dense gravel zones increased the lateral resistance by 75 to 150% and 150 to 225%, respectively, relative to the loose silty sand backfill. Despite being thin relative to the overall shear length, the 0.92-and 1.82-m wide gravel zones increase lateral resistance to 59% and 83%, respectively, of the resistance that would be provided by a backfill entirely composed of dense gravel. The dynamic stiffness for the pile cap with the gravel zone decreased about 10% after 15 cycles of loading, while the damping ratio remained relatively constant with cycling. Dynamic stiffness increased by about 10 to 40% at higher deflections, while the damping ratio decreased from an initial value of about 0.30 to around 0.26 at higher deflections.
This study investigated the moment capacity and load-displacement response of the pile-to-cap con... more This study investigated the moment capacity and load-displacement response of the pile-to-cap connection details. Lateral load tests were conducted on four pile caps (3 ft H x 3 ft W x 6.5 ft L) with two 40 foot-long steel pipe piles (12.75 inch OD) with different connection details. Two caps included a reinforced connection detail with six or 12 inch pile embedment while the other two relied exclusively on their respective embedment lengths of 12 and 24 inches. A hydraulic ram was used to apply a cyclic lateral force to each of these pile caps until failure occurred. Load-displacement curves were developed for each cap and bending moments were computed from strain measurements in the piles. The pile cap with piles embedded two diameters (24 inches) into the cap performed successfully. In contrast, a cap with piles embedded only one diameter failed after developing a large crack through the entire cap. The two pile caps with shallow embedment (0.5 to 1.0 diameter) and a reinforcing cage connection still developed at least 40 to 60% of the moment capacity of the pile which was much greater than predicted by PCI design equations based only on embedment. The load-displacement curves and bending moments computed using the computer program GROUP were in very good agreement with measured values when the pile connections were considered to be "fixed-head". However, assuming a "free-head" or pinned connection significantly overestimated displacement even for the connection with only 6 inches of embedment. These results suggest that it is relatively difficult to create a truly pinned connection detail and that some connections which are assumed to be pinned may actually behave more like fixed connections.
ABSTRACT This paper presents three dimensional finite element models of skew-angled bridge abutme... more ABSTRACT This paper presents three dimensional finite element models of skew-angled bridge abutments and their analyses under displacement-control, carried out using PLAXIS 3D software. The objective is to validate the said models against data from large-scale experiments performed at Brigham Young University, which produced direct measurements of load-deformation backbone curves for several skew angles. Validated finite element models are intended for parametric studies for obtaining broadly applicable load-deformation relationships (i.e., those for different wall heights and backfill soil types) that can be routinely used in the seismic design and analysis of skewed bridges. Experimental data as well as the numerical models indicate that the behavior of a skewed abutment is highly nonlinear; the force displacement response is nearly hyperbolic in shape; and there is a significant reduction in passive capacity as the skew angle increases.
For bridges supported by piles, acceptable system performance under seismic loading depends on ef... more For bridges supported by piles, acceptable system performance under seismic loading depends on effective pile-to-cap connections. A fixed pile-to-cap connection is often desirable to help control deflections during lateral loading when soft soils are present. While reinforcement bar cages that extend from the pile into the cap are effective in providing a fixed pile-to-cap connection, it is more economical to rely on pile embedment to provide fixity and moment resistance. This study investigated embedded pile-to-cap connections for concrete-filled pipe piles. Four full-scale specimens, each consisting of a cap with two piles, were investigated in the field under cyclic loading. The specimens had minimal reinforcement and varying amounts of pile embedment. Results show that the moment resistance of pile-to-cap connections can be significantly greater than what is typically calculated based on the flexural reinforcement and embedment bearing. Excess moment capacity may be explained by friction between the p...
Journal of Geotechnical and Geoenvironmental Engineering, Mar 1, 2008
ABSTRACT A study to evaluate corrosion rates was conducted using pile foundations abandoned durin... more ABSTRACT A study to evaluate corrosion rates was conducted using pile foundations abandoned during the reconstruction of 1-15 through Salt Lake Valley, Utah. Corrosion rates were measured for 20 piles extracted from five sites after service lives of 34-38 years. Measurements were made of soil index properties, resistivity, pH, cation/anion concentrations, and water table elevation. The critical zone for corrosion was typically located within the groundwater fluctuation zone; but correlations with soil properties were generally poor. Despite low resistivity, average corrosion rates for pile caps in native soil were typically between 2 and 9 mu m/year with a maximum of 19 mu m/year and did not pose any structural integrity problems. Nevertheless, for abutment piles where chloride concentration was very high, the average pile corrosion rate increased to 13 mu m/year within the embankment and the maximum corrosion rate was 48 mu m/year in the underlying native soil. Based on data from this and previous studies, equations were developed to predict maximum corrosion loss for piles in nonaggressive soil as a function of time.
Journal of Geotechnical and Geoenvironmental Engineering, Aug 1, 1998
The influence of moisture content on dynamic compaction efficiency was evaluated at six field tes... more The influence of moisture content on dynamic compaction efficiency was evaluated at six field test cells, each with a progressively higher average moisture content. The soil profile consisted of collapsible sandy silt, and average test cell moisture contents ranged from 6% to 20%. At each cell, compaction was performed with a 4.54 t weight dropped from a height of 24.3 m. Compaction efficiency was evaluated using (1) crater depth measurements, (2) cone penetration tests before and after compaction, and (3) undisturbed samples before and after compaction. Crater depth increased by a factor of 4 as moisture content increased. The degree of improvement increased up to a moisture content of about 17% and then decreased. The optimum moisture content and the maximum dry unit weight are similar to those predicted by laboratory Proctor testing using energy levels comparable to those employed in the field. Maximum dry unit weight decreased with depth, while optimum moisture content increased before the compactive ...
Journal of Geotechnical and Geoenvironmental Engineering, Sep 1, 2006
Passive Earth Pressure Mobilization during Cyclic Loading. [Journal of Geotechnical and Geoenviro... more Passive Earth Pressure Mobilization during Cyclic Loading. [Journal of Geotechnical and Geoenvironmental Engineering 132, 1154 (2006)]. Ryan T. Cole, Kyle M. Rollins. Abstract. The passive resistance measured in a series ...
Journal of Geotechnical and Geoenvironmental Engineering, 2005
... Because of the high cost of conducting lateral load tests on pile groups, relatively few full... more ... Because of the high cost of conducting lateral load tests on pile groups, relatively few full-scaleload test results are available that show the distribution of load within pile groups in sand. ... SinglePile Lateral Load Test Results and Analysis. Test Layout and Instrumentation. ...
Previously, full-scale lateral load tests conducted on pile caps with different aspect ratios sho... more Previously, full-scale lateral load tests conducted on pile caps with different aspect ratios showed that placement of a narrow, dense backfill zone against the cap could substantially increase the passive resistance. The objective of this study is to develop design equations to predict the increased passive resistance for these limited width backfills for both 2D and 3D conditions. For this purpose, the finite element program, PLAXIS 2D was used to investigate the 2D or plane strain passive resistance. To validate the procedure, numerical results were calibrated against analytical results obtained from PYCAP and ABUTMENT. The analytical models were additionally validated by comparison with measured ultimate passive resistances. The calibrated model was then used to simulate the passive behavior of limited width gravel backfills. Parametric studies were also executed to evaluate the influence of a range of selected design parameters, related to the pile cap geometry and backfill soil type, on the passive resistance of limited width backfills. Numerical results indicated that significant increases in passive resistance could be expected for long abutment walls where end effects are less pronounced and the geometry is closer to a plane strain condition. Based on results obtained from the parametric studies, a design method was developed for predicting the ultimate passive resistance of limited width backfills, for both plane strain and 3D geometries. Comparisons between measured and numerical results indicated that using the Brinch-Hansen 3D correction factor, R 3D , as a multiplier to the plane strain resistances, will provide a conservative estimate of the actual 3D passive response of a pile cap with a limited width backfill.
The Manning Canyon shale formation underlies many of the slopes adjacent to the Wasatch mountain ... more The Manning Canyon shale formation underlies many of the slopes adjacent to the Wasatch mountain range near Provo, Utah. The climate in Utah is relatively dry, so the strength of the shale is normally sufficient to prevent slope instability. During wet periods, however, the shale exhibits a significant decrease in strength that has led to a number of landslides. One method that has been employed to stabilize some of the slopes is the installation of closely spaced drilled shafts. Successful application of this stabilization procedure requires (a) accurate evaluations of the geometry and strength of the materials composing the slope, (b) reasonable evaluations of the location of potential failure surfaces, (c) estimations of the horizontal force required to increase the factor of safety against sliding to a suitable value, and (d) design and construction of drilled shafts capable of resisting the required horizontal force. The application of the method is illustrated with the use of several case histories for slopes on which slides have developed. Continued sliding threatened homes upslope and closed roadways to traffic. The success of the stabilization technique was recently proved in one of the cases in which the slope behind the drilled-shaft wall became wet. Although a slide developed in the slope immediately adjacent to the wall, the slope behind the wall has remained stable. Damage to the homes and roadways because of the movement of the slides has been arrested since the walls were constructed.
This proceedings, In-Situ Deep Soil Improvement , contains papers presented at sessions sponsored... more This proceedings, In-Situ Deep Soil Improvement , contains papers presented at sessions sponsored by the Geotechnical Engineering Division of ASCE in conjunction with the ASCE National Convention in Atlanta, Georgia, October 9-13, 1994. They mainly discuss the use of deep dynamic compaction for densification of collapsible soils, liquefiable soils and waste materials, and provide a practical summary of what has been learned regarding the potential for improvement in these materials. In addition to the topic of dynamic compaction, other methods for in-situ soil improvement, such as stone columns, deep soil mixing, and vacuum consolidation, are presented.
Excavation support is commonly provided using soil-nailed walls or tie-hack walls. This paper des... more Excavation support is commonly provided using soil-nailed walls or tie-hack walls. This paper describes two case histories where nails and anchors where installed using a hollow reinforcing har and a disposable drill bit. A lean grout was pumped through the reinforcing bar as it was driven into the ground. This process created a reinforced grout column with a diameter of about 150 mm. This procedure reduced the time of installation and resulted in cost savings of about 25?c in comparison with conventional procedures. The procedure was used successfully to install nails in sandy gravels and ~ilty sands. It was also used successfully to install tic-back anchors and the measured horizontal and vertical movements behind the wall were well within acceptable limits. Pull-out tests indicated that the ultimate pull-out resistance of the nails/anchors was between 58.3 to 65.6 kN/m (4 to 4.5 kips/t't) in the gravelly sands and 49.6 kN/m to 56.8 kN/m (3.4 to 3.9 kips/11) in the silly sand (30o/c) tines. The soil-nail approach was not found to be practical where thick sequences of clean sands. were encountered due to surface raveling and caving.
Journal of Geotechnical and Geoenvironmental Engineering, 2010
Lateral pile cap tests were performed on a pile cap with three backfills to evaluate the static a... more Lateral pile cap tests were performed on a pile cap with three backfills to evaluate the static and dynamic behavior. One backfill consisted of loose silty sand while the other two consisted of dense gravel zones 0.91-and 1.82-m wide between the pile cap and the loose silty sand. The 0.91-and 1.82-m wide dense gravel zones increased the lateral resistance by 75 to 150% and 150 to 225%, respectively, relative to the loose silty sand backfill. Despite being thin relative to the overall shear length, the 0.92-and 1.82-m wide gravel zones increase lateral resistance to 59% and 83%, respectively, of the resistance that would be provided by a backfill entirely composed of dense gravel. The dynamic stiffness for the pile cap with the gravel zone decreased about 10% after 15 cycles of loading, while the damping ratio remained relatively constant with cycling. Dynamic stiffness increased by about 10 to 40% at higher deflections, while the damping ratio decreased from an initial value of about 0.30 to around 0.26 at higher deflections.
This study investigated the moment capacity and load-displacement response of the pile-to-cap con... more This study investigated the moment capacity and load-displacement response of the pile-to-cap connection details. Lateral load tests were conducted on four pile caps (3 ft H x 3 ft W x 6.5 ft L) with two 40 foot-long steel pipe piles (12.75 inch OD) with different connection details. Two caps included a reinforced connection detail with six or 12 inch pile embedment while the other two relied exclusively on their respective embedment lengths of 12 and 24 inches. A hydraulic ram was used to apply a cyclic lateral force to each of these pile caps until failure occurred. Load-displacement curves were developed for each cap and bending moments were computed from strain measurements in the piles. The pile cap with piles embedded two diameters (24 inches) into the cap performed successfully. In contrast, a cap with piles embedded only one diameter failed after developing a large crack through the entire cap. The two pile caps with shallow embedment (0.5 to 1.0 diameter) and a reinforcing cage connection still developed at least 40 to 60% of the moment capacity of the pile which was much greater than predicted by PCI design equations based only on embedment. The load-displacement curves and bending moments computed using the computer program GROUP were in very good agreement with measured values when the pile connections were considered to be "fixed-head". However, assuming a "free-head" or pinned connection significantly overestimated displacement even for the connection with only 6 inches of embedment. These results suggest that it is relatively difficult to create a truly pinned connection detail and that some connections which are assumed to be pinned may actually behave more like fixed connections.
ABSTRACT This paper presents three dimensional finite element models of skew-angled bridge abutme... more ABSTRACT This paper presents three dimensional finite element models of skew-angled bridge abutments and their analyses under displacement-control, carried out using PLAXIS 3D software. The objective is to validate the said models against data from large-scale experiments performed at Brigham Young University, which produced direct measurements of load-deformation backbone curves for several skew angles. Validated finite element models are intended for parametric studies for obtaining broadly applicable load-deformation relationships (i.e., those for different wall heights and backfill soil types) that can be routinely used in the seismic design and analysis of skewed bridges. Experimental data as well as the numerical models indicate that the behavior of a skewed abutment is highly nonlinear; the force displacement response is nearly hyperbolic in shape; and there is a significant reduction in passive capacity as the skew angle increases.
For bridges supported by piles, acceptable system performance under seismic loading depends on ef... more For bridges supported by piles, acceptable system performance under seismic loading depends on effective pile-to-cap connections. A fixed pile-to-cap connection is often desirable to help control deflections during lateral loading when soft soils are present. While reinforcement bar cages that extend from the pile into the cap are effective in providing a fixed pile-to-cap connection, it is more economical to rely on pile embedment to provide fixity and moment resistance. This study investigated embedded pile-to-cap connections for concrete-filled pipe piles. Four full-scale specimens, each consisting of a cap with two piles, were investigated in the field under cyclic loading. The specimens had minimal reinforcement and varying amounts of pile embedment. Results show that the moment resistance of pile-to-cap connections can be significantly greater than what is typically calculated based on the flexural reinforcement and embedment bearing. Excess moment capacity may be explained by friction between the p...
Journal of Geotechnical and Geoenvironmental Engineering, Mar 1, 2008
ABSTRACT A study to evaluate corrosion rates was conducted using pile foundations abandoned durin... more ABSTRACT A study to evaluate corrosion rates was conducted using pile foundations abandoned during the reconstruction of 1-15 through Salt Lake Valley, Utah. Corrosion rates were measured for 20 piles extracted from five sites after service lives of 34-38 years. Measurements were made of soil index properties, resistivity, pH, cation/anion concentrations, and water table elevation. The critical zone for corrosion was typically located within the groundwater fluctuation zone; but correlations with soil properties were generally poor. Despite low resistivity, average corrosion rates for pile caps in native soil were typically between 2 and 9 mu m/year with a maximum of 19 mu m/year and did not pose any structural integrity problems. Nevertheless, for abutment piles where chloride concentration was very high, the average pile corrosion rate increased to 13 mu m/year within the embankment and the maximum corrosion rate was 48 mu m/year in the underlying native soil. Based on data from this and previous studies, equations were developed to predict maximum corrosion loss for piles in nonaggressive soil as a function of time.
Journal of Geotechnical and Geoenvironmental Engineering, Aug 1, 1998
The influence of moisture content on dynamic compaction efficiency was evaluated at six field tes... more The influence of moisture content on dynamic compaction efficiency was evaluated at six field test cells, each with a progressively higher average moisture content. The soil profile consisted of collapsible sandy silt, and average test cell moisture contents ranged from 6% to 20%. At each cell, compaction was performed with a 4.54 t weight dropped from a height of 24.3 m. Compaction efficiency was evaluated using (1) crater depth measurements, (2) cone penetration tests before and after compaction, and (3) undisturbed samples before and after compaction. Crater depth increased by a factor of 4 as moisture content increased. The degree of improvement increased up to a moisture content of about 17% and then decreased. The optimum moisture content and the maximum dry unit weight are similar to those predicted by laboratory Proctor testing using energy levels comparable to those employed in the field. Maximum dry unit weight decreased with depth, while optimum moisture content increased before the compactive ...
Journal of Geotechnical and Geoenvironmental Engineering, Sep 1, 2006
Passive Earth Pressure Mobilization during Cyclic Loading. [Journal of Geotechnical and Geoenviro... more Passive Earth Pressure Mobilization during Cyclic Loading. [Journal of Geotechnical and Geoenvironmental Engineering 132, 1154 (2006)]. Ryan T. Cole, Kyle M. Rollins. Abstract. The passive resistance measured in a series ...
Journal of Geotechnical and Geoenvironmental Engineering, 2005
... Because of the high cost of conducting lateral load tests on pile groups, relatively few full... more ... Because of the high cost of conducting lateral load tests on pile groups, relatively few full-scaleload test results are available that show the distribution of load within pile groups in sand. ... SinglePile Lateral Load Test Results and Analysis. Test Layout and Instrumentation. ...
Previously, full-scale lateral load tests conducted on pile caps with different aspect ratios sho... more Previously, full-scale lateral load tests conducted on pile caps with different aspect ratios showed that placement of a narrow, dense backfill zone against the cap could substantially increase the passive resistance. The objective of this study is to develop design equations to predict the increased passive resistance for these limited width backfills for both 2D and 3D conditions. For this purpose, the finite element program, PLAXIS 2D was used to investigate the 2D or plane strain passive resistance. To validate the procedure, numerical results were calibrated against analytical results obtained from PYCAP and ABUTMENT. The analytical models were additionally validated by comparison with measured ultimate passive resistances. The calibrated model was then used to simulate the passive behavior of limited width gravel backfills. Parametric studies were also executed to evaluate the influence of a range of selected design parameters, related to the pile cap geometry and backfill soil type, on the passive resistance of limited width backfills. Numerical results indicated that significant increases in passive resistance could be expected for long abutment walls where end effects are less pronounced and the geometry is closer to a plane strain condition. Based on results obtained from the parametric studies, a design method was developed for predicting the ultimate passive resistance of limited width backfills, for both plane strain and 3D geometries. Comparisons between measured and numerical results indicated that using the Brinch-Hansen 3D correction factor, R 3D , as a multiplier to the plane strain resistances, will provide a conservative estimate of the actual 3D passive response of a pile cap with a limited width backfill.
The Manning Canyon shale formation underlies many of the slopes adjacent to the Wasatch mountain ... more The Manning Canyon shale formation underlies many of the slopes adjacent to the Wasatch mountain range near Provo, Utah. The climate in Utah is relatively dry, so the strength of the shale is normally sufficient to prevent slope instability. During wet periods, however, the shale exhibits a significant decrease in strength that has led to a number of landslides. One method that has been employed to stabilize some of the slopes is the installation of closely spaced drilled shafts. Successful application of this stabilization procedure requires (a) accurate evaluations of the geometry and strength of the materials composing the slope, (b) reasonable evaluations of the location of potential failure surfaces, (c) estimations of the horizontal force required to increase the factor of safety against sliding to a suitable value, and (d) design and construction of drilled shafts capable of resisting the required horizontal force. The application of the method is illustrated with the use of several case histories for slopes on which slides have developed. Continued sliding threatened homes upslope and closed roadways to traffic. The success of the stabilization technique was recently proved in one of the cases in which the slope behind the drilled-shaft wall became wet. Although a slide developed in the slope immediately adjacent to the wall, the slope behind the wall has remained stable. Damage to the homes and roadways because of the movement of the slides has been arrested since the walls were constructed.
This proceedings, In-Situ Deep Soil Improvement , contains papers presented at sessions sponsored... more This proceedings, In-Situ Deep Soil Improvement , contains papers presented at sessions sponsored by the Geotechnical Engineering Division of ASCE in conjunction with the ASCE National Convention in Atlanta, Georgia, October 9-13, 1994. They mainly discuss the use of deep dynamic compaction for densification of collapsible soils, liquefiable soils and waste materials, and provide a practical summary of what has been learned regarding the potential for improvement in these materials. In addition to the topic of dynamic compaction, other methods for in-situ soil improvement, such as stone columns, deep soil mixing, and vacuum consolidation, are presented.
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Papers by Kyle Rollins