Characterization Of T Z Model Design Parameters For Augered Cast In Place Piles Using Field Load Test Data
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Characterization Of T Z Model Design Parameters For Augered Cast In Place Piles Using Field Load Test Data
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Author : Bradley Scott Gardner
language : en
Publisher:
Release Date : 2012
Characterization Of T Z Model Design Parameters For Augered Cast In Place Piles Using Field Load Test Data written by Bradley Scott Gardner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Concrete piling categories.
With the increasing use of augered cast-in-place piles in new construction, it is important that proper design parameters be incorporated when evaluating pile capacity and performance using reliability-based design methods. This paper focuses on developing "t-z" model parameters from analysis of static axial compression and tension load test data from a project site along the Missouri River floodplain in northwest Missouri. Data was collected from a total of twelve axial load tests (six compression and six tension) and includes dial gauge readings from the pile heads as well as vibrating wire strain gauge data from multiple locations throughout several of the test piles. The "t-z" method has been used extensively as a soil-structure interaction model to evaluate the settlement of deep foundations. The soil-structure interaction modeled in this analysis was based on hyperbolic load displacement behavior using effective (drained) stresses. The development of the "t-z" model parameters has been accomplished using finite difference methods to analyze the non-linear soil-structure interaction along the sides of the piles. During the analysis, the mean shear modulus of soil-structure interface subgrade reaction, K[sub]init, and the mean ultimate shear strength of the soil-structure interface, [symbol for tau][sub]u, were back-calculated from each set of load test data and were based on the assumption of a single-layer, homogenous soil profile. These "t-z" model parameters were then compared to standard field investigation data, including standard penetration tests (SPT) and cone penetrometer test (CPT) soundings, and effective overburden stress to develop correlations suitable for service limit state design of augered cast-in-place piles. While there was some indication of a linear relationship between K[sub]init and the field investigation data, there was not a sufficient quantity of data in the analysis to properly identify any statistical trends. The relationship between [symbol for tau][sub]u and the field investigation data was much more variable and did not provide any distinct correlation. The plot of the data relating the model parameters to the effective overburden stress exhibited some grouping but the sample size and distribution was not sufficient to identify any statistical trends.
A Comparison Of Load Test Data And Predicted Behavior Of Auger Cast Piles In Layered Soils
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Author : John Michael Hudson
language : en
Publisher:
Release Date : 2008
A Comparison Of Load Test Data And Predicted Behavior Of Auger Cast Piles In Layered Soils written by John Michael Hudson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Piling (Civil engineering) categories.
The use of auger cast-in-place (ACIP) pilings is very common in Florida; however, there is a significant degree of uncertainty in determining the actual capacity of the pilings, especially when the pilings are installed through layers of cohesive soils. Therefore, there is a need to improve upon the existing methods of predicting the behavior of ACIP piles in layered soils. As a result, the primary objective of this study is to determine if a significant difference exists between the accepted methods of pile load test analysis. Provided a significant difference is noted, the secondary objective would be to determine if an improvement could be made to enhance the existing empirical relationships used to predict pile behavior in layered soils. In order to accomplish these objectives, this study presents an evaluation of some of the most commonly used methods for predicting ACIP pile capacity based upon the results of actual field load tests. Data from twenty-five load tests were analyzed using popular methods and statistical analyses were preformed to determine and evaluate the data. These evaluations were utilized to explore correlations between predicted behavior and actual results. Based upon the results of this study, there is no statistically significant difference between the load test analyses methods examined. As a result, no improvement to the existing methods of predicting ACIP pile behavior in layered soils may be recommended at this time, and further research in this subject matter is recommended.
Load Transfer Criteria For Numerical Analysis Of Axially Loaded Piles In Sand Part 1 Load Transfer Criteria
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Author : R. L. Mosher
language : en
Publisher:
Release Date : 1984
Load Transfer Criteria For Numerical Analysis Of Axially Loaded Piles In Sand Part 1 Load Transfer Criteria written by R. L. Mosher and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1984 with categories.
Part I describes a study of load-transfer criteria for analysis of axially loaded piles in sand using the discrete springs soil model. Various analysis methods for axially loaded piles are presented, along with a literature review of pile behavior in sands focusing on the changes the soil undergoes during pile installation. Available criteria for spring representation of soil are presented and summarized. The criteria are compated with actual field data from pile load tests and are critically evaluated based on these comparisons. Because of the poor performance of the available criteria, new criteria are proposed. The new criteria use maximum side and tip resistance values presented by Castello (1980). Castello's values are modified by the author to reflect the field data from the Lower Mississippi Valley. Displacement functions for side and tip resistance are developed based on correlations with field data for pile load tests. The new criteria are evaluated against pile load test data. Use of the critieria is demonstrated in an outline of an analysis. The new criteria are used to develop a set of design curves for the practicing engineer. Part II of this report is published under a separate cover, and presents load capacity curves for select steel and concrete pile.
Assessment Of Axially Loaded Pile Dynamic Design Methods And Review Of Indot Axially Loaded Pile Design Procedure
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Author : Dimitrios Loukidis
language : en
Publisher: Purdue University Press
Release Date : 2008-03-01
Assessment Of Axially Loaded Pile Dynamic Design Methods And Review Of Indot Axially Loaded Pile Design Procedure written by Dimitrios Loukidis and has been published by Purdue University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-03-01 with Transportation categories.
The general aim of the present research is to identify areas of improvement and propose changes in the current methodologies followed by INDOT for design of axially loaded piles, with special focus on the dynamic analysis of pile driving. Interviews with INDOT geotechnical engineers and private geotechnical consultants frequently involved in INDOT's deep foundation projects provided information on the methods and software currently employed. It was found that geotechnical engineers rely on static unit soil resistance equations that were developed over twenty years ago and that have a relatively large degree of empiricism. Updated and improved static design equations recently proposed in the literature have not yet been implemented in practice. Pile design relies predominantly on SPT data; cone penetration testing is performed only occasionally. Dynamic analysis of pile driving in standard practice is performed using Smith-type soil reaction models. A comprehensive review of existing soil reaction models for 1-dimensional dynamic pile analysis is presented. This review allowed an assessment of the validity of existing models and identification of their limitations. New shaft and base reaction models are developed that overcome shortcomings of existing models and that are consistent with the physics and mechanics of pile driving.
Determination Of P Y Curves By Direct Use Of Cone Penetration Test Cpt Data
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Author : SHAWN SHAHRIAR ARIANNIA
language : en
Publisher:
Release Date : 2015
Determination Of P Y Curves By Direct Use Of Cone Penetration Test Cpt Data written by SHAWN SHAHRIAR ARIANNIA and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The current best practice in geotechnical engineering in determining lateral capacity of piles is to replace the soil reaction with a series of independent springs. Basically, the model uses beam theory to represent the pile and uncoupled, non-linear load transfer functions, called p-y curves to represent the soil. Most of the existing methods for determining p-y curves are highly empirical, based on a limited number of cases of laterally loaded piles, which were instrumented, enabling to measure the pile deflection in discrete depth intervals subject to different lateral load (i.e. Matlock 1970, Reese 1975). In essence, these methods have their own limitations, and are mainly applicable for the conditions similar to the tested conditions. Although later, more detailed investigations by different people addressed some of the problems, still the basis of the existing design programs such as LPILE, or procedures introduced in applicable codes such as API (American Petroleum Institute), is the same original recommendations made by Matlock and Reese during seventies. In recent era, demand in employment of in-situ direct-pushed based methods using multi-measurement in-situ devices, such as the seismic cone penetration test with pore water measurement (SCPTu) and Seismic Flat Dilatometer Test (SDMT) is significantly increased. The main objective of this research is to introduce a unified CPT-based approach for determining p-y curves and pile responses to lateral loads. The suggested approach will provide explicit and defined steps/criteria to develop p-y curves for piles subjected to lateral loads using CPT data. CPT data will be used to determine soil strength parameters. Recent developments in relating CPT data to soil basic parameters using Critical State Soil Mechanics (CSSM) framework will be implemented in the suggested model. In all current common models, pre-determination of the soil behavior and the model to be used (e.g. Matlock clay, 1970 or Reese sand, 1975), will become warranted even before commencement of the analysis. On the contrary, in the proposed model, the need for the said pre-determination of soil behavior is eliminated. As discussed in Section 2.3.5, soil behavior in the model is being classified into four broad and general groups: drained-dilative, drained- contractive, undrained-dilative and undrained-contractive The main factor driving the suggested analytical approach is Soil Behavior Type Index, Ic. In the proposed approach, the SBT index, Ic, will be used to determine the in-situ characteristics and behavior of the soil. Based on the value of Ic calculated from CPT data, it could be determined that the soil behaves as a sand-like or a clay-like soil, and during the shearing would behave in undrained or drained condition. The measured shear wave velocity during field test using seismic cone penetration test or other methods such as SASW (Spectral Analysis of Surface Waves) or Cross-Hole logging, may be used to determine the small strain shear modulus, G0, which corresponds to the initial stiffness of the linear part of the p-y curve. In this research, the proposed model will be verified using collected case histories of laterally loaded piles with available CPT data at the same site. The p-y curves, and pile force-head displacements determined from the model will be compared to the field-resulted p-y curves and pile head displacement measurements available from the case histories.
Lateral Load Capacity Of Single Piles Socketed Into Melbourne Mudstone
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Author : Wai Loong Chong
language : en
Publisher:
Release Date : 2011
Lateral Load Capacity Of Single Piles Socketed Into Melbourne Mudstone written by Wai Loong Chong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Industrial practice often adopts analytical methods developed for soils based on the continuum approach when designing laterally-loaded piles socketed into rock mass. High safety considerations and the uncertainties arising from the assumption of continuum rock mass may produce inefficient and unsafe design solutions to foundation problems subjected to lateral loads. To date, the research in the area of laterally-loaded rock-socketed piles has not been advanced sufficiently. The available analytical methods assume rocks to be intact and homogenous materials, and the physical effect of joints is not taken into account. Therefore, this study aims to develop an analytical method for laterally-loaded piles socketed into rock mass incorporating the physical effect of joints. A three-dimensional distinct element code, 3DEC, was utilised to simulate the behaviour of laterally-loaded piles socketed into mudstone rock. The capability of 3DEC to model jointed rock mass was first examined by simulating the confined (triaxial) and unconfined (uniaxial compressive test) loading conditions. The results obtained from this modelling were compared with existing empirical relationships and field test data. 3DEC was then employed to simulate laboratory-scale model pile-load tests. A comprehensive parametric study was carried out based on the calibrated laboratory 3DEC model. It was found that the most influential parameters impacting the lateral behaviour of piles socketed into jointed mudstone are rock modulus, pile diameter, pile bending stiffness, pile socket length, joint dip angle and spacing. Based on the understanding of the key influential parameters affecting lateral load behaviour, 3DEC modelling was extended further to simulate full-scale pile load tests conducted in Melbourne mudstone. Based on extensive numerical modelling, the p-y behaviour of piles socketed into mudstone was derived. It was found that a single p-y curve for mudstone accurately predicts pile-head load-deflection behaviour. Subsequently, a thorough parametric study based on full-scale models was carried out to study the effect of joints on the lateral load capacity of piles. This study found that joint sets in different directions have a significant impact on the p-y and the corresponding pile-head load-deflection behaviour. The worst-case condition of four joint sets reduces the load-carrying capacity of the pile by more than 90% compared to a homogenous mudstone. This is due to the deformation mechanisms of the pile-rock system such as the formation of weak wedges/pyramid blocks around the pile. The results obtained from the extensive parametric study were integrated in the derivation of new p-y criteria for laterally-loaded piles socketed into homogenous and jointed mudstone rocks. The p-y criteria developed require basic rock properties which can be conveniently obtained in the laboratory or using the well-established empirical relationships for mudstone based on water content. The p-y criterion proposed for homogenous mudstone condition was validated using the results of another two field pile-load tests. For the p-y criterion of jointed mudstone, a field load test of a pile with an apparent steep joint in the vicinity of the pile was employed to validate its accuracy. It was found that the p-y criterion for jointed mudstone gives a slightly more conservative prediction of the pile-head load-deflection response. It is suggested that the p-y criterion for homogenous and jointed mudstone conditions will provide the upper and lower bound solutions, respectively. This study has successfully developed an analytical method for laterally-loaded piles socketed into mudstone. The proposed design approach pioneers the integration of the physical effect of joints on the p-y behaviour of piles socketed into jointed mudstone. The proposed p-y criteria were validated using field pile load tests and very close predictions were achieved.
Modeling Pile Setup For Closed Ended Pipe Piles Driven In Cohesive Soils
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Author : Saeed Alzahrani
language : en
Publisher:
Release Date : 2023
Modeling Pile Setup For Closed Ended Pipe Piles Driven In Cohesive Soils written by Saeed Alzahrani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
This research study focuses on modeling pile setup for closed-ended pipe piles (CEP) driven in cohesive soils. Pile setup can be defined as an increase in pile resistance over time after installation due to an increase in soil resistance. Pile setup was rarely considered in the Ohio Department of Transportation, ODOT, standard driven pile design procedures. If significant pile driving losses occur during pile installation, either pile driving is halted for a short period of time to determine whether pile setup will occur, or pile length is increased to achieve the required ultimate bearing value. This would negatively affect not only the piling and projects costs, but also the project schedule. Thus, incorporating pile setup into the design stage can lead to saving in pile quantity and avoid construction delays, as well as help to avoid change orders. In order to better predict pile driving losses during design stage, this research project aimed to develop more reliable pile setup models. To fulfill the objectives of this research, a database was established to collect data from existing projects in the State of Ohio. In addition, several field projects were selected to investigate the pile setup phenomenon. Comprehensive statistical analyses were conducted to investigate the mechanism of pile setup. Effect of the construction activities on the resistance of adjacent piles was also investigated by performing dynamic and static load tests on CEP piles driven in a fine-grained soil profile. The cone penetration tests (CPT) were performed at three locations at the project sites to gain more knowledge of the soil layers. Data obtained from piezometer measurements showed an increase in water pressure at the site during pile driving, which in turn reduced the effective soil strength. This investigation revealed that pile driving and restrikes should be scheduled such that the effect of construction activities on load tests results will be avoided or minimized. This could be implemented by conducting the dynamic load test on the first pile driven at a site and avoiding any construction activities until after the time of the restrike. The effect of construction activities on the resistances of adjacent piles was observed at distances of seven times the pile diameter. The results also indicated that silty clay soil exhibits higher setup than other soil types encountered at the project site. Side and tip resistances obtained from the static load tests were compared with estimates made using well-known CPT-based pile design methods. Overall, these methods achieved satisfactory predictions of the side and tip resistances with some exceptions. Multiple variable regression analyses performed by using the dataset compiled showed that the resistance mobilized at the end of pile installation, time passed after the installation, pile shaft surface area, and average silt content along the pile length are the most influential parameters in predicting the total pile resistance of driven piles. Multiple regression analyses were also carried out by using the collected database of side resistance demonstrated that initial side resistance, time passed since installation, soil volume displaced, clay and water contents along the pile length are the significant variables on predicting pile side resistance. New models for total and side resistances were developed to predict pile setup for CEP piles driven in fine-grained soils using gene expression programming (GEP). The results showed that the proposed models of pile total and side resistances can predict pile setup quite well. An attempt to evaluate the setup, for both total and side resistances, with time using the database has been made. The total and side setup ratios were also analyzed based on various restrike times. Since the database contains piles with multiple restrikes, another analysis was carried out to evaluate the ultimate total and side setup ratios. One of the main goals of this research was to evaluate pile side setup for individual layers using the unit side resistance with the aid of available dynamic load test data. Effect of soil properties on setup ratios for individual soil layers was also investigated. The results revealed that the recommended setup factor for the pile total and side setup ratios of 2.0 and 3.0, respectively, would cover almost all the piles' long term behavior. The results also showed that side friction setup factors for the piles driven in fine-grained Ohio soils are about 50 to 100% more than the factors currently recommended in the ODOT Bridge Design Manual.
Development Of An Acip Pile Specific Load Displacement Model
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Author : Nasim Adami
language : en
Publisher:
Release Date : 2013
Development Of An Acip Pile Specific Load Displacement Model written by Nasim Adami and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Concrete piling categories.
Augered cast-in-place piles, also known as ACIP piles, have been used for more than seven decades in the United States and have gained in popularity due to their relatively quick installation and cost-effectiveness. Owing to the reduced impact on the neighboring environment as compared to some other deep foundation installation methods, ACIP piles are appropriate for use in urban areas. Although there has been an increase in application of ACIP piles, relatively little research on this type of pile has been performed as compared to similar deep foundations, such as drilled shafts. The insufficient experimental work on ACIP pile behavior and lack of ACIP pile specific load- displacement models have led practicing engineers to use the results and methodologies from drilled shafts. An example of this is the use of t-z and q-z based load transfer models from drilled shaft-specific relationships to estimate the load-displacement behavior of ACIP piles. Such applications can result in an underestimation of shaft resistance and consequently disagreement between the predicted and measured load-displacement behavior of the ACIP piles. This thesis evaluates the ability of currently used load-displacement models to estimate the measured load-displacement behavior of ACIP piles. Also, a new empirically-based ACIP pile-specific t-z model is proposed that, in combination with the O'Neill and Reese (1999) q-z model and ACIP pile-specific toe bearing resistance model, forms an ACIP pile specific load-displacement model. Experiments of instrumented ACIP piles installed in the granular soils of Western Washington were used to develop the ACIP pile specific t-z model. Comparison between the results from the currently used load-displacement models with the proposed model showed that the proposed model provides an improvement in the prediction of the load-displacement behavior of ACIP piles. Finally, an analysis of variability is performed using the Monte Carlo Simulation with the sample probability distributions of the uncertain variables in load-displacement model. These analyses result in provide a set of possible loads for a number of common service level displacements, which are reported as cumulative density function (CDF) curves. The CDF curves for loads corresponding to a displacement considered can be a useful tool in design procedure of ACIP piles.
Termination Criteria For High Capacity Jacked And Driven Steel H Pilesin Hong Kong
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Author : Joley Lam
language : en
Publisher: Open Dissertation Press
Release Date : 2017-01-27
Termination Criteria For High Capacity Jacked And Driven Steel H Pilesin Hong Kong written by Joley Lam and has been published by Open Dissertation Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-27 with categories.
This dissertation, "Termination Criteria for High-capacity Jacked and Driven Steel H-pilesin Hong Kong" by Joley, Lam, 林早妮, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Termination Criteria for High-capacity Jacked and Driven Steel H-piles in Hong Kong Submitted by Joley Lam for the degree of Doctor of Philosophy at The University of Hong Kong in June 2007 In recent years, steel H-piles with high yield strength have routinely been used in Hong Kong in foundation systems, but well-accepted installation procedures have yet to be developed for jacked and driven steel H-piles. Jacked piling was recently introduced into Hong Kong with no well-established termination criteria, and many construction problems have yet to be resolved. Field measurements indicate that pile buckling is caused by loss of lateral constraint after deep voids have been formed on both sides of the webs of H-piles. To address this problem, an analytical method has been developed for assessing the critical depth of void at which pile buckling may occur. A sand filling technique has also been developed to limit the void depth and hence prevent buckling of the jacked H-piles. A systematic study has been made to investigate the settlement behaviour of high-capacity jacked H-piles under various loading conditions in order to develop termination criteria for the piles to meet the stringent residual settlement limit for loading test in Hong Kong. The results indicate that preloading the piles by a load equal to 2.3 to 2.4 times the design working capacity (WL) for about half an hour during installation can effectively reduce the creep settlement of jacked piles installed in weathered granites, and hence reduce the residual settlement that would occur after completion of the loading test to a value small enough to meet the acceptance criterion. This is called "pre-creeping" in the thesis. It is also demonstrated that repeated jacking is needed during pile installation to avoid sudden and large pile settlement when the installed pile is subsequently reloaded during loading test or construction of superstructure. For the driven H-piles, the termination criteria established decades ago are incompatible with the advanced pile driving equipment and the pile acceptance criteria adopted nowadays, creating many pile driving problems in Hong Kong. Extensive PDA tests have been conducted to verify that the existing applicable range of the allowable set of 25 to 50 mm per 10 blows is of little use in controlling pile driving stress. The results indicate that piles with C + C values (in millimetre) p q greater than 1.2 times pile length L (in metre) are susceptible to high driving stress. A simple rule for controlling pile driving stress was therefore developed by limiting the C + C values of piles to below 1.2 L. p q It is proposed to adopt the energy approach formula, which uses the impact energy determined by PDA tests to address the limitations of the Hiley formula for calculating the final set table for driven piles in Hong Kong. The energy capacity predictions are reasonably accurate, as confirmed by loading test data from various sites in Hong Kong. Local contractors usually drive the piles to a very small final set to ensure that the installed piles will meet the stringent residual settlement limit. An analysis of the local load test data indicates that piles should achieve a predicted capacity of at least 2.3 to 2.8WL to achieve desirable results. This provides a practical rule for
Design Of Pile Foundations
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Author : Aleksandar Sedmak Vesić
language : en
Publisher: Transportation Research Board
Release Date : 1977-01-01
Design Of Pile Foundations written by Aleksandar Sedmak Vesić and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977-01-01 with Foundations categories.