Improvement Of The Geotechnical Axial Design Methodology For Colorado S Drilled Shafts Socketed In Weak Rocks
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Improvement Of The Geotechnical Axial Design Methodology For Colorado S Drilled Shafts Socketed In Weak Rocks
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Author : Naser Abu-Hejleh
language : en
Publisher:
Release Date : 2003
Improvement Of The Geotechnical Axial Design Methodology For Colorado S Drilled Shafts Socketed In Weak Rocks written by Naser Abu-Hejleh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Axial loads categories.
As a part of the construction requirements for the T-REX and I-25/Broadway projects along I-25 in Denver, Colorado, four Osterberg (O-Cell) load tests on drilled shafts were performed in 2002. The bedrock at the load test sites represents the range of typical claystone and sandstone (soft to very hard) encountered in the Denver metro area. To maximize the benefits of this work, the O-Cell load test results and information on the construction and materials of the test shafts were documented, and an extensive program of simple geotechnical tests was performed on the weak rock at the load test sites. This includes standard penetration tests, strength tests, and pressuremeter tests. The analysis of the test data and information and experience gained in this study were employed to provide: 1) best correlation equations between results of various simple geotechnical tests; 2) best-fit design equations to predict the shaft ultimate unit base and side resistance values, and the load-settlement curve as a function of the results of simple geotechnical tests; and 3) assessment of the CDOT and AASHTO design methods.
Rock Socketed Shafts For Highway Structure Foundations
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Author : John P. Turner
language : en
Publisher: Transportation Research Board
Release Date : 2006
Rock Socketed Shafts For Highway Structure Foundations written by John P. Turner 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 2006 with Bridges categories.
TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 360: Rock-Socketed Shafts for Highway Structure Foundations explores current practices pertaining to each step of the design process, along with the limitations; identifies emerging and promising technologies; examines the principal challenges in advancing the state of the practice; and investigates future developments and potential improvements in the use and design of rock-socketed shafts.
Advances In Deep Foundations
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Author : Yoshiaki Kikuchi
language : en
Publisher: Taylor & Francis
Release Date : 2007-06-21
Advances In Deep Foundations written by Yoshiaki Kikuchi and has been published by Taylor & Francis this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-06-21 with Technology & Engineering categories.
Civil Engineering has recently seen enormous progress in the core field of the construction of deep foundations. This book is the result of the International Workshop on Recent Advances in Deep Foundations (IWDPF07), which was held in Yokosuka, Japan from the 1st to the 2nd of February, 2007. Topics under discussion in this book include recent rese
Development Of Recommended Resistance Factors For Drilled Shafts In Weak Rocks Based On O Cell Tests
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Author : Xiaoming Yang (Writer on geotechnical engineering)
language : en
Publisher:
Release Date : 2010
Development Of Recommended Resistance Factors For Drilled Shafts In Weak Rocks Based On O Cell Tests written by Xiaoming Yang (Writer on geotechnical engineering) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Load factor design categories.
From October 1, 2007, the new bridges on federal-aid funded projects are mandated to be designed to meet American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications. LRFD is a simplified form of reliability-based design. By multiplying calibrated factors to load and resistance components, the designed structure will maintain a specific level of reliability (or probability of failure). By concept, the load and resistance factors should be calibrated by large number of test data; however, they are often unavailable in geotechnical engineering. Significant efforts are needed to calibrate load and resistance factors based on test data of good quality. In this study, 26 O-Cell test data were collected from Kansas, Colorado, Missouri, Ohio, and Illinois. Seven methods available in the literature were selected to estimate the load capacities of 25 out of 26 drilled shafts. The "FHWA 0.05D" method was found to yield the closest and conservative predictions of the nominal resistances to the representative values; therefore, it was adopted in this study when calibrating the resistance factors for Strength Limit State design. These test data were analyzed and used to calibrate side and base resistance factors for drilled shafts in weak rock. Resistance factors were calibrated at two different target reliability indices: 2.3 (i.e., failure probability, Pf ~ 1/100) for shafts with greater redundancy and 3.0 (Pf ~ 1/1000) for shafts with less redundancy. Side resistance factors were calibrated from two different datasets of measured resistance: total side resistance and layered unit side resistance. The resistance factors calibrated from layered unit side resistance are considered more reliable, therefore, they are recommended for design. The recommended resistance factors from this study are compared with those in AASHTO specifications. Some of those calibrated resistance factors from this study are considerably lower than those in AASHTO specifications. The main reasons for such lower resistance factors are mainly attributed to the low efficiency of the FHWA design method and the limited quality and number of O-Cell test data. These resistance factors may be improved by increasing the size and the quality of the test data in the future. At present, field load tests on drilled shafts are recommended as an alternative to using lower resistance factors, which will also accumulate more test data for future improvement.
Drilled Shafts
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Author : National Highway Institute (U.S.)
language : en
Publisher:
Release Date : 1988
Drilled Shafts written by National Highway Institute (U.S.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Earthwork categories.
This document was written as a resource for participants in a short course covering the topic of construction and design of drilled shaft foundations for bridges and other structures. It is the second edition of a Federal Highway Administration workbook on construction and design of drilled shafts. The first edition was written in 1988 (FHWA-SA-HI-88-042). While introductory material from the 1988 edition was retained, the emphasis in this document is on providing relatively comprehensive information for engineers who already have some experience with drilled shaft construction and/or design. The initial chapters cover an overview of the characteristics of drilled shafts, site investigations for drilled shafts (to collect information for both construction and design), and details of drilled shaft construction. These chapters are followed by several chapters on the design of drilled shafts in soil and rock for both axial and lateral loading, with examples. Both allowable stress design and load and resistance factor design principles are addressed. Details of design calculations procedures are provided in the appendices.
Design Of Rock Socketed Drilled Shafts
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Author : Jamal Nusairat
language : en
Publisher:
Release Date : 2006
Design Of Rock Socketed Drilled Shafts written by Jamal Nusairat and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Bridges categories.
This project was aimed at evaluating and developing design methods for laterally loaded drilled shafts socketed in rock. Five lateral load tests on rock socketed drilled shafts with full range of instrumentation were conducted in Ohio. Detailed instrumentation included the use of vibrating wire strain gages, inclinometers, dial gages, and load cells. P-y curves representing site-specific lateral shaft-rock interaction were deduced from strain data. Field testing included the use of a borehole pressuremeter/dilatometer to obtain measurements that were correlated with rock mass strength and deformation parameters as well as with p-y curves. A comparison was made between the baseline p-y curves deduced from strain data of lateral load tests, the p-y curves predicted by using Reese's interim criterion, and the p-y curves from the pressuremeter tests in rock. A new hyperbolic p-y criterion for rock is proposed based on the field test data and extensive theoretical work. Validation of the proposed p-y criterion of rock was carried out by comparing the predictions of shaft deflections and bending moments using the hyperbolic p-y criterion against actual lateral load tests results. Based on the findings of this study, a complete solution for the design of drilled shafts socketed in rock or intermediate geomaterials under lateral loads is provided.
Study Of Side Shear Stress Development For Drilled Shafts In Very Weak Porous Limestone Using Axial Load Transfer Analyses
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Author : Matias R. Frediani
language : en
Publisher:
Release Date : 2023
Study Of Side Shear Stress Development For Drilled Shafts In Very Weak Porous Limestone Using Axial Load Transfer Analyses written by Matias R. Frediani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with Civil engineering categories.
This thesis presents a series of axial load transfer analyses performed to investigate the mobilization of side shear stresses of drilled shafts installed in a very weak, porous limestone formation in Puerto Rico (PR). The numerical analyses presented are predictions of two axial load tests carried out on instrumented drilled shafts installed in very weak, porous limestone at a test site located in northwest PR. The field test component was performed by a former MS student of the research group of Dr. Pando when employed by the University of Puerto Rico at MayaguÌ8ez. The test site involved an outcrop of a very weak, porous, and highly weathered limestone with a representative unconfined compressive strength (UCS) of 2.7 MPa, and an average rock quality designation (RQD) of 34%. Descriptions of the test site and the rock characterization are provided in this MS thesis. The main objective of this thesis was to investigate the mobilization of the side shear stresses of the two test drilled shafts installed in this unique very weak, porous limestone and assess whether load transfer analyses are suitable to predict the observed experimental behavior. The first focus of this study was to evaluate whether existing static methods could reasonably predict the measured ultimate side shear stresses, also referred to as unit shaft resistance. A total of 10 static methods were evaluate and the range of predictions of the unit shaft resistance was found to be very large, highlighting the need to improve our capability of predicting this important design parameter. Furthermore, the measured ultimate side shear stress values at the PR test site were found to be above the upper bound of the range of predicted values using the selected static methods. The higher measured unit shaft resistance values are attributed to limitation of the selected static methods that are solely based on only the intact rock UCS, and do not incorporate other important variables such as the surface roughness of the rock socket walls or stiffness ratio between drilled shaft and surrounding rock mass. The second focus of this MS thesis was to evaluate the ability to capture the axial load transfer mechanisms of the test drilled shafts and the experimental axial load versus settlement curves using load transfer analyses. The load transfer analyses behavior of the axial load tests was simulated using 1D finite element models of the deep foundation and springs using nonlinear T-Z curves to represent the development of the side shear stresses as a function of level of relative movement between the foundation and the rock. The literature review identified two T-Z curves formulations for very weak limestone. One formulation is from McVay and Niraula (2004) who proposed T-Z curves developed from centrifuge tests on simulated Florida limestone. The second formulation is a model developed by Asem and Gardoni (2019) based on a comprehensive database of drilled shaft load tests on very weak to weak rock. These two T-Z formulations were used to predict the experimental load-settlement curves. The predictions using the McVay and Niraula (2004) were much stiffer than the observed behavior. A modified T-Z formulation, based on the Asem and Gardoni (2019) was found to yield the best predictions and exhibit more flexibility because it depends not only on the unit shaft resistance but also on the stiffness or modulus of deformation of the rock mass. The modified load-transfer model was found to be reasonably adequate to predict the measured experimental behavior of the two test drilled shafts installed in the unique, very weak, porous limestone rock from the karst formation in northwest PR.
Drilled Shaft Design And Construction Guidelines Manual Construction Procedures And Design For Axial Loading
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Author : Lymon C. Reese
language : en
Publisher:
Release Date : 1977
Drilled Shaft Design And Construction Guidelines Manual Construction Procedures And Design For Axial Loading written by Lymon C. Reese and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Boring categories.
Drilled Shafts
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Author : Michael W. O'Neill
language : en
Publisher:
Release Date : 1999
Drilled Shafts written by Michael W. O'Neill and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Foundations categories.
Shaft98
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Author : Frank C. Townsend
language : en
Publisher:
Release Date : 1998
Shaft98 written by Frank C. Townsend and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Axial loads categories.