Download or read book Side Resistance of Drilled Shafts in Weak Rock written by Eric W. Sandberg and published by . This book was released on 1993 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 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 published by . This book was released on 2010 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Drilled Shafts written by Michael W. O'Neill and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Load and Resistance Factor Design of Drilled Shafts in Shale Using Standard Penetration Test and Texas Cone Penetration Test Measurements written by Mark Daniel Pierce and published by . This book was released on 2013 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Missouri Department of Transportation (MoDOT) designers currently follow American Association of State Highway and Transportation Officials (AASHTO) design methods for design of drilled shafts in shale and other weak rock. These methods are generally based on Load and Resistance Factor Design (LRFD) methods that relate uniaxial compressive strength measurements of rock cores to the side and tip resistance for drilled shafts. However, shale and other weak rock can be notoriously difficult to effectively sample and test, which poses practical problems for those tasked with designing drilled shafts in such materials. The difficulty in sampling shale has lead geotechnical engineers to consider in-situ tests, such as the Standard Penetration Test (SPT) and the Texas Cone Penetration test (TCP), as surrogates for conventional coring and laboratory testing. In order to utilize results of in-situ tests for design of drilled shafts using Load and Resistance Factor Design (LRFD), it is necessary to correlate in-situ test measurements with side and tip resistance and to establish calibrated resistance factors that account for the reliability of the correlations and the in-situ test measurements. This thesis describes efforts undertaken to develop improved correlations among in-situ test measurements and drilled shaft capacity and to develop resistance factors that produce established target reliabilities for different classes of roadways.

Download or read book Drilled Shaft Design and Construction Guidelines Manual written by Lymon C. Reese and published by . This book was released on 1977 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Drilled Shafts in Rock written by Lianyang Zhang and published by CRC Press. This book was released on 2004-05-15 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drilled shafts in rock are widely used as foundations of heavy structures such as highway bridges and tall buildings. Although much has been learned about the analysis and design of drilled shafts in rock, all the major findings are published in the form of reports and articles in technical journals and conference proceedings. This book i

Download or read book Drilled Shaft Design and Construction Guidelines Manual Construction procedures and design for axial loading written by Lymon C. Reese and published by . This book was released on 1977 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rock socketed Shafts for Highway Structure Foundations written by John P. Turner and published by Transportation Research Board. This book was released on 2006 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Drilled Shafts written by National Highway Institute (U.S.) and published by . This book was released on 1988 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Base Resistance of Drilled Shafts in Rock written by Stetson B. Ramey and published by . This book was released on 2009 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method is presented to calculate the nominal base resistance of a drilled shaft socketed into a fractured rock mass by using the Hoek-Brown strength criterion and its input parameter the Geological Strength Index (GSI). Base resistance is sometimes neglected when designing drilled shafts embedded in fractured rock masses resulting in large diameter shafts because the entire load is designed to be resisted through side shear. While a fractured rock mass will not have as much bearing capacity as an intact rock mass, usually even a fractured rock mass is able to resist a significant portion of the applied load. Data from load tests on drilled shafts embedded into various types of rock are compared to the theoretical relationship between the GSI and nominal base resistance. The data were all from sources where the drilled shaft was loaded to failure in end bearing and the nominal bearing resistance had been determined. The sources also include necessary rock mass properties. One case was analyzed with the intent of comparing the actual load test data against the theoretical relationship proposed, so rock core boring was taken with the intent of determining a value for the GSI. This data point matches up extremely well with the theoretical relationship. For the other thirteen data points, a value of GSI was estimated from detailed descriptions of the rock mass found in the geotechnical report and boring logs or GSI was correlated to another rock mass rating system. In these cases, the theoretical relationship appears to yield a lower bound to rock socket base resistance. By comparing actual data to the theoretical relationship presented in this thesis, it is determined that the method is a useful tool to estimate the bearing capacity of a rock mass.

Download or read book 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 published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Pile Design and Construction Practice written by Willis H. Thomas and published by CRC Press. This book was released on 2007-12-06 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: This international handbook is essential for geotechnical engineers and engineering geologists responsible for designing and constructing piled foundations. It explains general principles and practice and details current types of pile, piling equipment and methods. It includes calculations of the resistance of piles to compressive loads, pile group

Download or read book Introduction to Rock Mechanics written by Richard E. Goodman and published by John Wiley & Sons. This book was released on 1991-01-16 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduces a new approach to rock mechanics called ``block theory,'' which formalizes procedures for selecting proper shapes and orientations for excavations in hard jointed rock. Applies block theory to rock slopes and underground excavations, and covers the Q theory of rock classification, the empirical criterion of joint shear strength, rock bolting, properties of weak rocks, statistical frequency of jointing, an empirical criterion of rock strength, and design of underground supports. Contains many new problems with worked-out solutions.

Download or read book Improvement of the Geotechnical Axial Design Methodology for Colorado s Drilled Shafts Socketed in Weak Rocks written by Naser Abu-Hejleh and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Drilled Shaft Design and Construction Guidelines Manual Reese L C and Allen J D Structural analysis and design for lateral loading written by Lymon C. Reese and published by . This book was released on 1977 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Improved Design Economy for Drilled Shafts in Rock written by and published by . This book was released on 2002 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Contemporary Topics in Deep Foundations written by Magued Iskander and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: GSP 185 contains 80 papers presented at the International Foundation Congress and Equipment Expo held in Orlando, Florida, March 15-19, 2009.