Showing papers by "Rodrigo Salgado published in 2004"

Two- and three-dimensional bearing capacity of foundations in clay

Abstract: Bearing capacity calculations are an important part of the design of foundations. Most of the terms in the bearing capacity equation, as it is used today in practice, are empirical. Shape factors for square and rectangular footings could not be derived in the past because three-dimensional bearing capacity computations could not be performed with any degree of accuracy. Likewise, depth factors could not be determined because rigorous analyses of foundations embedded in the ground were not available. In this paper, the bearing capacities of strip, square, circular and rectangular foundations in clay are determined rigorously based on finite element limit analysis. The results of the analyses are used to propose rigorous, definitive values of the shape and depth factors for foundations in clays. These results are helpful in reducing the uncertainties related to the method of analysis in bearing capacity calculations, paving the way for more cost-effective foundation design.

Measurement of pile load transfer using the Fiber Bragg Grating sensor system

Abstract: A series of laboratory and field tests were performed to evaluate the applicability of an optical fiber sensor system in the instrumentation of piles. A multiplexed sensor system, constructed by ar...

Stiffness degradation and shear strength of silty sands

Abstract: Soils behave nonlinearly from very early loading stages. When granular soils contain a certain amount of fines, the degree of nonlinearity also changes, as stiffness and strength characteristics va...

Effect of Pile Installation Method on Pipe Pile Behavior in Sands

Abstract: Open-ended pipe piles are often used for the foundations of both land and offshore structures because of their relatively low driving resistance. In this study, calibration chamber tests were conducted on model pipe piles installed in sands with different soil conditions in order to investigate the effects of the pile installation method on penetration parameters and bearing capacity. Results of the test program showed that both the hammer blow count necessary to install the piles and the incremental filling ratio (IFR), which is used to indicate the degree of soil plugging in open-ended piles, decreased (1) with increasing hammer weight for the same driving energy, and (2) with increasing hammer weight at the same fall height. The base and shaft load capacities of the piles were observed to increase (1) with increasing hammer weight for the same driving energy, and (2) with increasing hammer weight for the same fall height. It was also observed that the noise level observed during pile driving decreases (1) as the driving energy decreases and (2) as the hammer weight increases for the same driving energy. Model jacked piles were also installed and tested. The jacked piles were found to have higher bearing capacities than identical driven piles under similar conditions, mostly due to the more effective development of soil plugging in jacking than in driving.

Use of recycled and waste materials in indiana

Abstract: The improved generation, handling, and safe disposal of waste and recycled materials have become a major concern in the United States. Generators of waste are under growing pressure either to find new facilities to dispose of it, as old facilities reach their capacity, or to recycle the waste. In addition to a scarcity of disposal facilities and the associated escalating costs, stringent regulations and public perceptions have caused local governments to seek ways to use waste materials in a productive way. The Indiana Department of Transportation has been proactive and has initiated and funded several research projects in cooperation with generators to determine safe and beneficial uses in road construction. Efforts are still under way to find economically feasible and environmentally sound geotechnical applications of waste and recycled materials. This study consolidates results of research on geotechnical applications of coal combustion by-products, foundry sand, tire shreds, and crushed glass. Project case histories and revised construction specifications based on postconstruction evaluations are also presented. These geotechnical applications suggest that significant cost savings can be attained, in addition to the positive environmental impact, with the use of these materials.

Limit States Design (LSD) for Shallow and Deep Foundations

Abstract: Load and Resistance Factor Design (LRFD) shows promise as a viable alternative to the present working stress design (WSD) approach to foundation design. The key improvements of LRFD over the traditional Working Stress Design (WSD) are the ability to provide a more consistent level of reliability and the possibility of accounting for load and resistance uncertainties separately. In order for foundation design to be consistent with current structural design practice, the use of the same loads, load factors and load combinations would be required. In this study, the authors review the load factors presented in various LRFD Codes from the US, Canada and Europe. A simple firstorder second moment (FOSM) reliability analysis is presented to determine appropriate ranges for the values of the load factors. These values are compared with those proposed in the Codes. The comparisons between the analysis and the Codes show that the values of load factors given in the Codes generally fall within ranges consistent with the results of the FOSM analysis. For LRFD to gain acceptance in geotechnical engineering, a framework for the objective assessment of resistance factors is needed. Such a framework, based on reliability analysis is proposed in this study. Probability Density Functions (PDFs), representing design variable uncertainties, are required for analysis. A systematic approach to the selection of PDFs is presented. Such a procedure is a critical prerequisite to a rational probabilistic analysis in the development of LRFD methods in geotechnical engineering. Additionally, in order for LRFD to fulfill its promise for designs with more consistent reliability, the methods used to execute a design must be consistent with the methods assumed in the development of the LRFD factors. In this study, a methodology for the estimation of soil parameters for use in design equations is proposed that should allow for more statistical consistency in design inputs than is possible in traditional methods. Resistance factor values are dependent upon the values of load factors used. Thus, a method to adjust the resistance factors to account for code-specified load factors is also presented. Resistance factors for ultimate bearing capacity are computed using reliability analysis for shallow and deep foundations both in sand and in clay, for use with both ASCE-7 (1996) and AASHTO (1998) load factors. The various considered methods obtain their input parameters from the CPT, the SPT, or laboratory testing. Designers may wish to use design methods that are not considered in this study. As such, the designer needs the capability to select resistance factors that reflect the uncertainty of the design method chosen. A methodology is proposed in this study to accomplish this task, in a way that is consistent with the framework.

Mechanical behavior of non-textbook soils

Abstract: The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Indiana Department of Transportation or the Federal Highway Administration. This report does not constitute a standard, specification or regulation. Traditionally, soil mechanics has focused on the behavior of two distinct types of geomaterials: clean sands and pure clays. Under the application of external loads, these two types of geomaterials represent and are conveniently associated with two extreme types of soil responses: drained and undrained behavior. The drained behavior of clean sands and the undrained behavior of pure clays have been covered extensively in most soil mechanics textbooks. In order to provide some insight into the mechanical response of additional materials, a literature review on the mechanical behavior of " non-textbook " soils (i.e. soils other than clean sands and pure clays) was carried out. The non-textbook soils investigated in this study were silty sands, clayey sands, silty clays, sandy clays, sandy silts, and cemented soils. The review focused on the following aspects of their mechanical behavior: (1) response to static loading; (2) response to cyclic loading; (3) compressibility, consolidation and creep behavior; (4) hydraulic conductivity; and (5) additional studies. Static response studies focused on both strength and stiffness properties of non-textbook soils. Investigations on the cyclic response emphasized the liquefaction resistance and, whenever available, the evolution of excess pore-pressure during cyclic loading. Whenever possible, an attempt was made to compile experimental protocols and theoretical frameworks used in the studies cited in the literature review. The literature review indicates that many aspects of the mechanical behavior of non-textbook soils have been studied in a somewhat superficial manner. A summary of the major observations regarding the mechanical behavior of non-textbook soils is presented. Topics meriting future research are identified. Introduction Traditionally, soil mechanics has focused on the behavior of two distinct types of geomaterials: clean sands and pure clays. Under the application of external loads, these two types of geomaterials represent and are conveniently associated with two extreme types of soil responses: drained and undrained behavior. The drained behavior of clean sands and the undrained behavior of pure clays have been covered extensively in most soil mechanics textbooks. In order to provide some insight into the mechanical response of additional materials, a literature review …

Mechanical behavior of non-textbook soils. literature review

Abstract: Traditionally, soil mechanics has focused on the behavior of two distinct types of geomaterials: clean sands and pure clays. Under the application of external loads, these two types of geomaterials represent and are conveniently associated with two extreme types of soil responses: drained and undrained behavior. The drained behavior of clean sands and the undrained behavior of pure clays have been covered extensively in most soil mechanics textbooks. In order to provide some insight into the mechanical response of additional materials, a literature review on the mechanical behavior of "non-textbook" soils (i.e., soils other than clean sands and pure clays) was carried out. The non-textbook soils investigated in the study were silty sands, clayey sands, silty clays, sandy clays, sandy silts and cemented soils. The review focused on the following aspects of their mechanical behavior: (1) response to static loading; (2) response to cyclic loading; (3) compressibility, consolidation and creep behavior; (4) hydraulic conductivity; and (5) additional studies. Static response studies focused on both strength and stiffness properties of non-textbook soils. Investigations on the cyclic response emphasized the liquefaction resistance and, whenever available, the evolution of excess pore-pressure during cyclic loading. Whenever possible, an attempt was made to compile experimental protocols and theoretical frameworks used in the studies cited in the literature review. The literature review indicates that many aspects of the mechanical behavior of non-textbook soils have been studied in a somewhat superficial manner. A summary of the major observations regarding the mechanical behavior of non-textbook soils is presented. Topics meriting future research are identified.

Briefing: construction of tyre-shreds test embankment

Abstract: In view of the vast numbers of used tyres stockpiled across the USA and their problematic disposal characteristics, it makes environmental and financial sense to find ways of recycling them. This briefing paper describes a research project which was undertaken in Indiana to construct and test a soil-tyre embankment. Findings are outlined and recommendations made. (A)