David J. Kerkes, Ph.D., P.E.

Consulting Geotechnical (Civil) Engineer

Articles, Abstracts & Design Tools

Copyrighted material is available at this web site with the permission of the copyright holders.

Below is a list of articles and papers that may be of interest to my colleagues in civil and geotechnical engineering. The documents are in Adobe Acrobat (PDF) 5.0 Format; therefore, the Adobe Acrobat reader will be needed to view the articles, a free copy of which can be downloaded from the Adobe web site at www.adobe.com

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Kerkes, D. J., "Precepts of Project Management," ASCE Civil Engineering magazine, September 1994, pp 70-72

The paper is presented here with the permission of The American Society of Civil Engineers (ASCE). To view a list of publications and abstracts available through ASCE, visit their web site at  www.pubs.asce.org

Filename:    proj-mgt.pdf          Filesize:    146,102 bytes          4 pages

ABSTRACT:  Successful projects share at least two characteristics:   They are completed on schedule and within budget. Achieving these goals is the quintessential measure of good project management. Most engineers realize this, but lack an understanding of the skills and procedures necessary to achieve these objectives, since engineers are generally not schooled in the basics of project management. An engineer's formal education is almost exclusively focused on the technical aspects of the profession. Engineering colleges have traditionally assumed that their graduates would acquire project management skills on the job. Consequently, engineers typically learn it (or not) from their role models, who generally are the senior engineers with whom they work, some of whom are poor project managers themselves. This article provides some pointers, based on personal observations and experience, that could make project managers more effective.

Kerkes, D. J., "Why Engineers Get Sued And How To Reduce Your Risk," Proceedings of the ASCE Texas Section Spring Meeting, Beaumont, TX, 19-22 April 2006

Filename:    lawsuits.pdf          Filesize:    107,148 bytes          5 pages

ABSTRACT:  It seems that increasingly we are learning about failures in civil engineering structures, which were once rare, and these are only the ones that make the news. With what seems like ever increasing pressure to be cost competitive, engineering firms are implementing practices that place themselves at risk for litigation, often without realizing the potential consequences. As a consultant who has provided his services as an expert on a number of cases and has conferred with professional associates on others, the author provides some observations on a few of the common reasons that engineers get sued in the hope of helping firms identify and eliminate areas of risk.

Kerkes, D. J., & Fassett, J. B., "Rapid Drawdown In Drainage Channels With Earthen Side Slopes," Proceedings of the ASCE Texas Section Spring Meeting, Beaumont, TX, 19-22 April 2006

Filename:    drawdown.pdf          Filesize:    221,197 bytes          9 pages including 5 figures

ABSTRACT:  The rapid drawdown case is one of the most severe loading conditions that an earthen slope can experience and is quite common in storm water drainage channels along the Texas Gulf Coast. Flooding in adjacent rivers can leave water levels high in these drainage channels, which can drop relatively rapidly once floodwaters recede. While the development of deep seated failure surfaces is possible, the effect on earthen side slopes is most commonly seen in the form of relatively shallow slope failures, which if left unattended lead to the gradual deterioration of the channel slopes. Though the information presented in this paper is generally applicable to any earthen side slopes, of particular interest are slopes consisting of overconsolidated clays where it is not uncommon for slope failures to occur long after a channel has been constructed. This paper discusses a number of the factors associated with this loading condition, as well as some of the design issues, and presents the results of a series of finite element seepage analyses that were performed to investigate the effect of some of the variables on the advance of the zone of saturation into the channel side slope.

Kerkes, D. J., "Analysis of Equipment Loads on Geocomposite Liner Systems," Proceedings of the Geosynthetics '99 Conference, IFAI, Boston, MA, April 1999, pp 1043-1054

The paper is presented here with the permission of The Industrial Fabrics Association International (IFAI).

Filename:    geosyn99.pdf          Filesize:    288,177 bytes          11 pages including 9 figures

ABSTRACT:   The loads imposed on geosynthetics during installation are frequently the most severe that the materials will experience during their service life; however, they are among the most difficult to evaluate. This paper examines the loads imposed by track mounted and rubber tired vehicles spreading soil over the liner system during construction and proposes an analysis that uses three-dimensional sliding blocks for computing a factor of safety for the liner system under such loads, which takes into account the effect of the soil cover between the equipment and potential failure surface, as well as the effect of tensile forces in components of the liner above that surface. The solution algorithm, which is presented in some detail, can be executed using standard spreadsheet software. The limitations of the method are also discussed, and suggestions are made for using the method in light of the complex stress-strain behavior of composite liner systems.

EXAMPLE SPREADSHEET:   As a companion to the paper, and at no cost, an example spreadsheet (in Microsoft Excel format) can be downloaded to illustrate a solution for the case of a bulldozer traveling in the upslope direction while spreading cover soil over the liner system. While considerable effort has been spent to ensure that the spreadsheet is free of errors, the author does not warrant that the spreadsheet is error free. The decision to place any reliance on the method presented in the paper and illustrated in the companion spreadsheet, as well as any conclusions drawn from the results, are ultimately the responsibility of the designer.

Filename:    bulldozr.xls          Filesize:    44,032 bytes

Kerkes, D. J., "Factors To Consider When Planning Landfill Construction," Proceedings of the Eighth Annual Texas Municipal Solid Waste Management Conference, January 1995, Austin, TX, pp 115-122

The paper is presented here with the permission of The Texas Natural Resource Conservation Commission (TNRCC).

Filename:    landfill.pdf          Filesize:    169,742 bytes          8 pages including 1 figure

ABSTRACT:   The complexity of composite liner systems required to meet Subtitle D regulations and the difficulties inherent in constructing the liner systems have definite implications on the time necessary to complete construction. When planning the construction or expansion of a landfill the failure to properly consider the various factors involved in actual construction can have serious consequences in terms of project delays and additional costs. For many landfills the loss of air space is the ultimate cost of missing a construction completion date.   This paper offers some practical suggestions, based on actual construction experience, to assist owners in developing realistic construction schedules. The paper is intended to make the reader aware of certain aspects that frequently seem to be ignored and to alert owners to potential problems, as well as possible courses of action to avert problems. The points outlined in the paper will also assist owners in evaluating the qualifications of potential contractors who may propose on landfill construction projects.

Kerkes, D. J., "The Engineering Proposal as a Tool for Teaching Integrated Design," Proceedings of the ASEE Gulf-Southwest Conference, March 23-25, 1997, pp 338-343

The paper is presented here with the permission of the American Society for Engineering Education (ASEE).

Filename:    int-dsgn.pdf          Filesize:    141,840 bytes          7 pages

ABSTRACT:   Integrated design and/or capstone design courses seem to present a number of challenges to both faculty and students. The need for the instructor to be able to evaluate student design work outside his/her area of expertise tends to make some faculty members uncomfortable teaching such courses. The lack of well defined problems and the open ended nature of engineering design, coupled with their lack of practical experience, tends to frustrate many students in such courses. In addition, our colleagues in business and industry have definite ideas as to what should be included in an integrated design or capstone design course, and these ideas are not always well received by engineering faculty members. What is not always apparent, however, is the fact that business and industry can be an invaluable resource that can enhance the education experience for both the students and the instructor. This paper endeavors to identify some of the challenges and difficulties that seem to be common to integrated design courses and discusses how they can be met through the use of the engineering proposal as an instrument for teaching integrated design.

Kerkes, D. J., "A Simple Model For Estimating End Of Construction Pore Pressures: Part 1 - Foundation Pore Pressures," copyright 2001 by David J. Kerkes

Filename:    eocpapr1.pdf          Filesize:    322,494 bytes          19 pages including 6 figures

Kerkes, D. J., "A Simple Model For Estimating End Of Construction Pore Pressures: Part 2 - Embankment Pore Pressures," copyright 2004 by David J. Kerkes

Filename:    eocpapr2.pdf          Filesize:    351,465 bytes          21 pages including 5 figures

ABSTRACT:   These are application oriented papers intended specifically for design engineers looking for practical, cost effective methods to address the problem of estimating construction generated pore pressures. The papers, both of which are available over the Internet at no cost, present the details of analytical models for estimating both the magnitude and rate of dissipation of construction generated excess pore pressures.

The problem of estimating construction generated excess pore pressures in soil can be thought of in terms of three interdependent components. The first involves establishing the stresses applied to the soil. The second involves defining the pore pressure response of the soil to the stress changes that occur as the load is applied. The third is the consolidation process, which addresses the dissipation of excess pore pressures during construction. The primary components of the model consist of: a) an approximate method for estimating the stresses beneath the loaded area, b) a method for computing the pore pressures generated in the foundation or embankment, and c) a two-dimensional finite difference consolidation algorithm to account for pore pressure dissipation during construction.

The method was originally developed by the author to analyze the problem of excess pore pressure development within the core zone of an earth and rockfill dam during construction, where both the distribution of stresses and dissipation of pore pressures are essentially two-dimensional. The method was specifically developed to permit the analyses to be performed on a personal computer using commercially available spreadsheet software, thereby eliminating the need for special application software. An abstract of the author's doctoral dissertation, in which the method was first presented, is provided below. While the method has previously been presented by the author in published form, these papers have been developed and presented here, with companion spreadsheets, because most of us find it difficult to implement a new method without information that frequently does not survive the editorial process for papers that appear in journals and conference proceedings. The purpose of the papers is to provide what is hoped will be a sufficient amount of detail for an engineer to apply the method to his/her specific problem. As a companion to each paper, a spreadsheet has been prepared by the author, in Microsoft Excel (97-2000 & 5.0/95 compatible formats), illustrating the solution to the example problem presented in the paper.

For the purpose of illustrating the basic method the first paper is limited to the case of a fully saturated soft soil foundation over which an earth structure is constructed. The author recommends this paper as the best place to begin for those individuals who may not be familiar with the various elements of this complex problem. Since the method is capable of modeling the actual embankment construction, the first paper includes a simple procedure for estimating the rate of load application, which equates to the project construction schedule. The second paper discusses how the model can be extended to account for an unsaturated soil, as well as the case of a moving drainage boundary, and illustrates how to estimate construction generated pore pressures within the core of a zoned earth dam.

EXAMPLE SPREADSHEETS:   As a companion to each paper, and at no cost, example spreadhseets (in Microsoft Excel format) can be downloaded to illustrate the procedure for estimating the construction pore pressures in a saturated foundation over which an earth structure is constructed (Example Problem 1), and for estimating the construction pore pressures in the unsaturated core of a zoned earth dam at any time during construction (Example Problem 2). While considerable effort has been spent to ensure that the spreadsheets are free of errors, the author does not warrant that the spreadsheets are error free. The decision to place any reliance on the methods presented in the papers and illustrated in the companion spreadsheets, as well as any conclusions drawn from the results, are ultimately the responsibility of the designer.

Filename:    ex-prob1.xls          Filesize:    343,552 bytes

Filename:    ex-prob2.xls          Filesize:    373,760 bytes

Kerkes, D. J., "Analysis and Prediction of Stresses and Pore Pressures Associated with Wet Core Construction for Embankment Dams," a thesis submitted to the faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy, May 1990

ABSTRACT:   The wet core construction method has been successfully applied to embankment dams in parts of the world that experience high annual rainfall, where the natural moisture content of core zone construction material is so far above optimum as to render fill placement to conventionally accepted standards infeasible. While the method has definite advantages in terms of construction cost and schedule, a significant disadvantage is associated with the high pore pressures that develop during construction. This study examines the factors governing pore pressure generation, as well as those affecting the distribution of stresses within the embankment. The primary purpose of the investigation was to develop a simple analytical model that could be used for routine design purposes to estimate the pore pressures that develop during construction in the core of a zoned embankment. Field data from a 394 feet (120 meter) high wet core dam constructed in Indonesia was used to validate the model. The secondary objective was to study the instrumentation data obtained from total stress cells, piezometers and settlement devices, in an effort to better understand the internal stress distribution, pore pressures and consolidation that occur in a zoned embankment with a wet core.

The investigation yielded a relatively straightforward analytical model for estimating pore pressures in the core of a zoned embankment that can be executed using a desk top personal computer and commercially available spreadsheet software. The primary components of the model consist of (1) an approximate method for estimating the stresses within the core, (2) an algorithm for computing the pore pressures generated in the core, which considers the effect of partial saturation, and (3) a two-dimensional finite difference solution for the uncoupled multi-dimensional consolidation theory of Terzaghi-Rendulic to account for pore pressure dissipation during construction. The model can be adapted to virtually any core zone geometry, simulates the advancing fill by providing for a moving upper boundary that can be controlled to approximate the actual construction sequence, and permits pore pressures along the upstream boundary to be varied to model reservoir impoundment. The solution algorithms for the model are presented in detail.

The dissertation itself is not available at this web site; however, individuals that may be interested in the work can download a copy of the abstract and table of contents here, which includes a figure illustrating the location of instruments in the core zone, as well as a comparison of the results obtained using the model to actual field data collected during construction. The dissertation also presents (in tabular form) field data obtained during construction from total stress cells and piezometers in the core zone, as well as settlement data, for a 394 feet (120 meter) high zoned earth and rockfill dam constructed in Southeast Asia using the wet core construction method.

Filename:    phd-toc.pdf          Filesize:    175,910 bytes          7 pages including 3 figures

A copy of the dissertation can be obtained from UMI (University Microfilms Inc.) Dissertation Services, Ann Arbor, Michigan, USA. Their web site is www.umi.com, and online dissertation services are provided by "Dissertation Express" at tls.il.proquest.com/hp/Products/DisExpress.html

This information is presented here as a professional courtesy. The author does not receive any compensation from either UMI Dissertation Services or Dissertation Express should an individual decide to place an order.

David J. Kerkes, Ph.D., P.E.
Consulting Geotechnical Engineer
1311 Mustang Trail
Kingwood, Texas 77339   U.S.A.

281-358-5155             dkerkes@earthlink.net