SOIL CHARACTERIZATION AND P-Y CURVE DEVELOPMENT FOR LOESS

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SOIL CHARACTERIZATION AND P-Y CURVE DEVELOPMENTFOR LOESS

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  • Report No. K-TRAN: KU-05-3 FINAL REPORT SOIL CHARACTERIZATION AND P-Y CURVE DEVELOPMENT FOR LOESS Rebecca Johnson Robert L. Parsons The University of Kansas Steven Dapp Dan Brown Dan Brown and Associates

    FEBRUARY 2007 K-TRAN A COOPERATIVE TRANSPORTATION RESEARCH PROGRAM BETWEEN: KANSAS DEPARTMENT OF TRANSPORTATION KANSAS STATE UNIVERSITY THE UNIVERSITY OF KANSAS

  • 1 Report No. K-TRAN: KU-05-3

    2 Government Accession No.

    3 Recipient Catalog No.

    5 Report Date February 2007

    4 Title and Subtitle SOIL CHARACTERIZATION AND P-Y CURVE DEVELOPMENT FOR LOESS

    6 Performing Organization Code

    7 Author(s) Rebecca Johnson & Robert L. Parsons, both with University of Kansas, and Steven Dapp and Dan Brown, both with Dan Brown and Associates

    8 Performing Organization Report No.

    10 Work Unit No. (TRAIS)

    9 Performing Organization Name and Address University of Kansas Civil, Environmental & Architectural Engineering Department 1530 West 15th Street Lawrence, Kansas 66045-7609

    11 Contract or Grant No. C1483

    13 Type of Report and Period Covered Final Report July 2004 July 2006

    12 Sponsoring Agency Name and Address Kansas Department of Transportation Bureau of Materials and Research 700 SW Harrison Street Topeka, Kansas 66603-3754

    14 Sponsoring Agency Code RE-0376-01

    15 Supplementary Notes For more information write to address in block 9.

    16 Abstract Lateral loads on drilled shafts are often the controlling factor in their design. These lateral loads are transferred to

    the surrounding soil or rock, and estimation of the capacity of the shaft to resist lateral loads is a critical part of the design. The lateral load-deformation relationship of a drilled shaft and its supporting soil is commonly modeled using the p-y curve method. P-y curves vary with soil type, deposition characteristics and depth, but general curves have been developed to represent common soils. Unfortunately, no p-y curves have been developed to represent the behavior of loess, cemented silt that is common throughout much of Kansas. This lack of available p-y relationships has meant that less applicable curves, normally those for sandy soils, must be used.

    The purpose of this research was to define the significant engineering properties of Kansas loessal soils through a literature review, laboratory tests, and in situ tests and to determine the soil-structure response by performing full scale lateral load tests on six drilled shafts.

    Laboratory testing included saturated and unsaturated triaxial, direct shear, consolidation and collapse testing. Field tests included SPT, CPT, vane shear, and pressuremeter testing. Two pairs of shafts with diameters of 30 and 42 inches were tested under static loading. A third pair of 30 inch shafts was tested under repeated loading. Shaft deflections were measured using inclinometer soundings and correlated with the CPT cone tip resistance (qc). A hyperbolic model was developed to correlate ultimate soil resistance (Puo) to the CPT cone tip resistance (qc) for both static and repeated loading at any given depth and was used to develop a family of p-y curves unique to loess.

    This model may be entered into the commercially available software package LPILE for design of laterally loaded drilled shafts constructed in loess.

    17 Key Words Drilled Shafts, In Situ Testing, Loess, P-Y Curves, Soil and Triaxial Testing.

    18 Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161

    19 Security Classification (of this report)

    Unclassified

    20 Security Classification (of this page) Unclassified

    21 No. of pages 199

    22 Price

    Form DOT F 1700.7 (8-72)

  • SOIL CHARACTERIZATION AND P-Y CURVE

    DEVELOPMENT FOR LOESS

    Final Report

    Prepared by

    Rebecca Johnson Robert L. Parsons

    The University of Kansas

    Steven Dapp Dan Brown

    Dan Brown and Associates

    A Report on Research Sponsored By

    THE KANSAS DEPARTMENT OF TRANSPORTATION TOPEKA, KANSAS

    and

    UNIVERSITY OF KANSAS CENTER FOR RESEARCH, INC.

    LAWRENCE, KANSAS

    February 2007

    Copyright 2007, Kansas Department of Transportation

  • ii

    PREFACE The Kansas Department of Transportations (KDOT) Kansas Transportation Research and New-Developments (K-TRAN) Research Program funded this research project. It is an ongoing, cooperative and comprehensive research program addressing transportation needs of the state of Kansas utilizing academic and research resources from KDOT, Kansas State University and the University of Kansas. Transportation professionals in KDOT and the universities jointly develop the projects included in the research program.

    NOTICE The authors and the state of Kansas do not endorse products or manufacturers. Trade and manufacturers names appear herein solely because they are considered essential to the object of this report. This information is available in alternative accessible formats. To obtain an alternative format, contact the Office of Transportation Information, Kansas Department of Transportation, 700 SW Harrison, Topeka, Kansas 66603-3754 or phone (785) 296-3585 (Voice) (TDD).

    DISCLAIMER The contents of this report reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the views or the policies of the state of Kansas. This report does not constitute a standard, specification or regulation.

  • iii

    Abstract

    Lateral loads on drilled shafts are often the controlling factor in their design. These

    lateral loads are transferred to the surrounding soil or rock, and estimation of the

    capacity of the shaft to resist lateral loads is a critical part of the design. The lateral

    load-deformation relationship of a drilled shaft and its supporting soil is commonly

    modeled using the p-y curve method. P-y curves vary with soil type, deposition

    characteristics and depth, but general curves have been developed to represent

    common soils. Unfortunately, no p-y curves have been developed to represent the

    behavior of loess, cemented silt that is common throughout much of Kansas. This lack

    of available p-y relationships has meant that less applicable curves, normally those for

    sandy soils, must be used.

    The purpose of this research was to define the significant engineering properties

    of Kansas loessal soils through a literature review, laboratory tests, and in situ tests

    and to determine the soil-structure response by performing full scale lateral load tests

    on six drilled shafts.

    Laboratory testing included saturated and unsaturated triaxial, direct shear,

    consolidation and collapse testing. Field tests included SPT, CPT, vane shear, and

    pressuremeter testing. Two pairs of shafts with diameters of 30 and 42 inches were

    tested under static loading. A third pair of 30 inch shafts was tested under repeated

    loading. Shaft deflections were measured using inclinometer soundings and correlated

    with the CPT cone tip resistance (qc). A hyperbolic model was developed to correlate

    ultimate soil resistance (Puo) to the CPT cone tip resistance (qc) for both static and

  • iv

    repeated loading at any given depth and was used to develop a family of p-y curves

    unique to loess.

    This model may be entered into the commercially available software package

    LPILE for design of laterally loaded drilled shafts constructed in loess.

    Acknowledgements

    The authors wish to acknowledge the financial and logistical support of the Kansas

    Department of Transportation and James Brennan and the people of the Materials and

    Research Geotechnical Unit in particular. Their assistance in drilling, sampling, testing

    and data processing were essential for the preparation of this report. The authors also

    wish to acknowledge the substantial contributions of Mike Hayes, Luke Schuler, and the

    people of Hayes Drilling, who volunteered to construct the shafts for the benefit of this

    research. The contributions of all involved are greatly appreciated.

  • v

    Table of Contents

    ABSTRACT...............................................................................................................III

    ACKNOWLEDGEMENTS ..................................................................................... IV

    TABLE OF CONTENTS ...........................................................................................V

    CHAPTER 1.................................................................................................................1

    INTRODUCTION........................................................................................................1

    CHAPTER 2.................................................................................................................4

    LITERATURE REVIEW ...........................................................................................4 2.1 LOESS ................................................................................................................................ 4

    2.1.1 Origin...................................................................................................................... 4 2.1.2 Geotechnical Characteristics.................................................................................. 7