00715545

Component

http://onlinepubs.trb.org...trr/1995/1504/1504-008.pdf

https://scholar.google.co...rian&publication_year=1995

Resilient moduli of subgrades are becoming important input parameters in mechanistic pavement design. As such, test methodologies have been introduced by many highway agencies to estimate this parameter. These tests require several hours to perform. Therefore, only a small number of specimens can be tested for a given project. An alternative for rapidly determining the resilient modulus of subgrade soils--bender elements--is presented. Bender elements are thin sheets of piezo-ceramic material which are inserted in a specimen. When subjected to appropriate electric current, a bender element bends and couples seismic energy to the specimen. A bender element can also be used to detect the coupled energy since it converts movement to voltage. For convenience, the end caps of a regular static triaxial test set-up can be retrofitted with a set of transmitting and receiving bender elements. The data reduction, which consists of determining the arrival time of the seismic energy, is simple and can be carried out during the test. The limitation of the device is that the deviatoric stress cannot be varied and as such moduli at low strain levels are measured. Therefore, this method can be utilized parallel to resilient modulus tests when a large number of specimens of similar subgrades must be tested. Based on tests on over 30 different specimens, the bender elements can feasibly provide resilient moduli of subgrade materials at a fraction of the time and at significantly lower investment in initial equipment costs. The bender element tests can be a complement to the resilient modulus test systems.

This paper appears in Transportation Research Record No. 1504, Modeling and Model Verification; Testing Pavement Layers and Materials; and Low-Cost Drainage Structures. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01399829

English

p. 79-86

1995

Transportation Research Record

0309061725

Figures (7) ; References (12) ; Tables (2)

Cost effectiveness; Modulus of resilience; Productivity; Subgrade (Pavements)

Bender elements; Rapid methods; Time savings

Design; Highways; Pavements; I22: Design of Pavements, Railways and Guideways

TRIS, TRB

Jan 2 1996 12:00AM

• CENTRIFUGAL MODELING OF LEAKING UNDERGROUND STORAGE TANKS
• DETERMINATION OF DEPTH TO BEDROCK FROM FALLING WEIGHT DEFLECTOMETER TEST DATA
• ESTIMATING PERMEABILITY OF ASPHALT-TREATED BASES
• METHODOLOGY FOR FUNCTIONAL DESIGN OF LOW-LEVEL RIVER CROSSINGS IN SOUTH AFRICA
• MODELING FLOWSLIDES CAUSED BY STATIC LOADING
• MODELING THE STABILITY OF SAND FOUNDATIONS DURING EARTHQUAKES
• PORTABLE CROSSINGS FOR WEAK SOIL AREAS AND STREAMS
• RESILIENT PROPERTIES OF LABORATORY COMPACTED SUBGRADE SOILS
• RESPONSE OF PAVEMENT SYSTEMS TO DYNAMIC LOADS IMPOSED BY NONDESTRUCTIVE TESTS
• SHEETPILE CELL FILLING: FINITE ELEMENT MODEL VERIFICATION FOR TWO CASE HISTORIES
• TESTING AND MODELING OF TWO ROCKFALL BARRIERS