MODULUS 4.0: expansion and validation of the MODULUS backcalculation system

This report describes the Texas Transportation Institute's continuing efforts to upgrade the MODULUS backcalculation system. Enhancements have been made in several areas, including: 1. Inclusion of a procedure to estimate the depth to a stiff layer. 2. A method of assessing the non-linearity of the subgrade and computation of the optimum number of sensors to use in the backcalculation routine. 3. The replacement of the BISAR linear elastic procedure with the WES5 procedure recently developed by the US Corps of Engineers. The new MODULUS 4.0 is evaluated with monthly deflection data collected on 10 experimental sites for which all the layer materials have been tested in the laboratory. Validation of the system is attempted by using pavement sections instrumented with Multidepth Deflectometers. By simultaneously monitoring surface and depth deflections it is possible to quantify the effectiveness of the backcalculation system. Results show that the linear elastic model used in MODULUS produces reasonable layer moduli for pavements with thick asphalt surfacing. However, errors may result in using the linear elastic approach on thin pavements. The use of a stress dependent model which includes dilation substantially improves the match of measured and computed depth deflections on thin pavements. Preliminary results from a finite element backcalculation system have also been included.

• Corporate Authors:

  Texas Transportation Institute

  College Station, Texas  United States 
• Authors:
  • Rohde, G T
  • Scullion, T
• Publication Date: 1990-11

Language

• English

Media Info

• Pagination: 128p
• Serial:
  • Issue Number: 1123-3

Subject/Index Terms

• TRT Terms: Backcalculation; Computer programs; Deflectometers; Mathematical models; Measuring instruments; Pavement design; Pavement layers; Pavements; Stiffness; Structural analysis; Tests for suitability, service and quality
• ATRI Terms: Back calculation; Computer program; Deflectometer; Measuring equipment; Modelling; Pavement design; Pavement evaluation; Pavement layer; Stiffness; Structural analysis
• Subject Areas: Highways; Pavements;

Filing Info

• Accession Number: 01409102
• Record Type: Publication
• Source Agency: ARRB
• Files: ITRD, ATRI
• Created Date: Aug 24 2012 1:14AM