Back-Calculation of Soil Modulus from PFWD Based on a Viscoelastic Model. (6th November 2019)

• Record Type: Journal Article
• Authors: Zhang, Rui; Ren, Tianzeng; Khan, Md Ashrafuzzaman; Teng, Yusheng; Zheng, Jianlong
• Other Names: Annamdas Venu G. M. Academic Editor.
• Is Part Of: Advances in civil engineering. Volume 2019(2019)
• Publication Date: 2019-11-06
• Subjects: Civil engineering -- Periodicals; Civil engineering; Periodicals; 624
• DOI: 10.1155/2019/1316341
• Languages: English
• ISSNs: 1687-8086

Abstract

Abstract : To improve the accuracy of back-calculation of soil modulus using the portable falling weight deflectometer (PFWD), a viscoelastic method (VEM) overcoming the limitations of the conventional linear elastic method (LEM) was proposed. A quasi-static dynamic analysis technique of Laplace transformation and a modified Gauss–Newton optimization algorithm were adopted in the proposed method. The back-calculation program was compiled with MATLAB. The effectiveness of the proposed method was verified with the in situ plate load test (PLT) conducted on a highway embankment. In situ test results showed that a time lag existed between the peaks of deflection and load, and load-deflection curves were nonlinear, which indicated the viscoelastic nature of the soil. The back-calculated modulus using the LEM and VEM was higher than that using the PLT. In the case of low stiffness soil, the average error of back-calculation using the LEM and VEM was 53.1% and 14.8%, respectively. However, for stiffer soil, the average error of back-calculation using the LEM and VEM method was 12.4% and 4.3%, respectively. Moduli of back-calculation using LEM and VEM methods were used to perform flexible pavement analysis, which showed that with an 8% reduction of modulus, the pavement service life reduced by 25%. More accurate estimation of modulus can save maintenance cost in the future.