The Next Generation of Testing with LWD to Assess the In-Situ Permanent Deformation of Geomaterials under Repeated Loading

Abstract

This study focuses on evaluating in-situ permanent deformation in fine-grained soils through the application of a specially designed Repeated Light Weight Deflectometer (LWD) test. The primary objective is to investigate how water content and applied stress levels influence permanent deformations in the field. Additionally, the study aims to assess the utility of LWD-derived data in predicting permanent strains. Results indicate a significant correlation between permanent deformations and key parameters, such as the number of load cycles, applied stress levels, and water content. It is observed that permanent deformations increase proportionally with these variables, particularly in cases of elevated water content and higher stress levels. The soil demonstrates an increased susceptibility to accumulating permanent deformations, persisting even after numerous LWD load applications. In response to these findings, a predictive model is presented to estimate accumulated permanent strain, exhibiting a commendable fit to data for moisture contents up to 22%, corresponding to an average water content of 19%. Ultimately, this research underscores the pivotal role of water content and applied stress levels in determining permanent deformation characteristics in fine-grained subgrade soils. The study also provides a valuable predictive model derived from repeated in-situ LWD measurements, offering critical insights into the field permanent deformation behaviour of subgrade soil. This simple and time-saving test enhances engineering practices for pavement design and construction.

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