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Publication Number:  FHWA-HRT-13-066    Date:  August 2013
Publication Number: FHWA-HRT-13-066
Date: August 2013


Geosynthetic Reinforced Soil Performance Testing - Axial Load Deformation Relationships


The results of the PT research performed on GRS composites leads to several important conclusions. General conclusions include the following:

  1. The performance test can be used to model the load-deformation behavior of a particular GRS composite and is repeatable. Based on equivalency comparisons, the ratio of the measured vertical capacity in a PT to that of the same GRS in plane strain is near unity, and the stiffness of what a plane strain GRS composite might experience (such as an abutment) is up to 3 times higher (on the conservative side) compared to what is measured in a GRS PT (section 5).

  2. A two-post frame with single hydraulic jacks produces more even load distribution than a two bolted channel beams in combination with four hydraulic jacks.

The load-deformation relationship of GRS composites depends on several parameters including preloading, aggregate angularity, compaction level, presence of bearing bed reinforcement, and facing confinement.

Both open-graded and well-graded aggregates can be used as the reinforced backfill in GRS composites; each has their advantages and disadvantages. The PT results further distinguished the effect aggregate selection can have on the behavior of GRS.

The relationship between reinforcement strength and spacing was investigated through a series of PTs with the same Tf/Sv ratio.

The primary purpose of PTs is to provide a designer with the unique stress-strain properties of a particular GRS composite for use in design. There is an empirical method and an analytical method currently available for GRS by FHWA.(1)

Finally, a reliability analysis for the soil-geosynthetic capacity equation (figure 8) was performed on the 16 PTs taken to failure in this study, along with previous results from additional GRS testing found from the literature.


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