Effect of Particle‐Size Gradation on Coarse Sand‐Geotextile Interface Response in Cyclic and Postcyclic Direct Shear Test

Abstract

In order to investigate the influence of sand particle-size gradation on cyclic and postcyclic shear strength behaviour on sand-geotextile interfaces, a series of monotonic direct shear (MDS), cyclic direct shear (CDS), and postcyclic direct shear (PCDS) tests were performed using a large-scale direct shear apparatus. The influence of cyclic shear history on the direct shear behaviour of the interface was studied. The results indicated that cyclic shear stress degradation occurred at the sand-geotextile interface. Shear volumetric contraction induced by the cyclic direct shear increased with the increase in cycle number. The lowest final contraction value was observed in discontinuously graded sand. In the MDS tests, there were great differences in interface shear strength due to the different particle-size gradations, whereas the differences between shear volumes were negligible. In the PCDS tests, the shear stress-displacement curves exhibited postpeak stress hardening behaviour for different particle-size gradations, and differences in shear volumes were detected. The well-graded sand-geotextile interface had a higher value of shear stiffness and a higher damping ratio relative to the other interfaces. Postcyclic shear stress degradation was observed for the discontinuously graded sand-geotextile interface.

Shear Characteristics of the Interface between Recycled Concrete Aggregates and Various Geosynthetics

“…Because the shear area remained unchanged in the test, the vertical displacement development law of the contact surface could represent the shear body deformation development law of the shear surface during the shearing process. In this test, the shear dilatation was positive and the shear shrinkage was negative [24]. As shown in Figure 5(b), in the initial stage of shearing, both the gravel and the shear surface of RCA had a short-term shear shrinkage deformation, and then, the gravel and RCA shear surfaces expanded relatively rapidly.…”

Research on Shear Behavior of Sand–Structure Interface Based on Monotonic and Cyclic Tests

“…Two series of tests were conducted in this study, one was the monotonic shear test of sand-steel interface, which considered the influence of factors such as normal stress, interface roughness, and relative density of sand on the test. In the shear test studies of sand conducted by Punetha [30], Wang [31] and Kou [32] and many other researchers, the shear rate was 0.2-1.2 mm/min. In order to ensure the stability and reliability of the test data, this test controlled the shear rate at 0.3 mm/min and stopped the test when the fixed shearing displacement had reached 10 mm.…”