Laboratory pullout test study on the influence zone of geosynthetics

Jianbo Fei,Haipeng Wu,Yuxin Jie,Ting Zhou

doi:10.1177/1558925020906674

Jianbo Fei, Haipeng Wu + Show 2 more

Open Access

https://doi.org/10.1177/1558925020906674

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Abstract

Conventional pullout test devices are mainly designed to measure the shear strength indices of the geosynthetics–soil interface. This article introduces a new model container to study the influence zone of geosynthetics in pullout test. Several basic image processing methods were employed to analyze the grain motion of two gravel compositions in pullout tests. The trajectories of grains in the gravel differ at different heights; specifically, a more active motion was observed if the grain was closer to the geosynthetics. Moreover, grains were found to move not only horizontally but also vertically as well as to rotate on pulling out the geosynthetics. The range of a grain on the move is almost constant during the pullout and determines the influence zone of the geosynthetics. Image processing revealed that the influence zone was eight times the average grain size above the geosynthetics and 4–5 times the average grain size below the geosynthetics. The boundary condition thus significantly affects the influence zone.

Highlights

Soils, reinforced using geosynthetics, have been used in the construction industry since the 1960s
Benefits of smaller reinforcement spacing for performance improvements in such soils were realized in both practical and experimental studies;[2,3,4,5] in general, the results suggest that the smaller the spacing, the better the reinforcement efficiency
The video taken during the tests were analyzed using several basic image processing methods, so that the motion of grains adjacent to the geosynthetics could be investigated

Summary

Introduction

Soils, reinforced using geosynthetics, have been used in the construction industry since the 1960s. In narrowing down the best spacing, several meaningful studies have focused on soil–geosynthetic interactions such as geogrid properties influence, boundary conditions effect, and displacement rate.[13,14,15,16,17,18,19,20,21] Aside from these studies, the influence zone of geosynthetics is deemed important in determining a reasonable reinforcement spacing.[22] This influence zone is governed by the thickness of the interface between soil and geosynthetics.

Results

Conclusion