Principle Investigation and Description of the Stress-Strain Behaviour of the Composite Material "Geogrid Reinforced Soil"

• Applicant: Professor Dr.-Ing. Martin Ziegler
• Subject Area: Geotechnics, Hydraulic Engineering
• Term: from 2014 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263996107

The combination of soil and geogrid reinforcement leads to a composite material, which is commonly used in a wide range of geotechnical applications. Within the scope of the conducted investigations, the principle stress-strain behavior of the composite material "geogrid reinforced soil" was investigated based on large-scale biaxial compression tests under plain strain conditions. However, due to the limited understanding of load transfer between soil and geogrid, there exist an actual need for research especially on the indirect activation of the reinforcement by the surrounding soil. The aim of the enlarged research is to investigate, which additional interaction mechanisms act besides the bearing and friction effects. Hereby the focus of the investigation is to determine the mobilization of the interlocking effect. Moreover, the global “constraining” effect has to be explained based on the local load transfer mechanisms. Therefore, the experimental setup of the biaxial compression tests will be modified in order to obtain the stress-strain behavior of the composite material in “quasi”-element tests. Additionally, interaction tests with geogrid reinforcement in transparent soil specimens will be carried out. The objective of the interaction tests is to identify the effective interaction mechanisms and to analyze the spatial displacements of geogrid and soil as well as the relative movement between these components based on the digital image correlation method. In both tests, regular geogrids and soils will be used in order to avoid scale effects. The combination of the results obtained from quasi”-element and transparent interaction tests enables a qualitative and quantitative analysis of the soil-geogrid-interaction.Based on the experimental results, the interaction model will be further improved. As the interlocking effect will be distinctive in the modified tests, the vertical and horizontal stresses have to be considered beside geogrid tensile forces. As a result of the interaction model, the received stress and displacement depended friction coefficients can be used for interface elements in finite element calculations of geogrid-reinforced soil.

• DFG Programme: Research Grants