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

土与土工格栅加固的结合产生了一种复合材料，这种材料通常用于广泛的岩土工程应用。在研究范围内，基于大型双轴压缩试验，研究了平原应变条件下复合材料“土工格栅加筋土”的主应力-应变特性。然而，由于对土工格栅与土体之间荷载传递的认识有限，特别是对周围土体对土工格栅的间接活化有实际的研究需要。扩大研究的目的是探讨除了轴承和摩擦效应之外，还有哪些额外的相互作用机制起作用。因此，调查的重点是确定动员联锁效应。此外，全局“约束”效应必须基于局部荷载传递机制来解释。因此，为了获得复合材料在“准”单元试验中的应力-应变行为，需要对双轴压缩试验的实验设置进行修改。此外，将在透明土样中进行土工格栅加筋相互作用试验。相互作用试验的目的是识别有效的相互作用机制，并基于数字图像相关方法分析土工格栅与土的空间位移以及它们之间的相对运动。在这两个试验中，将使用常规土工格栅和土壤，以避免规模效应。准单元相互作用试验和透明相互作用试验的结果相结合，可以对土-土工格栅相互作用进行定性和定量分析。在实验结果的基础上，进一步完善相互作用模型。由于在修正试验中联锁效应明显，除土工格栅拉力外，还必须考虑竖向和水平应力。该相互作用模型的结果表明，接收到的与应力和位移相关的摩擦系数可作为土工格栅加筋土有限元计算中的界面单元。

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.