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

土壤和土工格栅加固的组合导致复合材料，其通常用于广泛的岩土工程应用中。在所进行的调查范围内，复合材料“土工格栅加筋土”的主要应力-应变行为进行了调查的基础上，在平面应变条件下的大型双轴压缩试验。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加筋体的间接激活作用的研究还存在实际需要。扩大研究的目的是调查除了轴承和摩擦效应之外，还有哪些额外的相互作用机制。由此考察的重点是确定动员的连锁效应。此外，全球的“约束”的效果，必须解释的基础上的局部负荷转移机制。因此，双轴压缩试验的实验装置将被修改，以获得复合材料的应力-应变行为的“准”单元测试。此外，将在透明土样中进行土工格栅加固的相互作用试验。相互作用试验的目的是确定有效的相互作用机制，并分析土工格栅和土壤的空间位移以及这些组件之间的相对运动的基础上的数字图像相关方法。在这两项测试中，将使用常规的土工格栅和土壤，以避免规模效应。将准单元试验结果与透明试验结果相结合，可以对土工格栅与土的相互作用进行定性和定量分析，并在此基础上进一步完善了土工格栅与土的相互作用模型。由于在修正试验中联锁效应将是显著的，除了土工格栅拉力外，还必须考虑竖向和水平应力。该相互作用模型的结果表明，与应力和位移相关的摩擦系数可用于土工格栅加筋土有限元计算中的接触面单元。

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.