Bearing capacity increase of geotechnical structures through shear band enhancement

• Applicant: Professor Dr.-Ing. Jürgen Grabe
• Subject Area: Geotechnics, Hydraulic Engineering
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282413629

The research project is focused on the Cumputational Shear Zone Hardening (CSH), i. e. the numerical simulation of geotechnical constructions, where shear zones are strengened in order to increase the bearing capacity of foundations or to decrease the earth pressure on retaining walls. In the first funding period, experimental and numerical investigations based on CSH 1.0 has shown, that the strenthening of shear zones by means of cement injection led to a considerable increase in the load-bearing capacity. For this purpose the FEM solver OptumG2 was applied. In the second funding period, CSH 2.0 was implemented using the FEM solver Abaqus and the software MATLAB controlling Abaqus. A higher-order hypoplastic material model for soil was used, which can model the material transition from the natural soil to the strengthened soil. Various strengthening criteria were implemented to determine which material points of the soil should be strengthened. An automated procedure was developed by coupling Abaqus and Matlab. It was shown that the strengthening of shear zones leads to an increase in the ultimate load or the load that can be supported at comparable settlement of a foundation. The results could be verified by means of comparative computations in OptumG2. Based on the findings from the second funding period, in the third funding period the hypoplastic material model is extensively modified in order to make CSH 3.0 more generally valid and robust. A coupling to the Multicriterial Optimization with Evolutionary Algorithms (MOEA) will be realized in order to be enable to consider several optimization objectives in the calculation. Finally, technical, economical and ecological aspects of shear zone strengthening are evaluated.

• DFG Programme: Research Grants