Incremental stress-strain-behaviour of sand at low-cycle loading and application on excavation models

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An important aspect in the design of inner-city-located excavations is the assessment of the service ability and at the same time the deformation estimation of adjacent pits buildings. Recent research results have shown the meaning of geotechnical construction processes and the occurring deformations at high- and low-cycle loading-processes and changes of stress-states respectively. The stress-path-dependent stiffness at first-, un- and reloading processes when simulating earth-pressure, wall-deformations and settlements plays an important role. At the moment, the consideration of geotechnical construction processes and their effects on construction-states is – apart from some exceptions – not state of the art yet. In addition to that, common constitutive models are often not able to predict the deformation due to these processes realistically or accurately enough.To improve the prediction of deformations of excavation-pit-walls, the envisaged research-projects shall produce basic experimental results to support the development of a new constitutive powerful model and to facilitate its calibration and validation. By applying the results of the other researchgroup- teams (e.g. contact-elements) the performance of this model shall be tested by calculating deformations with a numerical excavation-model, especially developed for this purpose. Based on these results and collaborating with TP6 the opening question, i.e. the prognosis of deformations due to geotechnical construction processes during the installation of vibrated and grouted piles, may eventually be answered.