Soil liquefaction caused by earthquakes is a devastating occurrence that can compromise the foundations of buildings and other structures, leading to considerable economic losses. Among the new remedies against liquefaction, Induced Partial Saturation (IPS) is regarded as one of the most promising technologies. In order to improve liquefaction resistance and the fluid phase's compressibility, gas or air bubbles are introduced into the pore water of sandy soils. This article deals with the general laboratory evaluation of a sand under partially saturated conditions and under cyclic loading to assess if this technology is applicable for a ground improvement of the examined soil. The use of the Axis Translation Technique for sample desaturation and diffusion-stable butyl membranes significantly influences the laboratory results. Additionally, it is found that the trapped air bubbles of the partially saturated samples act like a damping mechanism, which are reflected in the stress paths of the deviator stress q over the mean pressure p with an inclination of 1 : 3. Zum Verfl & uuml;ssigungsverhalten von teilges & auml;ttigtem SandDie durch Erdbeben verursachte Bodenverfl & uuml;ssigung ist ein verheerendes Ereignis, das die Fundamente von Geb & auml;uden und anderen Bauwerken gef & auml;hrden und zu erheblichen wirtschaftlichen Verlusten f & uuml;hren kann. Die induzierte partielle S & auml;ttigung (Induced Partial Saturation, IPS) gilt als eine der vielversprechendsten Technologien unter den neuartigen Baugrundverbesserungen gegen Verfl & uuml;ssigung. Um den Verfl & uuml;ssigungswiderstand und die Kompressibilit & auml;t der fl & uuml;ssigen Phase zu verbessern, werden dabei Gas- oder Luftblasen in das Porenwasser sandiger B & ouml;den eingebracht. Dieser Beitrag besch & auml;ftigt sich mit der generellen labortechnischen Evaluierung eines Sandes unter teilges & auml;ttigten Verh & auml;ltnissen und unter zyklischer Beanspruchung zur Beurteilung, inwiefern sich diese Baugrundverbesserung f & uuml;r den untersuchten Boden eignet. Die Verwendung der Axis Translation Technique zur Probenentw & auml;sserung und die Verwendung von diffusionsstabilen Butylmembranen haben einen erheblichen Einfluss auf die Laborergebnisse. Au ss erdem ist festzustellen, dass die eingeschlossenen Luftblasen der teilges & auml;ttigten Proben wie eine D & auml;mpfung wirken und sich in den Spannungspfaden der Deviatorspannung q & uuml;ber dem mittleren Druck p mit einer Neigung 1 : 3 widerspiegeln.

Investigations on the liquefaction resistance of an open-cast lignite mine soil under loading by earthquake-typical signals For the embankments of the planned opencast mining lakes in the Rhenish mining area, the proof of the stability under earthquake action must be provided. According to the guideline for the investigation of the stability of slopes in lignite opencast mines (RfS - Richtlinie f & uuml;r Standsicherheitsuntersuchungen [1]), the permanent slopes must be designed and constructed in such a way that a soil liquefaction is not to be expected. For the proof, in which actions and soil resistances are locally compared with each other, the irregular earthquake signal is converted into a regular signal with an equivalent number of cycles and constant amplitude. In this paper, this conversion is investigated for a typical earthquake signal of the Rhenish area, which was obtained from a dynamic finite element calculation. Triaxial tests with vertical cyclic loading and hollow cylinder triaxial tests with cyclic torsional loading are performed to investigate the liquefaction behaviour of an opencast mine soil under the influence of this earthquake signal. The results of these tests are compared with data from further tests with constant amplitude. It can be shown that the factor beta for converting irregular to regular signals depends on the type of loading and the magnitude of the static shear or deviatoric stress. On the basis of the experiments, recommendations for the choice of beta for the Rhenish mining area are given.