Thermisches Berechnungsmodell zur Reichweitenermittlung von DSV-Säulen

15.11.2004 - 14.12.2010
Research funding project
In order to detect/avoid damage in consequence of low quality of improved soil obtained from the application of jet grouting, continuous quality control of the jet-grouting work is of essential importance. Nowadays, test columns are installed for this purpose, which, after the subsequent excavation, provide insight into the dimensions of the improved soil body. In addition to the delay of 4-5 days caused by the installation and excavation of test columns, quality control of jet-grouting work is restricted to upper soil layers, where the test column was excavated. Within this research project, a novel method for quality control of ground improvement by means of jet grouting shall be developed. Based on first measurements conducted at construction sites, a correlation between the properties of the jet-grouted column and the temperature history in the hydrating column was identified. Exploiting this thermochemical coupling of hydrating cement-based materials, back analysis shall provide access to the dimensions of the jet-grouted column and the material properties of the improved soil. The quality of the obtained results strongly depends on the chemical/thermal properties of the involved materials (improved soil and surrounding soil). The estimation of these properties by means of micromechanical models is dealt with in the first part of this research project. These models are validated in the second part by means of thermal laboratory experiments. Based on the validated micromechanical model and an appropriate back analysis scheme at hand, the hydration process of jet-grouted columns is simulated and validated by test columns at different construction sites. In addition to the dimensions of the jet-grouted column and the cement content, the anticipated analysis scheme provide access to the degree of hydration in the column and, hence, to the evolving material properties. Finally, use of the anticipated analysis scheme should provide results already after 1-2 days in different columns and different depths and, thus, allows the optimization of the ongoing ground-improvement work.

People

Project leader

Project personnel

Institute

Contract/collaboration

  • Porr Technobau und Umwelt AG, Abteilung Grundbau

Grant funds

  • FFG - Österr. Forschungsförderungs- gesellschaft mbH (National) Austrian Research Promotion Agency (FFG)

Research focus

  • Composite Materials: 30%
  • Structure-Property Relationsship: 40%
  • Modeling and Simulation: 30%

Keywords

GermanEnglish
Bodenverbesserungsoil improvement
Düsenstrahlverfahrenjet-grouting
Hydratationhydration
thermochamische Kopplungthermochemical coupling
Mikromechanikmicromechanics

Publications