Das Verklebungspotential von Gesteinen im Tunnelbau

Translated title of the contribution: Clogging potential of rocks in tunnelling

Hans Schmidt

Research output: ThesisMaster's Thesis

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The aim of this thesis was to develop a simple method for studying the clogging potential of rocks in tunnelling. This method should work without time consuming laboratory tests and thus enable determination of clogging potential directly on site. First approach was the so-called stirring method. Here, a standard grout stirrer is rotary inserted into the prepared and uniformly compacted sample and the mass of adhering soil on the stirrer set in relation to the total mass of the soil used. The result of the stirring method represents the clogging index Iv in percent. Before starting the test series different geometries and speeds of the stirrer with respect to the induced adhesions were tested. The final series of tests was performed with 11 samples with different clogging potentials by Thewes. Each gradation of clogging potential was sampled at least once. The results show that the stirring method generally correlates well with the clogging potential by Thewes. An exception here are samples with pulpy consistency, these have a 3.5 % to 4.0 % increased clogging index. So the clogging index of these samples have to be reduced by this value. Then a clogging index from about 14 % indicates to high clogging potential. Medium clogging potential is given when the clogging index is about 11 % to 13 %. A clogging index below about 10 % indicates low clogging potential. Parallel to the determination of clogging index the water content was determined for each sample. Pulpy consistency occurred at a water content about 32 %. Another approach represented the vane testing device method. In this case a shear test determines the shear resistance between the soil and the metal surface of a suitable sample vessel (aluminium pipe e.g.) is performed by means of a laboratory vane testing device. The angular speed of the vane probe is set constant and the receivable torque is measured. First experiments were carried out with an angular speed of 6 °/min. These tests showed that the homogenous introduction of the sample in the sample vessel will be the determining factor for the success. In particular, the horizontal stresses during insertion have to be in mind. In this thesis results of only two test trials of the vane testing device method and the consequent initial findings are presented. A complete set of tests would be beyond the scope of this work.
Translated title of the contributionClogging potential of rocks in tunnelling
Original languageGerman
  • Pittino, Gerhard, Supervisor (internal)
Award date16 Dec 2016
Publication statusPublished - 2016

Bibliographical note

embargoed until null


  • adhesion potential
  • tunneling

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