The geotechnical lab

 

Contact

Name

Lena-Maria de Vries

Laboratory Management

Phone

work
+49 241 80 96788

Email

E-Mail
 

The geotechnical laboratory

The Department of Engineering Geology and Hydrogeology has a geotechnical laboratory which is used for a variety of purposes. The laboratory work takes place in two sections and serves teaching and research in the field of soil and rock mechanics.

Teaching

Teaching includes internships and the supervision of bachelor and master students.With the help of various experiments the following soil-physical characteristics can be determined according to DIN/ ISO:

  • Water content
  • Grain size distribution by sieving
  • Particle size distribution by slurry analysis
  • Grain density
  • yield and roll-out limit
  • Shrink limit
  • Water absorption capacity
  • Lime content
  • Loss on ignition
  • Compaction behaviour according to Proctor
  • Compression behaviour with impeded lateral expansion
  • Shear Strength

Research

Apart from teaching activities, the laboratory is used for conducting geotechnical experiments in various research projects - often involving students in the context of final theses. In the following three projects will be presented as examples to give a clear impression of the laboratory activities.

Hydromechanical characterisation of the Opalinus Clay

Opalinus clay represents a promising lithological formation for the final disposal of radioactive waste. In the geotechnical laboratory of LIH the hydromechanical behaviour of corresponding clay samples is investigated in triaxial compression tests (axial load: 100 kN, restraint up to 30 MPa). In the two cells of the device, the samples can be isostatically saturated and consolidated and then sheared off under the test frame at very low deformation rates.

Direct shear tests on 3D-printed specimens

Modern 3D printing techniques enable the production of sandstone-analogue specimens with defined and highly reproducible properties and (fracture) geometries. By means of direct shear tests (100kN) on such specimens, the influence of different parameters on the shear strength can be investigated in a much more isolated way than is possible with natural specimens.

Soil liquefaction in landslide deposits

In a further laboratory experiment, the pore pressure development in landslide deposits during subsequent events will be investigated under undrained as well as drained conditions. For this experiment, a plexiglass box was built in which the soil sample is fully saturated before the experiment begins. In order to simulate the impact of a landslide on the debris deposits at the foot of the slope, a second volume of soil is dropped into the Plexiglas box from above using a funnel. Sensors positioned on the sides of the box continuously record the pore pressure in the sediment.

Available devices

The LIH has extensive equipment for carrying out experiments in the laboratory and on site:

laboratory equipment field instruments
  • Frame shearing machine for loose rock
  • Direct shearing device for rock samples (100kN)
  • Triaxial press (axial load:100kN, clamping up to 30 MPa)
  • climate chamber with a temperature range of -10°C to +30°C and a relative humidity of 30% to 95%
  • High-resolution camera for Digital Image Correlation (DIC)
  • Various data acquisition systems for strain, pore pressure and force measurement
  • Borehole camera for the inspection of boreholes
  • surveryor's level device for measuring differences in height
  • Field vane probe for the determination of the layer-oriented, undrained shear strength in the borehole
  • Guelph permeameter to determine the saturated hydraulic conductivity of the soil
  • Cobra for ram core probing
  • Dynamic probe for dynamic probing
  • Pürkhauer and cutting cylinder for sampling
  • Laser scanner for the observation of surface deformations
  • FO-DTS (Fibre optical distributed temperature sensing) for fibre optical temperature measurement in boreholes up to 300m depth
  • High pressure pumps + flowboard for performing pressure and rate controlled hydraulic tests and stimulations with up to 100 l/min at 20 MPa in solid rock
  • High resolution camera for DIC
  • High resolution camera including range finder, GPS system and software for digital photogrammetry