THE DEICHMANN ROCK MECHANICS LABORATORY OF THE NEGEV
Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 , Israel.


Introduction

The Rock Mechanics Laboratory of the Negev has been developed in order to meet the rising demand for advanced geological engineering input in current projects in Israel which have an impact on the environment, with particular emphasis on the Negev. The laboratory was established in April 1994.

The role of the Lab in the development of the Negev

The Negev is rapidly developing and its infrastructure is being improved continuously. Several sophisticated projects are planned and some are already under way. All projects involve the interaction of man with the environment, by the introduction of new loads to the rock mass. The successful execution of projects which involve surface and underground excavation depends therefore on the availability of a testing facility which can simulate the excavation induced loads on representative samples of the rock mass. Rock engineering projects which are currently under design or construction include:

The Rock Mechanics Laboratory of the Negev has been involved in the design and planing of such projects since its was established in April 1994. Selected research projects in geological engineering and rock mechanics can be viewed at the website of Prof. Yossef H. Hatzor, director of the geological engineering program . In addition, basic research in rock physics and in particular on electromagnetic radiation during rock fracture processes is conducted at the lab since its establishment. The electromagnetic radiation research group is directed by Prof. Dov Bahat and details can be found in his home page.
 

Technical description of the Lab

  1. Hydraulic, stiff, closed-loop servo controlled triaxail system. Load frame stiffness 5*109 N/m (TerraTek model FX-S-33090 ). Two control modes are possible for the axial piston: Load and Displacement. Axial force capacity: 1.4 MN. Confining pressure capacity: 70 MPa. Simultaneous electronic measurement of axial and radial strain using a two special four arm strain cantilever system sets with a maximum strain range of 7% . Precision: 0.25 - 0.5% linearity full scale on all strain/displacement transducers as well as load cells. Two load cells (LC) are currently in service: 1000 kN LC for strong rocks, and a 222 kN LC for weak rocks to allow for better resolution in low stress measurements.  Using the close-loop system the following tests can be performed:

    • Unconfined Compression tests
    • Triaxial Compression tests
    • Post Peak tests
    • Creep tests
    • Hydrostatic Compression tests
    • Segment tests
    • Uniaxial Strain tests
       
  2. Hydraulic, stiff, closed-loop servo controlled, direct shear system. Load frame stiffness 7.0 MN/m (TerraTek DS - 4250).Normal force capacity: 1000 kN, Shear force capacity: 300kN. Shear box dimensions: 150mmX150mmX300mm. Normal load measured with a 1000kN LC with 0.5% linearity full scale. Shear load measured with a 300 kN LC with 0.5% linearity full scale. Vertical (normal) displacement measured with four 50mm range LVDT's with 0.25% linearity full scale. Shear displacement measured with two 50mm range LVDT's  with 0.25% linearity full scale.
     

  3. Manual, hydraulic, mini-load frame for Brazilian, Point Load, and Uniaxial tests according to ASTM and ISRM standards (SBEL model PLT-75).
     

  4. Ultrasonic wave velocity for P and S wave determination on cores according to ASTM and  ISRM standards.
     

  5. Sample preparation lab, fully equipped with a high precision drill press, saw, and surface grinder. NX size solid cylinders are prepared according to ASTM and ISRM standards regarding end roughness (smaller than 0.02mm) and perpendicularity (to within 0.005 radians).
     

  6. Soils Classification Equipment (ASTM).
     

  7. Schmidt Hammer test device (ASTM, ISRM).
     

  8. Slake durability test device (ASTM, ISRM).
     

  9. Helium porosimeter (CoreTest Inc., model PHI-220) for direct porosity measurements.