Geotechnical properties of some evaporitic rocks

  • Bell F. G. 
Symposium on Engineering Geolgoical Problems of Construction on Soluble Rocks


The physical properties of four evaporitic rocks, anhydrite, gypsum, potash and rock salt, were investigated. Their respective specific gravities and dry densities show little variation and all four rock types have low porosity values. Anhydrite is by far the strongest material both in unconfined compression and in tension, followed by gypsum, potash and rock salt, in that order. The hardness values of these four rock types follow the same order as the strength values, to which they have a highly significant relationship. All four rock types exhibit some amount of plastic deformation prior to failure, anhydrite the least whilst rock salt shows the most. The value of Young's modulus tends to increase as the value of density, strength and hardness increases. Incremental creep tests indicate that rock salt suffers appreciable creep before failure, as does potash. Gypsum undergoes much more creep before failure than does anhydrite.


Gypsum Anhydrite Unconfined Compressive Strength Potash Failure Load 

Proprietes geotechniques de quelques roches evaporitiques


Les propriétés physiques de quatre roches évaporitiques—l'anhydrite, le gypse, la potasse et le sel—ont été examinées. Leurs poids spécifiques respectifs et leurs densités sèches ne varient pas beaucoup. Les quatre types de roches ont une porosité faible. En ce qui concerne la résistance à la compression et à la fraction, l'anhydrite est le matériau le plus résistant, suivi, dans l'ordre, par le gypse, la potasse et le sel. Pour la dureté, ces types de roches suivent le même ordre que la résistance, avec laquelle ils ont une relation très significative. Les quatre types montrent tous une certaine intensité de déformation plastique avant de se fracturer; la déformation de l'anhydrite est la moins grande cependant que le sel montre la déformation plastique la plus grande. Le module de Young tend à croître avec la densité, la résistance et la dureté. Les tests d'allongement croissant indiquent que les roches salées s'allongent considérablement avant de se fracturer, comme le fait la potasse. Le gypse s'allonge beaucoup plus avant la fracture que l'anhydrite.


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  1. BELL, F. G. (1975): Salt and Subsidence in Cheshire, England. Eng. Geol., 9, 237–247.CrossRefGoogle Scholar
  2. BROCH, E. and FRANKLIN, J. A. (1972): The Point Load Test. Int. Jour. Rock Mech. Min. Sci., 9, 669–697.CrossRefGoogle Scholar
  3. COLBACK, P. S. B. and WIID, B. L. (1965): The Influence of Moisture Content on the Compressive Strength of Rock. Proc. Rock Mech. Symp., Canadian Dept. Min. Tech. Surv., Ottawa, 65–83.Google Scholar
  4. DEERE, D. U. and MILLER, R. P. (1966): Engineering Classification and Index Properties for Intact Rock. Tech. Rept. No. AFWL-TR-65-115, Air Force Weapons Lab., Kirtland Air Base, New Mexico.CrossRefGoogle Scholar
  5. FARMER, I. W. (1968): The Engineering Properties of Rocks, Spon.Google Scholar
  6. FRANKLIN, J. A. (1970): Suggested Methods for Determining the Slaking, Swelling, Porosity, Density and Related Rock Index Properties. Res. Rept. D12, Imperial College, London.Google Scholar
  7. GEOLOGICAL SOCIETY ENGINEERING GROUP (1970): Working Party Report on the Logging of Cores for Engineering Purposes. Quart. Jour. Eng. Geol., 3, 1–24.CrossRefGoogle Scholar
  8. HARDY, H. R. (1966): A Loading System for the Investigation of the Inelastic Properties of Geologic Materials, Testing Techniques for Rock Mechanics. ASTM, STP 402, 232–265.Google Scholar
  9. OBERT, L., WINDES, S. L. and DUVAL, W. I. (1946): Standardized Tests for Determining the Physical Properties of Mine Rock. U. S. Bur. Min. Rep. Invest. 3891.Google Scholar
  10. RAMANA, Y. V. and VENKATANARAYANA, B. (1971): An Air Porosimeter for Determining the Porosity of Rocks. Int. Jour. Rock Mech. Min. Sci., 8, 103–118.Google Scholar
  11. WALSH, J. B. (1965): The Effect of Cracks on the Uniaxial Compression of Rocks. Jour. Geophys. Res., 70, 399–411.CrossRefGoogle Scholar
  12. WOODS, P. J. E. (1973): Potash Exploration in Yorkshire, Boulby Mine Pilot Borehole, Trans. Inst. Min. Met. (Section B, Applied Earth Science). 82, 99–106.Google Scholar

Copyright information

© International Association of Engineering Geology 1981

Authors and Affiliations

  • Bell F. G. 
    • 1
  1. 1.Department of Civil EngineeringTeesside PolytechnicMiddlesbroughUK

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