Prediction research of deformation modulus of weak rock zone under in-situ conditions

  • Yong ZhangEmail author
  • JiangDa He
  • Yufeng Wei
  • Dexin Nie


Weak rock zone (soft interlayer, fault zone and soft rock) is the highlight of large-scale geological engineering research. It is an important boundary for analysis of rock mass stability. Weak rock zone has been formed in a long geological period, and in this period, various rocks have undergone long-term consolidation of geostatic stress and tectonic stress; therefore, under in-situ conditions, their density and modulus of deformation are relatively high. Due to its fragmentary nature, once being exposed to the earth’s surface, the structure of weak rock zone will soon be loosened, its density will be reduced, and its modulus of deformation will also be reduced significantly. Generally, weak rock zone can be found in large construction projects, especially in the dam foundation rocks of hydropower stations. These rocks cannot be eliminated completely by excavation. Furthermore, all tests nowadays are carried out after the exposure of weak rock zone, modulus of deformation under in-situ conditions cannot be revealed. In this paper, a test method explored by the authors has been introduced. This method is a whole multilayered medium deformation method. It is unnecessary to eliminate the relatively complete rocks covering on weak rock zone. A theoretical formula to obtain the modulus of deformation in various mediums has also been introduced. On-site comparative trials and indoor deformation modulus tests under equivalent density conditions have been carried out. We adopted several methods for the prediction researches of the deformation modulus of weak rock zone under in-situ conditions, and revealed a fact that under in-situ conditions, the deformation modulus of weak rock zone are several times higher than the test results obtained after the exposure. In a perspective of geological engineering, the research findings have fundamentally changed peoples’ concepts on the deformation modulus of weak rock zone, provided important theories and methods for precise definition of deformation modulus of deep weak rock zone under cap rock conditions, as well as for reasonable engineering applications.


Weak rock zone In-situ conditions: Stress Confining pressure Deformation modulus Multilayered 


  1. Palmström A, Singh R (2001) The deformation modulus of rock masses-comparisons between in situ tests and indirect estimates. Tunnelling and Underground Space Technology, 16( 3): 115–131.CrossRefGoogle Scholar
  2. Bieniawski ZT (1978) Determining rock mass deformability: experience from case histories. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts;15:237–47.CrossRefGoogle Scholar
  3. Gokceoglu C,. Sonmez H, Kayabasi A (2003) Predicting the deformation moduli of rock masses. International Journal of Rock Mechanics & Mining Sciences 40(2003)701–710.CrossRefGoogle Scholar
  4. Chilingar GV, Knight L(1960) Relationship between pressure and moisture content of kaolinite, illite, and montmorillonite clays. AAPG Bulletin,44(1): 101–10.Google Scholar
  5. Chilingar GV, Rieke III HH, Robertson Jr JO (1963) Relationship between high overburden pressures and moisture content of halloysite and Dickite clays. GSA Bulletin 74(8):1041–1048.CrossRefGoogle Scholar
  6. Hoek E, Diederichs MS (2006) Empirical estimation of rock mass modulus. International Journal of Rock Mechanics & Mining Sciences 43:203–215.CrossRefGoogle Scholar
  7. Han WF, Zhang XG, Nie DX (1988) The study of physical properties of fault gauges and their distribution features. Proceedings of the 3rd Science Conference of Chinese Society for Engineering Geology. Chengdu: Chengdu University of Science and Technology Press, 1988. pp 186–190.Google Scholar
  8. Heberg HD. Gravitational compaction of clays and shales (1963) American Journal of Science (Series 5) 31:241–287.Google Scholar
  9. Hoek E, Brown ET (1997) Practical estimates of rock mass strength. International Journal of Rock Mechanics and Mining Sciences 34(8):1165–1186.CrossRefGoogle Scholar
  10. Hoshino K, Inami K (1977) Stages of compaction as defined from change of mechanical properties. Japanese Association for Petroleum Technology 40:166–173.Google Scholar
  11. Hoshino K (1984) Effect of geological factors on mechanical propertiesof rocks. In: Proc 6th Symp Rock Mechanics. Japan pp 145–150.Google Scholar
  12. Lei CD, Zeng JQ, Shao XM, Guo SN (2002) Testing study on deformation of weak rocklayers. Chinese Journal of Rock Mechanics and Engineering 21(9):1295–1301Google Scholar
  13. Li D, Zhang M, Wang ZW (2006). Suggested method for deformability test of layered rock masses. Rock and Soil Mechanics 10:1156–1160.Google Scholar
  14. Meigh AC, Wolski W (1980) Design parameters for weak rocks. In: Proc 7th European Conference on Soil Mechanics & Foundation Engineering. Brighton, British Geotechnical Society. pp 315–321.Google Scholar
  15. Nicholson GA, Bieniawski ZT (1990) A nonlinear deformation modulus based on rock mass classification. Geotechnical and Geological Engineering 8(3): 181–202.Google Scholar
  16. Nie DX, Zhang XG, Han WF (1990) Studies on the correlation between the effect of confining pressure and the physical and mechanical properties of weak intercalations. In: Proceedings of the 6th International Congress International Association of Engineering Geology. pp 2473–2479.Google Scholar
  17. Nie DX, Zhang XG, Han WF (1990) The correlation between confining pressure effect and physical and mechanical properties of weak intercalations. Journal of Geological Hazards and Environment Preservation, 1(2):30–35. (In Chinese)Google Scholar
  18. Nie DX, Zhang XG, Han WF (1972). The main problems in the evaluation of engineering geology of weak layer zones. In: Proceedings of the 4th Science Conference of Chinese society for Engineering Geology. Beijing: Ocean Press. pp 603–609. (In Chinese)Google Scholar
  19. Nie DX (1983) The effect of ground stress upon the shear strength of Argillaceous materials in weak intercalations. The Conference of Chinese Science and Technology of Water Conservancy and Hydroelectric Power for Youth Cadres in 1983. Beijing: Water Conservancy and Hydroelectric Power Press. pp 153–158.(In Chinese)Google Scholar
  20. Nie DX (2000) The Study of field features of rock mass. Journal of Engineering Geology 8(3):41–45.Google Scholar
  21. Rieke HH (1970) Compaction of argillaceous sediments. Los Angeles: University of Southern Califorinia.(In Chinese)Google Scholar
  22. Serafim JL, Pereira JP (1983) Considerations on the geomechanical classification of Bieniawski. In: Proceedings of the Symposium on Engineering Geology and Underground Openings, Lisboa, Portugal. pp 1133–1144.Google Scholar
  23. Skempton AW (1970) The consolidation of clays by gravitational compaction. Quarterly Journal of the Geological Society 125(3):373–411.Google Scholar
  24. Zhang YH, Shi AC, Zhou HM et al. (2008) Explanation and application of data obtained in deformation test of central hole. Chinese Journal of Rock Mechanics and Engineering 27(3):589–595 (In Chinese)Google Scholar

Copyright information

© Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.School of Hydraulic and Hydroelectric EngineeringSichuan UniversityChengduChina
  2. 2.State Key Laboratory of Geohazard Prevention and Geoenvironment ProtectionChengdu University of TechnologyChengduChina

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