Theoretical model of effective stress coefficient for rock/soil-like porous materials
Physical mechanisms and influencing factors on the effective stress coefficient for rock/soil-like porous materials are investigated, based on which equivalent connectivity index is proposed. The equivalent connectivity index, relying on the meso-scale structure of porous material and the property of liquid, denotes the connectivity of pores in Representative Element Area (REA). If the conductivity of the porous material is anisotropic, the equivalent connectivity index is a second order tensor. Based on the basic theories of continuous mechanics and tensor analysis, relationship between area porosity and volumetric porosity of porous materials is deduced. Then a generalized expression, describing the relation between effective stress coefficient tensor and equivalent connectivity tensor of pores, is proposed, and the expression can be applied to isotropic media and also to anisotropic materials. Furthermore, evolution of porosity and equivalent connectivity index of the pore are studied in the strain space, and the method to determine the corresponding functions in expressions above is proposed using genetic algorithm and genetic programming. Two applications show that the results obtained by the method in this paper perfectly agree with the test data. This paper provides an important theoretical support to the coupled hydro-mechanical research.
Key wordsrock/soil-like porous materials generalized model for effective stress coefficient tensor equivalent connectivity index of pore genetic algorithm
Unable to display preview. Download preview PDF.
- Terzaghi, K.V., Die Berechnung der durchassigkeitsziffer des Tones aus dem Verlauf der hydrodynamischen Spannungserscheinungen. Sitzungsber. Akad. Wiss. Wien Math Naturwiss, 1923, 132(2A): 105–126.Google Scholar
- Karami, H., Experimental Investigation of Poroelastic Behaviour of a Brittle Rock. 1998, University of Lille I: Lille.Google Scholar
- Sun, P.D., Sun Model and Its Application. Hangzhou: Zhejiang University Press, 2002 (in Chinese).Google Scholar
- Sun, P.D., Xian, X.F. and Qian, Y.M., Experiment study on the effective stress in coal. Mining Safety & Environmental Protection, 1999, 2: 16–19 (in Chinese).Google Scholar
- Zhao, Y.S., Hydromechanics in Coal Rock. Beijing: China Coal Industry Publishing House, 1993 (in Chinese).Google Scholar
- Zhao, Y.S. and Hu, Y.Q., Experimental study of the law of effective stress by methane pressure. Chinese Journal of Geotechnical Engineering, 1995, 17(3): 26–31 (in Chinese).Google Scholar
- Feng, Z.C., Wu, H. and Zhao, Y.S., The numerical study of effective stresses law of rock mass. Journal of Tai Yuan University of Technology, 2003, 34(6): 713–715 (in Chinese).Google Scholar
- Zhang, Y.T., Rock Hydraulics and Engineering. Beijing: China Waterpub Press, 2005 (in Chinese).Google Scholar
- Qian, J.H. and Yin, Z.Z., Geotechnique Principle and Computing. BeiJing: China Water Power Press, 1996 (in Chinese).Google Scholar
- Yang, C.X., Evolutionary Identification of Nonlinear Material model. ShenYang: Northeastern University, 2001 (in Chinese).Google Scholar
- Lu, Y.F., Modelisation de l’endommagement anisotrope des roches saturees in laboratoire de mecanique de lille. University des Sciences et Technologies de Lille, 2002.Google Scholar