Abstract
Pore fluid pressures that develop within soil masses as a result of both mechanical and physico-chemical effects influence the magnitude of the intergranular or effective stresses. The intergranular stresses control, in many cases, soil behavior in shear and compression. The physical significance of pore water pressure in a cohesive soil is examined in terms of several components which combine to give the total pressure. An analysis of fluid pressures at various points within a soil mass based on a condition of no flow at equilibrium shows that changes in any one component of the total pressure from point to point are offset by changes in other components.
The analysis shows that a pore pressure measurement reflects interparticle repulsive pressures and water adsorptive forces as well as purely hydrostatic pressures arising from mechanical effects. The individual components of total pore pressure are not directly measurable except in special systems. Data are presented which indicate that a significant portion of the swell of a compacted soil is attributable to water pressure deficiencies caused by mechanical and capillary components which act in addition to osmotic pressure components.
Component water pressures are related to stresses between particles. It is shown that intergranular pressures are dependent on osmotic and adsorptive components of the total water pressure.
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References
Aitchison, G. D. (1960) Relationship of moisture stress and effective stress functions in unsaturated soils. Proc. Conference on Pore Pressures and Suction in Soils: Butterworths, London, pp. 18–23.
Baver, L. D. (1956) Soil Physics: John Wiley & Sons, Inc., New York, 3rd ed., 489 pp.
Bishop, A. W. (1960a) The measurement of pore pressure in the triaxial test. Proc. Conference on Pore Pressure and Suction in Soils: Butterworths, London, pp. 52–60.
Bishop, A. W. (1960b) The principle of effective stress: Norwegian Geotechnical Institute, Oslo, Pub. 32, pp. 1–5.
Bishop, A. W. (1960c) Factors controlling the strength of partially saturated cohesive soils. Proc. ASCE Research Conference on the Shear Strength of Cohesive Soils: Boulder, Colorado. In press.
Bishop, A. W. and Eldin, G. (1950) Undrained triaxial tests on saturated soils and their significance in the general theory of shear strength: Geotechnique, v. 2, pp. 13–32.
Bolt, G. H. (1955) Analysis of the validity of the Gouy—Chapman theory of the electric double layer: J. Colloid Sci., v. 10, p. 206.
Bolt, G. H. (1956) Physical-chemical analysis of the compressibility of pure clay: Geotechnique, v. 6, no. 2, pp. 86–93.
Bolt, G. H. and Frissel, M. J. (1960) Thermodynamics of soil moisture: Netherlands J. Agr. Sci., v. 8, no. 1, pp. 57–78.
Bolt, G. H. and Miller, R. D. (1955) Compression studies of illite suspensions: Soil Sci. Soc. Amer. Proc., v. 19, pp. 285–288.
Bolt, G. H. and Miller, R. D. (1958) Calculation of total component potentials of water in soil: Trans. Amer. Geophys. Un., v. 39, no. 5, pp. 917–928.
Croney, D. and Coleman, J. D. (1953) Soil moisture suction properties and their bearing on the moisture distribution in soils: Proc. 3rd Int. Conf. on Soil Mech. and Found. Eng., v. 1, pp. 13–18.
Edlefson, N. E. and Anderson, A. B. (1943) Thermodynamics of soil moisture: Hilgardia, v. 15, pp. 31–298.
Hilf, J. W. (1956) An investigation of pore water pressures in compacted cohesive soils: U.S. Bureau of Reclamation, Denver, Colorado, Tech. Memorandum 654, 109 pp.
Jennings, J. E. (1960) A revised effective stress law for use in the prediction of the behavior of unsaturated soils. Proc. Conference on Pore Pressures and Suction in Soils: Butterworths, London, pp. 24–28.
Ladd, C. C. (1959) Mechanisms of swelling by compacted clay: Highway Research Board Bull. 245, pp. 10–26.
Lambe, T. W. (1960) A mechanistic picture of shear strength in clay. Proc. ASCE Research Conference on Shear Strength of Cohesive Soils: Boulder, Colorado. In press.
Lambe, T. W. (1961) Residual pore pressures in compacted clay: in 5th Int. Conf. of Soil Mech. and Found. Eng., Paris, July 1961.
Lambe, T. W. and Whitman, R. V. (1959) The role of effective stress in the behavior of expansive soils: Proc. 1st Annual Colorado Soil Mechanics Conference, pp. 33–66.
Low, P. F. (1958) Movement and equilibrium of water in soil systems as effected by soil-water forces: Highway Research Board, Special Report 40, pp. 55–64.
Low, P. F. (1959) Discussion to “Physical—Chemical properties of soils: Ion exchange phenomena,” by Taylor, A. W.: Amer. Soc. Civil Engineers, Proc., paper 2010, pp. 79–89.
Low, P. F. and Deming, J. H. (1953) Movement and equilibrium of water in heterogeneous systems with special reference to soils: Soil Sci., v. 75, pp. 187–202.
Marsal, R. J. and Resines, J. S. (1960) Pore pressure and volumetric measurements in shear tests. Proc. ASCE Research Conference on the Shear Strength of Cohesive Soils: Boulder, Colorado. In press.
Marshall, T. J. (1959) Relations between water and soil; Com. Bureau Soils Tech. Comm. No. 50, C.A.B. Hartenden, 91 pp.
Mitchell, J. K. (1960) The application of colloidal theory to the compressibility of clays. Proc. Seminar on Interparticle Forces in Clay-Water-Electrolyte Systems: Commonwealth Scientific and Industrial Research Organization, Melbourne, pp. 2.92–2.97.
Rosenqvist, I. Th. (1959) Physico-chemical properties of soils: Soil—water systems: Amer. Soc. Civil Engineers, Proc., paper 2000, pp. 31–53.
Seed, H. B. and Chan, C. K. (1959) Structure and strength characteristics of compacted clays: Amer. Soc. Civil Engineers Proc., paper 2216, pp. 87–128.
Seed, H. B., Mitchell, J. K. and Chan, C. K. (1960) The strength of compacted cohesive soils: Proc. A.S.C.E. Research Conf. on Shear Strength of Cohesive Soils: Boulder, Colorado. In press.
Terzaghi, K. (1925) Erdbaumechanik auf Bodenphysikalischer Grundlage: Dueticke, Wein, 399 pp.
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Mitchell, J.K. Components of Pore Water Pressure and their Engineering Significance. Clays Clay Miner. 9, 162–184 (1960). https://doi.org/10.1346/CCMN.1960.0090109
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DOI: https://doi.org/10.1346/CCMN.1960.0090109