A new technique for hydraulic conductivity testing of expansive unsaturated soils

• Autorzy: Zakowicz S. , Garbulewski K.

Warianty tytułu

PL

Nowa technika badań przewodności hydraulicznej nienasyconych gleb pęczniejących

• Języki publikacji: EN

Abstrakty

EN

A number of factors are known to influence the hydraulic conductivity (K) of soils. While a large number of laboratory and field methods have been developed over the years, most of them are applicable mainly for the measurement of hydraulic properties in saturated soils. Moreover, those methods omit such factors affecting hydraulic conductivity as soil volume changes (swelling or shrinkage) and external load simulating the location of the soil tested. The purpose of this paper is to present direct and simple methods for estimation of hydraulic properties, mainly conductivity of unsaturated soils. The methods proposed are based on evaluation of soil-water potential and water outflow from a soil sample. The test methods allow the 1- and 3-dimensional stress states of the soil and pore-fluid to be monitored. The procedure allows also to monitor the changing soil moisture using the TDR technique. The modified apparatus (triaxial apparatus, consolidometer and tempe pressure cell), soils and procedures are described first, and then the results of tests are presented and reviewed. Interpretation of test results is made using the Multi-step method. Results obtained showed that the stress states simulating the location of soil affected the hydraulic parameters significantly. The test results confirmed the usefulness of the methods proposed for testing the porous medium with the geometrical changes of soil (swelling/shrinkage) considered.

PL

Duża ilość czynników ma wpływ na przewodność hydrauliczną gleb nienasyconych. Do głównych możemy zaliczyć: wielkość i rozkład porów, wilgotność, gradient hydrauliczny, właściwości fizyczno-chemiczne cieczy biorącej udział w przepływie oraz stopień nasycenia gleby. Pomimo, że dotychczas stosuje się różne laboratoryjne metody przewodności hydraulicznej to większość z nich przystosowana jest do badań przewodności hydraulicznej gleb nasyconych. Ponadto stosowane metodyki nie uwzględniają takich czynników jak zmiany geometrii gleby (pęcznienie/skurczalność) i zewnętrzne obciążenie symulujące położenie gleby w profilu. W artykule przedstawiono metody określania przewodności hydraulicznej w pęczniejących nienasyconych glebach. Metody te oparte są na określeniu potencjału wody glebowej, objętości wypływającej wody z próbki i kontroli zmian uwilgotnienia metoda reflektometryczna (TDR). Interpretacja wyników badań oparta jest na metodzie Multi-step zaproponowanej przez Echinga i Hopmansa.

Słowa kluczowe

EN

TDR technique; new technique; hydraulic conductivity; unsaturated soil zone; soil

• Wydawca: -
• Czasopismo: Zeszyty Problemowe Postępów Nauk Rolniczych
• Rocznik: 1996
• Tom: 436
• Opis fizyczny: p.183-191,fig.,ref.

Twórcy

autor

Zakowicz S.

• Faculty of Land Reclamation and Environmental Engineering, Warsaw Agricultural University, Nowoursynowska 166, 02-787 Warsaw, Poland

autor

Garbulewski K.

• Faculty of Land Reclamation and Environmental Engineering, Warsaw Agricultural University, Nowoursynowska 166, 02-787 Warsaw, Poland

Bibliografia

• 1. Aitchison G. D., Richards B. G.: Fundamental mechanisms involved in soil moisture movement and the engineering properties of soils which are important in such movements. Proc. 2nd. Inti. Conf. on Expansive Clay Soils, Texas A & M Univ., Texas, 1969, 66 - 84.
• 2. Bishop A. W.: The principle of effective stress. Teknisk Ukeblad, vol. 106, no. 39, 859 - 86, 1953.
• 3. Chandler R. J., Crully M. S., Montgomery-Smith G.: A low-cost method of assessing clay desiccation for low-rise buldings. Proc.Instn. Civ. Engrs Civ. Engng, 92, May, 82 - 89, Paper 9767, 1992.
• 4. Domżal H.: Soil condensation effect on the content of strongly bounded water and on the retention of productive and available water (in Polish). An. Soil Sci., 30(3), 45 - 72 Warsaw, 1979.
• 5. Eching S. O., Hopmans J. W.: Inverse solution of unsaturated soil. Hydraulic functions from transient outflow and soil water pressure data. Land, Air and Water Resources Paper 100021, University of California, 1993.
• 6. Fredlund D. C.: Stress state variables for unsaturated soils. Proc. ASCE, 103 (GT5), 447 - 466, 1977.
• 7. Fredlund D. G.: Appropriate concepts and technology for unsaturated soils. Canadian Geotech. J., 16, 121 - 139, 1979.
• 8. Garbulewski K., Wolski W., Żakowicz S., Al-Hello K.: Expansive behaviour of unsaturated fine-grained soils in compacted canal embankments. Proc. of the Conference “Engineered fills”, Newcastle upon Tyne, Thomas Telford, 130 - 139, 1993.
• 9. Garbulewski K., Żakowicz S.: Suction as an indicator of soil expansive potential. Proc. of the First Int. Conference on Unsaturated Soils. Paris, 2: 593 - 599, 1995.
• 10. Garbulewski K., Żakowicz S., Al-Hello: Expansion potential of compacted fine-grained soils using suction measurements. Geotechnical Testing J., GTJODJ, 17(4), 505 - 510, 1994.
• 11. Klute A.: Methods of Soil Analysis. 2nd Edition, Madison USA, 1986.
• 12. Malicki M. A.: A reflectometric (TDR) meter of moisture content in soil (in Polish). Problemy Agrofizyki, 64 ,95 - 101, 1991.
• 13. Malicki M. A.: Influence of soil physical properties on electrical parameters of electrodes/soil system in aspect of the determination of soil moisture and salinity (in Polish). Acta Agrophysica, Lublin, 1993.
• 14. Malicki M. A., Skierucha W. M.: A manually controlled TDR soil moisture meter operating with 300 ps rise-time needle pulse. Irrigation Science, 10, 153 - 163, 1989.
• 15. Philip J. R., Smlles D. E.: Kinetics of sorption and volume change in 3 - component systems. Aust. J. Soil Res., 7, 1 - 19, 1969.
• 16. Richards B. G.: Modelling interactive load -deformation and flow processes in soils, including unsaturated and swelling soils. Proc. 6th Aust-NZ Conference on Geotechnics, 18 - 37, 1992.
• 17. Richards B. G., Horn R., Baumgartl Th., Graesle W.: The role of stress on the behaviour of unsaturated soils. Proc. First Int. Conference on Unsaturated Soils. Paris, vol. 2, 785 - 790, 1995.
• 18. Van Genuchten M. Th., Leij F. J., Yates S. R.: The RETC code for quantifying the hydraulic functions of unsaturated soils. EPA/600/2 - 91/065, U. S. Salinity Laboratory, Riverside, California, 1991.
• 19. Wang X., Benson C. H.: Infiltration and saturated hydraulic conductivity of comapcted clay. J. Geotech. Eng. Vol. 121, 10, 713 - 722, 1995.
• 20. Żakowicz S., Garbulewski K.: Modification of triaxial apparatus for predetion of dam core behaviour. Proc. of the First Int. Conference on Unsaturated Soils. Paris, vol. 2, 585 - 590, 1995.