OPEN ACCESS
The problem of the reliability of capillary-barriers’ modelling is studied making use of tipping trough measurements. In its first part, the article describes laboratory measurements of saturated hydraulic conductivities and retention curves of four materials of two different capillary barriers. Both the main branches of the retention curves were measured, and the unsaturated hydraulic conductivities and capacity functions were determined. The second part of the article describes numerical modelling of two tipping trough experiments. The obtained results are compared with the measured data. The comparison shows a good agreement that is presented and discussed. It is concluded that, in the case of capillary barrier materials, the laboratory measurements made on samples and the subsequent math- ematical modelling can substitute for the tipping trough experiments.
Capillary barrier, retention curve, hydraulic characteristics, suction apparatus, hydraulic conductivity, tipping trough
[1] Ross, B., The diversion capacity of capillary barriers. Water Resources Research, 26(10), pp. 2625–2629, 1990. doi: http://dx.doi.org/10.1029/WR026i010p02625
[2] Abdolahzadeh, A.M., Vachon, B.L. & Cabral, A.R., Evaluation of the effectiveness of a cover with capillary barrier effect to control percolation into a waste disposal facility. Canadian Geotechnical Journal, 48(7), pp. 996–1009, 2011. doi: http://dx.doi.org/10.1139/t11-017
[3] Wohnlich, S., Untersuchungsbericht-Dichtigkeitsnachweis der Kombikapillardichtung (KKD). 3. Kipprinnenversuch, Bochum, 2006.
[4] Wohnlich, S. & Bitomski, K., Kombi-Kapillar-Dichtungs-Systeme zur Obelfl chenabdichtung von Deponien und Altlasten. 22. Fachtagung Die sichere Deponie, Sicherung von Deponien und Altlasten mit Kunststoffen, Wurzburg, 2006.
[5] Oldenburg, C.M. & Pruess, K., On numerical modeling of capillary barriers. Water-Resources Research, 29(4), pp. 1045–1056, 1993. doi: http://dx.doi.org/10.1029/92WR02875
[6] Webb, S.W., Generalization of Ross’ tilted capillary barrier diversion formula for different two-phase characteristic curves. Water Resources Research, 33(8), pp. 1855-1859, 1997. doi: http://dx.doi.org/10.1029/97WR01231
[7] Trpkosova, D. & Mls, J., The infl uence of artifi cial sealing on the capillary barrier’s function. Waste Management, 30(1), pp. 125–131, 2010. doi: http://dx.doi.org/10.1016/j.wasman.2009.09.029
[8] Morris, C.E. & Stormont, J.C., Evaluation of numerical simulations of capillary barrier field tests. Geotechnical and Geological Engineering, 16, pp. 201–213, 1998. doi: http://dx.doi.org/10.1023/A:1008853710339
[9] Trpkosova, D. & Mls, J., Effi ciency of capillary barriers in relation to retention curves data. Acta Geodynamica et Geomaterialia, 7(2), pp. 201–207, 2010.
[10] Trpkosova, D. & Mls, J., Hydraulic characteristics of capillary barrier in relation to its efficiency. Acta Hydrologica Slovaca, 9(2), pp. 170–178, 2008. (in Czech).
[11] Powers, M.C., A new roundness scale for sedimentary particles. Journal of Sedimentary Research, 23(2), pp. 117–119, 1953.
[12] Havllcek, J. & Myslivec, A., The Infl uence of Saturation and Stratifi cation on the Shearing Properties of Certain Soils. In Proceedings 6th Int. Conf. Soil and Mech. Found. Engineering, 1, pp. 235-239. University of Toronto Press, 1965.
[13] Kuraz, V., Kucerova, A. & Kuraz, M., The use of genetic algorithms for retentioncurves approximation. In Proceedings of the Conference Days of Soil Physics, Velke Bilovice, 2003. (in Czech).
[14] van Genuchten, M.T., A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44(5), pp. 892–898, 1980. doi: http://dx.doi.org/10.2136/sssaj1980.03615995004400050002x
[15] van Genuchten, M.T., Leu, F.J. & Yates, S.R., The RETC Code for Quantifying the Hydraulic Functions of Unsaturated Soils, EPA: California, 1991.
[16] Mualem, Y., New model for predicting hydraulic conductivity of unsaturated porousmedia. Water Resources Research, 12(3), pp. 513–522, 1976. doi: http://dx.doi.org/10.1029/WR012i003p00513
[17] Vogel, T., Documentation of the S2D Code - Version 2.0, CTU Praha, 1999. (internal).
[18] Mls, J., Description of the M.GS.vOl code. UK Praha, 2002. (in Czech, unpublished).