Sains Malaysiana 45(1)(2016): 141–156

New Progress in the Study of Intergranular Suction and Shear Strength of Unsaturated Soil

(Kemajuan Baharu dalam Kajian Sedutan Bebutir dan Kekuatan Ricih daripada

 Tanah Tak Tepu)

LIANSHENG TANG¹*, HAITAO SANG^2,3, LIQUN JIANG¹ & YINLEI SUN¹

¹School of Earth Sciences and Geological Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275 China

²School of Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275, China

³Guangdong Province Key Laboratory of Geological Processes and Mineral Resources Guangzhou, Guangdong 510275, China

Received: 11 July 2014/Accepted: 15 November 2014

ABSTRACT

The suction between soil particles is the basis and core problem in the study of unsaturated soil. However, is the suction between soil particles just the matrix suction (which has been widely used since the discipline of unsaturated soil mechanics was established). In fact, the concept of matrix suction is from soil science and reflects the water-absorbing capacity of the soil. Matrix suction characterizes the interaction between soil particles and pore water rather than the interactions between soil particles, which were not in conformity with the principle of effective stress of soils. The suction of unsaturated soil, in essence, is the intergranular suction composed of absorbed suction and structural suction. In this paper, first, the basic concepts of absorbed suction and structural suction were briefly introduced. Then, with soil mechanics, powder science, crystal chemistry, granular material mechanics and other related disciplines of knowledge for reference, the quantitative calculation formulas were theoretically deduced for the absorbed suction for equal-sized and unequal-sized unsaturated soil particles with arbitrary packing and the variable structural suction for equal-sized unsaturated soil particles with arbitrary packing and unequal-sized unsaturated soil particles with close tetrahedral packing. The factors that influence these equations were discussed. Then, the shear strength theory of unsaturated soil was established based on the theory of intergranular suction through the analysis of the effective stress principle of unsaturated soil. This study demonstrates that the shear strength of unsaturated soil consists of three parts: The effective cohesive force, the additional strength caused by external loads and the strength caused by intergranular suction. The contribution of the three parts to the shear strength of unsaturated soil depends on the following influence factors: Soil type, confining pressure, water content and density. Therefore, these factors must be comprehensively considered when determining the strength of an unsaturated soil.

Keywords: Absorbed suction; intergranular suction; shear strength; structural suction; unsaturated soil

ABSTRAK

Sedutan antara zarah tanah adalah asas dan teras masalah dalam kajian tanah tidak tepu. Walau bagaimanapun, adakah sedutan di antara zarah tanah hanya sedutan matrik (yang telah digunakan secara meluas sejak disiplin mekanik tanah tak tepu ditubuhkan). Malah, konsep matriks sedutan adalah daripada sains tanah dan mencerminkan keupayaan menyerap air daripada tanah. Matriks sedutan menyifatkan interaksi antara zarah tanah dan air liang daripada interaksi antara zarah tanah yang tidak selaras dengan prinsip tegasan berkesan tanah. Sedutan tanah tak tepu, pada dasarnya, adalah sedutan bebutir terdiri daripada sedutan diserap dan sedutan struktur. Dalam kertas ini, pertama, konsep asas sedutan diserap dan sedutan struktur telah diperkenalkan secara ringkas. Kemudian, dengan mekanik tanah, sains serbuk, kimia kristal, mekanik bahan berbutir dan disiplin lain yang berkaitan pengetahuan untuk rujukan, formula pengiraan secara teori kuantitatif telah disimpulkan untuk sedutan diserap untuk sama bersaiz dan tidak sama rata bersaiz zarah tanah tepu dengan sewenang-wenangnya dan pembungkusan sedutan struktur tanah tak tepu yang berubah-ubah dan yang sama bersaiz zarah dengan pembungkusan sembarangan dan saiz zarah tanah tepu tidak sama rata dengan pembungkusan tertrahedron tertutup. Faktor yang mempengaruhi persamaan ini telah dibincangkan. Kemudian, teori kekuatan ricih tanah tidak tepu ditubuhkan berdasarkan teori sedutan bebutir melalui analisis prinsip tegasan berkesan tanah tidak tepu. Kajian ini menunjukkan bahawa kekuatan ricih tanah tidak tepu mengandungi tiga bahagian: Daya padu efektif, kekuatan tambahan disebabkan oleh beban luaran dan kekuatan yang disebabkan oleh sedutan bebutir. Sumbangan daripada tiga bahagian untuk kekuatan ricih tanah tidak tepu bergantung kepada faktor pengaruh berikut: Jenis tanah, tekanan mengurung, kandungan air dan ketumpatan. Oleh itu, faktor-faktor ini perlu dipertimbangkan secara menyeluruh apabila menentukan kekuatan tanah yang tidak tepu.

Kata kunci: Kekuatan ricih; sedutan bebutir; sedutan struktur; serap sedutan; tanah tak tepu

REFERENCES

Ashraf, M.A., Ullah, S., Ahmad, I., Qureshi, A.K., Balkhair, K.S. & Rehman, M.A. 2013. Green biocides, a promising technology: Current and future applications. Journal of the Science of Food and Agriculture 94(3): 388-403.

Baker, R. & Frydman, S. 2009. Unsaturated soil mechanics, critical review of physical foundations. Engineering Geology 106: 26-39.

Batool, S., Khalid, A., Chowdury, A.J.K., Sarfraz, M., Balkhair, K.S. & Ashraf, M.A. 2015. Impacts of azo dye on ammonium oxidation process and ammonia oxidizing soil bacteria. RSC Advances 5: 34812-34820.

Diamonds, S. 1970. Pore size distributions in clays. Clays and Clay Minerals 18: 723-724.

Gens, A. 2010. Soil-environment interactions in geotechnical engineering. Geotechnique 60: 3-74.

He, W., Zhao, M.H., Chen, Y.G. & Wang, H.H. 2010. Theoretical study of microscopical mechanisms and computational method of hysteresis in SWCCs. Rock and Soil Mechanics 31: 1078-1083.

Ibrahim, A., Mukhlisin, M. & Jaafar, O. 2014. Rainfall infiltration through unsaturated layered soil column. Sains Malaysiana 43(10): 1477-1484.

Jia, Q.J., Zhao, C.G. & Han, Z.D. 2005. Study on shear strength of the unsaturated soils in pendular state and its application. Rock and Soil Mechanics 26: 580-585.

Kim, T.H. & Hwang, C. 2003. Modeling of tensile strength on moist granular earth material at low water content. Engineering Geology 69: 233-244.

Lian, G.P., Thornton, C. & Adams, M.J. 1993. A theoretical study of the liquid bridge forces between two rigid spherical bodies. Journal of Colloid Interface Science 161: 138-147.

Lu, N. & Likos, W.J. 2006. Suction stress characteristic curve for unsaturated soils. Journal of Geotechnical and Geoenviromental Engineering 132: 131-142.

Luan, M.T., Li, S.Q. & Yang, Q. 2006. Matric suction and tension suction of unsaturated soils. Chinese Journal of Geotechnical Engineering 28: 863-868.

Meng, L.M. 2013. Tention atmosphere general formulas of effective stress principle of unsaturated soil. The World of Building Materials 34: 38-43.

Miao, T.D., Mu, Q.S., Liu, Z.Y. & Ma, C.W. 2001. Effective stress and shear strength of unsaturated soil with low water content. Chinese Journal of Geotechnical Engineering 23: 393-396.

Mitchell, J.K. & Soga, K. 2005. Fundamentals of Soil Behavior. 3rd ed. New Jersey: John Wiley & Sons, Inc.

Mu, Q.S., Ma, C.W. & Miao, T.D. 2004. Research on shear strength of unsaturated sand with low-moisture content. Chinese Journal of Geotechnical Engineering 26: 674-678.

Qureshi, T., Memon, N., Memon, S.Q. & Ashraf, M.A. 2015. Decontamination of ofloxacin: Optimization of removal process onto sawdust using response surface methodology. Desalination and Water Treatment 57(1): 221-229.

Ran, L.Z., Song, X.D. & Tang, C.S.D. 2011. Laboratorial investigation on tensile strength of expansive soil during drying. Journal of Engineering Geology 19: 620-625.

Shen, Z.J. 1996a. Retrospect and prospect of unsaturated soil mechanics. Advances in Science and Technology of Water Resources 161: 1-5.

Shen, Z.J. 1996b. Generalized suction and unified deformation theory for unsaturated soils. Chinese Journal of Geotechnical Engineering 18: 1-9.

Shen, C.N., Fang, X.W., Wang, H.W., Sun, S.G. & Guo, J.F. 2009. Research on effects of suction, water content and dry density on shear strength of remolded. unsaturated soils. Rock and Soil Mechanics 30: 1347-1351.

Shimada, K., Fujii, H.S., Nishiyama, T. & Morii, T. 2000. Change of shear strength due to interfacial tensions and matric suction of pore water in unsaturated sandy soil. Proceedings of Unsaturated Soils for Asia, edited by Balkema, A.A. pp.147-152.

Surhio, M.A., Talpur, F.N., Nizamani, S.M., Amin, F., Bong, C.W., Lee, C.W., Ashraf, M.A. & Shahid, M.R. 2014. Complete degradation of dimethyl phthalate by biochemical cooperation of the Bacillus thuringiensis strain isolated from cotton field soil. RSC Advances 4: 55960-55966.

Tang, L.S. 2000a. Structure suction and principle of general effective stress in unsaturated soils. ACTA Scientiarum Naturalium Universitatis Sunyatseni 39: 95-100.

Tang, L.S. 2000b. Mechanical effect of chemical action of water on soil and analysis on its mechanism. ACTA Scientiarum Naturalium Universitatis Sunyatseni 39: 104-109.

Tang, L.S. & Wang, S.J. 2006. Absorbed suction and principle of effective stress in unsaturated soils. Chinese Journal of Geotechnical Engineering 22: 83-88.

Tang, L.S., Sang, H.T., Song, J., Liu, F.T., Yan, B. & Zhang, P.C. 2013. Research on soil particle joint function and brittle-elastoplastic cement damage model of unsaturated granite residual soil. Rock and Soil Mechanics 34: 1453-1457.

Tang, L.S., Yan, B., Zhang, P.C. & Zhang, Q.H. 2006. Definition and exploration for effective stress and related conception in unsaturated soil. Chinese Journal of Geotechnical Engineering 28: 216-220.

Terzaghi, K. 1943. Theoretical Soil Mechanics. New York: Wiley Inc.

Wang, M. 1987. The interaction between water and clay particles in saturated clayey soils. Hydrogeology and Engineering Geology 13: 1-5.

Willet, C.D., Adams, M.J., Johnson, S.A. & Sevile, J.P.K. 2003. Effects of wetting hysteresis on pendular liquid bridges between rigid spheres. Powder Technology 130: 63-69.

Willett, C.D., Adams, M.J. & Johnson, S.A. 2000. Capillary bridges between two spherical particles. Langmuir 16: 9396-9405.

Xing, Y.C., Wu, P.A. & Luo, Y.S. 1996. Triaxial test on undisturbed unsaturated loess. Journal of Hydraulic Engineering 1: 47-52.

Yin, Z.Y., Zhao, J.D. & Hicher, P.Y. 2014. A micromechanics-based model for sand-silt mixtures. International Journal of Solids and Structures 51: 1350-1363.

Yin, Z.Y., Chang, C.S. & Hicher, P.Y. 2010. Micromechanical modelling for effect of inherent anisotropy on cyclic behavior of sand. International Journal of Solids and Structures 47: 1933-1951.

Yoshitaka, K. & Oka, C. 2012. Growth of liquid bridge in AFM. Journal of Colloid and Interface Science 40: 4368-4375.

Zhang, Z., Liu, F.Y. & Zhang, G.P. 2013. A physical hysteresis boundary water retention model for uniform wet particulate material. Journal of Hydraulic Engineering 44: 1165-1174.

Zhang, Z., Liu, F.Y., Zhang, G.P. & Zheng, F. 2007. Microscopic hydraulic behavior from the interactions between uneven-sized wet particles and liquid bridge. Journal of Hydraulic Engineering 28: 1323-1327.

Zhang, B.J., Yang, J.Q. & Ding, J.X. 2006. The effect of mineral component grain composition on CBR value. Soil Engineering and Foundation 20: 85-87.

Zhao, M.H., Liu, X.P. & Peng, W.X. 2007. Application of aqueous film theory to study of unsaturated soil’s suction. Rock and Soil Mechanics 44: 810-817.

Zhao, C.G., Li, J., Liu, Y., Cai, G.Q. & Asreazad, S. 2013. Discussion on some fundamental problems in unsaturated soil mechanics. Rock and Soil Mechanics 34: 1825-1831.

Zulkifley, M.T.M., Ng, N.T., Abdullah, W.H., Raj, J.K., Ghani, A.A., Shuib, M.K. & Ashraf, M.A. 2014a. Geochemical characteristics of a tropical lowland peat dome in the Kota Samarahan-Asajaya area, West Sarawak, Malaysia. Environmental Earth Sciences 73(4): 1443-1458.

Zulkifley, M.T.M., Fatt, N.T., Raj, J.K., Hashim, R. & Ashraf, M.A. 2014b. The effects of lateral variation in vegetation and basin dome shape on a tropical lowland stabilization in the Kota Samarahan-Asajaya area, West Sarawak, Malaysia. Acta Geologica Sinica 88(3): 894-914.

*Corresponding author; email: eestls@mail.sysu.edu.cn