Mineralogy, Micro-fabric and the Behavior of the Completely Decomposed Granite Soils
The main objective of this study is to investigate the impact of the micro-fabric and soil mineralogy on the overall macro-behavior of the completely decomposed granite soil through a set of drained and undrained triaxial shearing and isotropic compression tests on a medium-coarse grading completely decomposed granite soil. The mineral composition of the soil was a substantial factor governing the compressive behavior. The soil compressibility increased significantly in the case of existence crushable and weak minerals within the soil minerals like fragile feldspar, as well as the high content of fines, especially the plastic fines. The scanning electron microscopic photos indicated that the micro-fabric of the soil had a paramount impact on the compressive behavior. The mechanism of the volumetric change depended on the stress levels, the soil mineral composition and the grain morphology. In the low consolidated stress levels, the soils’ grains rearrangement was the prevailing mechanism of the volumetric change, particularly with the absence of weak and crushable minerals. On the other hand, at the high consolidated stress levels, particles’ crushing was the prevailing mechanism in the volumetric change. Both the mechanisms of volume change could occur simultaneously at the low stress levels in the case of presence crushable minerals in addition to micro-cracks in the soil grains. The soil showed an isotropic response after 250 kPa, as this stress level erased the induced anisotropy from the moist tamping preparation method. Under the drained shearing conditions, the soil showed a contractive response, while during the undrained shearing conditions, the soil exhibited both the contractive and dilative responses with phase transformation points. The studied soil showed a unique critical state line, irrespective of the drainage conditions and initial states, the critical state line was parallel to the isotropic compression line in the void ratio effective stress space. In the deviator effective mean stresses space, the studied soil approached a unique CSL with a critical stress ratio equal 1.5, corresponding to critical friction angle of 36.8°.
Ng, C. W. W., P. Guan, and Y. J. Shang. “Weathering Mechanisms and Indices of the Igneous Rocks of Hong Kong.” Quarterly Journal of Engineering Geology and Hydrogeology 34, no. 2 (May 2001): 133–151. doi:10.1144/qjegh.34.2.133.
Rocchi, I., and M. R. Coop. “Mechanisms of Compression in Well-Graded Saprolitic Soils.” Bulletin of Engineering Geology and the Environment 75, no. 4 (January 2, 2016): 1727–1739. doi:10.1007/s10064-015-0841-7.
Chiu, C.F., and Charles W.W. Ng. “Relationships Between Chemical Weathering Indices and Physical and Mechanical Properties of Decomposed Granite.” Engineering Geology 179 (September 2014): 76–89. doi:10.1016/j.enggeo.2014.06.021.
Irfan, T. Y. “Mineralogy, Fabric Properties and Classification of Weathered Granites in Hong Kong.” Quarterly Journal of Engineering Geology and Hydrogeology 29, no. 1 (February 1996): 5–35. doi:10.1144/gsl.qjegh.1996.029.p1.02.
Lumb, Peter. “The Properties of Decomposed Granite.” Géotechnique 12, no. 3 (September 1962): 226–243. doi:10.1680/geot.19184.108.40.206.
Vaughan, P., M. Maccarini, and S. Mokhtar, Indexing the engineering properties of residual soil. Quarterly Journal of Engineering Geology and Hydrogeology, 1988. 21(1): p. 69-84.
Rocchi, Irene, M. C. Todisco, and Matthew R. Coop. "Influence of grading and mineralogy on the behaviour of saprolites." In Proc. 6th Int. Symp. on Deformation Characteristics of Geomaterials, IS-Buenos Aires, Argentina, pp. 415-422. 2015.
Ham, Tae-Gew, Yukio Nakata, Rolando P. Orense, and Masayuki Hyodo. “Influence of Gravel on the Compression Characteristics of Decomposed Granite Soil.” Journal of Geotechnical and Geoenvironmental Engineering 136, no. 11 (November 2010): 1574–1577. doi:10.1061/(asce)gt.1943-5606.0000370.
Ham, Tae-Gew, Yukio Nakata, Rolando Orense, and Masayuki Hyodo. “Influence of Water on the Compression Behavior of Decomposed Granite Soil.” Journal of Geotechnical and Geoenvironmental Engineering 136, no. 5 (May 2010): 697–705. doi:10.1061/(asce)gt.1943-5606.0000274.
Lee, I. K., and M. R. Coop. “The Intrinsic Behaviour of a Decomposed Granite Soil.” Géotechnique 45, no. 1 (March 1995): 117–130. doi:10.1680/geot.19220.127.116.11.
Ng, Charles WW, W. T. Fung, C. Y. Cheuk, and Liming Zhang. "Influence of stress ratio and stress path on behavior of loose decomposed granite." Journal of Geotechnical and Geoenvironmental Engineering 130, no. 1 (2004): 36-44. doi:10.1061/(ASCE)1090-0241(2004)130:1(36).
Yan, W.M., and X.S. Li. “Mechanical Response of a Medium-Fine-Grained Decomposed Granite in Hong Kong.” Engineering Geology 129–130 (March 2012): 1–8. doi:10.1016/j.enggeo.2011.12.013.
Wang, Y. H., and W. M. Yan. "Laboratory studies of two common saprolitic soils in Hong Kong." Journal of geotechnical and geoenvironmental engineering 132, no. 7 (2006): 923-930. doi:10.1061/(ASCE)1090-0241(2006)132:7(923).
Elkamhawy, Elsayed, Bo Zhou, and Huabin Wang. “Transitional Behavior in Well-Graded Soils: An Example of Completely Decomposed Granite.” Engineering Geology 253 (April 2019): 240–250. doi:10.1016/j.enggeo.2019.02.027.
Ietto, Fabio, Francesco Perri, and Federico Cella. “Weathering Characterization for Landslides Modeling in Granitoid Rock Masses of the Capo Vaticano Promontory (Calabria, Italy).” Landslides 15, no. 1 (July 13, 2017): 43–62. doi:10.1007/s10346-017-0860-5.
Elkamhawy, Elsayed, Huabin Wang, Bo Zhou, and Zhiyong Yang. “Failure Mechanism of a Slope with a Thin Soft Band Triggered by Intensive Rainfall.” Environmental Earth Sciences 77, no. 9 (May 2018). doi:10.1007/s12665-018-7538-8.
GEO, Geoguide 3—Guide to Rock and Soil Descriptions. Geotechnical Engineering Office, Civil Engineering Department, The Government of the Hong Kong Special Administrative Region. 2017.
Alavi Nezhad Khalil Abad, S.V., A. Tugrul, C. Gokceoglu, and D. Jahed Armaghani. “Characteristics of Weathering Zones of Granitic Rocks in Malaysia for Geotechnical Engineering Design.” Engineering Geology 200 (January 2016): 94–103. doi:10.1016/j.enggeo.2015.12.006.
Ng, Charles WW, and Abraham CF Chiu. "Behavior of a loosely compacted unsaturated volcanic soil." Journal of Geotechnical and Geoenvironmental Engineering 127, no. 12 (2001): 1027-1036. doi:10.1061/(ASCE)1090-0241(2001)127:12(1027).
Zauyah, Siti, Carlos E.G.R. Schaefer, and Felipe N.B. Simas. “Saprolites.” Interpretation of Micromorphological Features of Soils and Regoliths (2010): 49–68. doi:10.1016/b978-0-444-53156-8.00004-0.
Skempton, A. W. “The Pore-Pressure CoefficientsAandB.” Géotechnique 4, no. 4 (December 1954): 143–147. doi:10.1680/geot.1918.104.22.168.
Head, K.H., in Manual of soil laboratory testing. 1992, Vol. 3. John Wiley and Sons: New York.
Verdugo, R. and K. Ishihara, The steady state of sandy soils. Soils and Foundations, 1996. 36(2): p. 81-91.
Lee, Jong-Sub, Maria Guimaraes, and J. Carlos Santamarina. "Micaceous sands: Microscale mechanisms and macroscale response." Journal of Geotechnical and Geoenvironmental Engineering 133, no. 9 (2007): 1136-1143. doi:10.1061/(ASCE)1090-0241(2007)133:9(1136).
Zhou, B., and J. Wang. “Random Generation of Natural Sand Assembly Using Micro x-Ray Tomography and Spherical Harmonics.” Géotechnique Letters 5, no. 1 (January 2015): 6–11. doi:10.1680/geolett.14.00082.
Ham, Tae-Gew, Yukio Nakata, Rolando Orense, and Masayuki Hyodo. “Strength Anisotropy of Compacted Decomposed Granite Soils.” Geotechnical and Geological Engineering 30, no. 1 (September 22, 2011): 119–127. doi:10.1007/s10706-011-9454-5.
Ng, Charles WW, and Abraham CF Chiu. "Laboratory study of loose saturated and unsaturated decomposed granitic soil." Journal of Geotechnical and Geoenvironmental Engineering 129, no. 6 (2003): 550-559. doi:10.1061/(ASCE)1090-0241(2003)129:6(550).
Been, Ken, and Mike G. Jefferies. "A state parameter for sands." Géotechnique 35, no. 2 (1985): 99-112.
- There are currently no refbacks.
Copyright (c) 2019 Elsayed Elkamhawy, Bo Zhou, huabin Wang
This work is licensed under a Creative Commons Attribution 4.0 International License.