Abstract
Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel (CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage (permeable CFG pile bodies) and the later stage (impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors (including the replacement rate m, the treatment depth h 1, the permeability coefficient K s1, K v2 and compression modulus E s1, E s2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.
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References
SCHIFFMAN R L, STEN J R. One-dimensional consolidation of layered systems [J]. Journal of Soil Mechanics & Foundations Div, ASCE, 1970, 96(4): 1499–1504.
LEE P K K, XIE K H, CHEUNG Y K. A study on one-dimensional consolidation of layered systems [J]. International Journal for Numerical and Analytical Methods in Geomechanics, 1992, 16(11): 815–831.
WANG G C. Consolidation of soft clay foundations reinforced by stone columns under time-dependent loadings [J]. Geotech Geoenvironment Eng, ASCE, 2009, 135(12): 1922–1931.
XIE K H, LU M M, HU A F, CHEN G H. A general theoretical solution for the consolidation of a composite foundation [J]. Comput Geotech, 2009, 36(12): 24–30.
LU M M, XIE K H, GUO B. Consolidation theory for a composite foundation considering radial and vertical flows within the column and the variation of soil permeability within the disturbed soil zone [J]. Can Geotechl J, 2010, 47(2): 207–217.
LU M M, XIE K H, WANG S Y, LI C X. Analytical solution for the consolidation of a composite foundation reinforced by an impervious column with an arbitrary stress increment [J]. Int J Geomech ASCE, 2013, 13(1): 33–40.
MIAO L, WANG X, KAVAZANJIAN J E. Consolidation of a double-layered compressible foundation partially penetrated by deep mixed columns [J]. J Geotech Geoenviron Eng, ASCE, 2008, 134(8): 1210–1214.
CASTRO J, SAGASETA C. Consolidation around stone columns: Influence of column deformation [J]. Int J Numer Anal Met, 2009, 33(7): 851–877.
TAO Y, JIN Z Y, JING N. Analytical solution for the consolidation of a composite ground reinforced by partially penetrated impervious columns [J]. Computers and Geotechnics, 2014, 57: 30–36.
JI Tong-yuan, HU Yin-bao, LIU Song-yu, ZHU Xiang-yang. Excess pore pressure induced by single CFG pile driven into soft ground [J]. Journal of Highway and Transportation Research and Development, 2004, 21(3): 18–21. (in Chinese)
XU Zhi-jun, WANG Shu-guang. Cement fly-ash gravel piles composite foundation [M]. 3rd ed. Beijing: China Machine Press, 2004: 1–16. (in Chinese)
ZHAO Ming-hua, LIU Qin, ZOU Xin-jun. Consolidation analysis of composite ground with cement fly-ash gravel piles [J]. Journal of Hunan University, 2007, 34(9): 1-5. (in Chinese)
JI Shu-peng, TANG Tong-zhi, ZHAN Yun-gang. Consolidation regularity study of composite ground with cement fly-ash gravel piles [J]. Subgrade Engineering, 2006 (4): 28–31. (in Chinese)
TANG Tong-zhi, ZHAO Wei-bing. Ground consolidation analysis for before & after the solidification of CFG pile treated soft clay foundation of expressway [C]// Expressway Ground Treatment and Practice-Nationwide Expressway Ground Treatment Academic Seminar. Guangzhou, China; China Communications Press, 2005: 422–427. (in Chinese)
JGJ 79-2012. Technical code for ground treatment of buildings [S]. 2012-08-23.
QIAN Jia-huan, YIN Zong-ze. Soil principle and calculation [M]. 2nd ed. Beijing: China Hydraulic and Hydroelectric Press, 2006: 199–258. (in Chinese)
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Foundation item: Project(51378197) supported by the National Natural Science Foundation of China
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Zou, Xj., Zhao, Zm. & Xu, Db. Consolidation analysis of composite foundation with partially penetrated cement fly-ash gravel (CFG) piles under changing permeable boundary conditions. J. Cent. South Univ. 22, 4019–4026 (2015). https://doi.org/10.1007/s11771-015-2945-4
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DOI: https://doi.org/10.1007/s11771-015-2945-4