Jun CAI, Jingtao ZHANG, Guangyin DU, Han XIA

Application of the Dynamic Compaction Method for Ground Improvement of Collapsible Loess in Qinhai

The collapsibility of loess has a great influence on subgrade construction in Qinghai, China, so laboratory tests are utilized to evaluate the collapsibility influencing factors, which illustrates that the collapsibility of this region is not dominated by soluble salts but an alkaline environment, high porosity and a low water content. The in situ self-weight submerging test reveals the settlement regularities, with a maximum settlement of 22.4 cm, which suggests that the soil in the test region is self-weight collapsible loess. In consideration of the economy and applicability, dynamic compaction was chosen as the ground improvement method. The optimal number of drops (N) for an energy level of 1000 kN·m is 6, and for the energy levels of 1500 kN·m and 2000 kN·m, N is 8. Besides the maximum effective depth for 1000 kN·m is 5 – 6 m, and it is 6 – 7 m for 1500 kN·m and 2000 kN·m.

Anahtar Kelimeler:

Loess, collapsibility, ground treatment, dynamic compaction

Application of the Dynamic Compaction Method for Ground Improvement of Collapsible Loess in Qinhai

Keywords:

Loess, collapsibility, ground treatment, dynamic compaction,

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[1] Qian H. X, Luo Y. S. Collapsible loess subsoil. Beijing: China Architecture & Building Press, 1985.
[2] Yao Z. H., Huang X. F., Chen Z. H., Zhang J. H., Comprehensive submerging tests on self-weight collapse loess with heavy section in Lanzhou region. Chinese Journal of Geotechnical Engineering, 1(34):65 – 74, 2012.
[3] Liu Z. D, Mechanics and engineering of loess. Xi'an: Shanxi Sciences and Technology Press, 1996.
[4] Chen Z. H., Xu Z. H., Liu Z. D., Some problems of collapsed loess. Chinese Journal of civil Engineering, 19(3):62 – 69, 1986.
[5] Shao S. J., Yang C. M., Ma X. T. et al, Correlation analysis of collapsible parameters and independent physical indices of loess. Rock and Soil Mechanics, 34 Supp(2): 27 - 34, 2013.
[6] Gao G. R., A structure theory for collapsing deformation of loess soils. Chinese Journal of Geotechnical Engineering, 12(4): 1 – 10, 1990.
[7] Kovacs, J; Raucsik, B, Varga, A., et al, Clay mineralogy of red clay deposits from the central Carpathian Basin (Hungary): implications for Plio-Pleistocene chemical weathering and palaeoclimate. Turkish Journal of Earth Sciences, (22): 414 – 426, 2013.
[8] Walsh K., Houston W., Houston S. L., Evaluation of in-place witting using soil suction measurement. Geotechnical Engineering, 119(5):862 – 873, 1993.
[9] Miao T. D., Liu Z. Y., Ren J. S., Deformation mechanism and constitutive relation of collapsed loess. Chinese Journal of Geotechnical Engineering, 21(4):383 – 387, 1999.
[10] Liao S. X., Study on pre-submerging of collapsible loess. Nonferrous Metallurgy Construction, 3(2): 1 – 13, 1983.
[11] Qian H. J., Zhu M., Xie S., Experimental study on the regularities of collapsible deformation of loess foundation in Hejin, Shanxi. Chinese Journal of Geotechnical Engineering, 14(6): 1 – 9, 1992.
[12] Li D. Z., He Y. H., Sui G. X., Study and test on immersion of Q2 loess in large area. Chinese Journal of Geotechnical Engineering, 15(2): 1 – 11, 1993.
[13] Houston S. L., Foundations and pavements on unsaturated soils. Proceeding 1st International Conference on Unsaturated Soils, Paris, France, 1995.
[14] Huang X. F., Chen Z. H., Ha S., Xue S. G., Sun S. X., Xu Y. M., Jin X. J., Zhu Y. Q., Large area field immersion test on characteristics of deformation of self-weight collapse loess under overburden pressure. Chinese Journal of Geotechnical Engineering, 28(3): 382 – 389, 2006.
[15] Lyu X. J., Gong X. N., Li J. G., Research on parameters of construction with dynamic compaction method. Rock and Soil Mechanics, 27(9): 1628 – 1633, 2006.
[16] Xing Y. D., Wang C. M., Zhang L. X., Effect analysis of dynamic ramming for collapsible loess roadbed in west of Liaoning. Journal of Liaoning Technical University (Natural Science), 27(3): 371 – 373, 2008.
[17] Zhan J. L., Shui W. H., Application of high energy level dynamic compaction to ground improvement of collapsible loess for petrochemical project. Rock and Soil Mechanics, 30(S2): 469 – 472, 2009.
[18] Huang X. F., Chen Z. H., Fang X. W., Zhu Y. Q., Guo J. F., Wei X. F., Study on foundation treatment thickness and treatment method for collapse loess with large thickness. Chinese Journal of Rock Mechanics and Engineering, 26(S2): 4332 – 4338, 2007.
[19] Hu C. M., Mei Y., Wang X. Y., Experimental research on dynamic compaction parameters of collapsible loess foundation in Lishi region. Rock and Soil Mechanics, 33(10):2903 – 2909, 2012.
[20] Code for building construction in collapsible loess regions, GB/ 50025-2004, China Architecture and Building Press
[21] Mitchell J. J., Kenichi S., Fundamentals of soil behavior. John Wiley & Sons Inc, Hoboken, New Jersey, 2005.
[22] Xie D. Y., Xing Y. C., Soil Mechanics for Loess Soils. Beijing: Higher Education Press, 2016.
[23] Liu Z. D., Li J., Guo Z. Y., Rao W. Y., Deformation behaviours and deformation parameter of loess in Shanxi district. Chinese Journal of Geotechnical Engineering, 6(3): 24 – 34, 1984.
[24] Lin Y., Study on engineering characteristics of deep layer collapsible loess in Pengjiaping area of Lanzhou City, Lanzhou University, 2019
[25] Wang J. Q., Lei S. Y., Li X. L., Wang Y. M., Liu Z., Wang X. G., Correlation of wet collapsibility coefficient and physical property parameters of loess. Coal Geology and Exploration, 41(3): 42 – 50, 2013.
[26] Huang X. F., Yang X. H., A study progress on in-situ soaking test on collapsible loess. Rock and Soil Mechanics, 34(S2): 222 – 228, 2013.
[27] Xu Z. J., Zhang Y. N., Dynamic compaction and dynamic compaction replacement methods for reinforcing foundation. Beijing: China Machine Press, 2004.
[28] Technical code for ground treatment of buildings. Ministry of Housing and Urban-Rural Development of the People’s Republic of China. 2012, (JGJ 79-2012).
[29] Lukas R. G., Delayed soil improvement after dynamic compaction. Ground Improvement, Ground Reinforcement, Ground Treatment. Published by the ASCE, 1997: 409 – 420, 1997.