Geomechanics and Engineering

  • 제24권2호
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  • Pages.129-141
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  • 2021
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  • 2005-307X(pISSN)
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  • 2092-6219(eISSN)
테크노프레스 (Techno-Press)
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DOI QR코드

DOI QR Code

Shallow ground treatment by a combined air booster and straight-line vacuum preloading method: A case study

  • Feng, Shuangxi (Department of Civil Engineering, Tianjin University) ;
  • Lei, Huayang (Department of Civil Engineering, Tianjin University) ;
  • Ding, Xiaodong (China Zhonghua Geotechnical Engineering Co., Ltd.) ;
  • Zheng, Gang (Department of Civil Engineering, Tianjin University) ;
  • Jin, Yawei (Jiangsu Xintai Geotechnical Technology Co. Ltd.)
  • 투고 : 2019.12.16
  • 심사 : 2021.01.06
  • 발행 : 2021.01.25
⟨ 이전 논문 다음 논문 ⟩

초록

The vacuum preloading method has been used in many countries for soil improvement and land reclamation. However, the treatment time is long and the improvement effect is poor for the straight-line vacuum preloading method. To alleviate such problems, a novel combined air booster and straight-line vacuum preloading method for shallow ground treatment is proposed in this study. Two types of traditional vacuum preloading and combined air booster and straight-line vacuum preloading tests were conducted and monitored in the field. In both tests, the depth of prefabricated vertical drains (PVDs) is 4.5m, the distance between PVDs is 0.8m, and the vacuum preloading time is 60 days. The prominent difference between the two methods is when the preloading time is 45 days, the injection pressure of 250 kPa is adopted for combined air booster and straight-line vacuum preloading test to inject air into the ground. Based on the monitoring data, this paper systematically studied the mechanical parameters, hydraulic conductivity, pore water pressure, settlement and subsoil bearing capacity, as determined by the vane shear strength, to demonstrate that the air-pressurizing system can improve the consolidation. The consolidation time decreased by 15 days, the pore water pressure decreased to 60.49%, and the settlement and vane shear strengths increased by 45.31% and 6.29%, respectively, at the surface. These results demonstrate the validity of the combined air booster and straight-line vacuum preloading method. Compared with the traditional vacuum preloading, the combined air booster and straight-line vacuum preloading method has better reinforcement effect. In addition, an estimation method for evaluating the average degree of consolidation and an empirical formula for evaluating the subsoil bearing capacity are proposed to assist in engineering decision making.

키워드

과제정보

The authors are grateful for the supports from financial support: National Key Research and Development Program of China (Grant No. 2017YFC0805402), National Natural Science Foundation of China (NSFC) (Grant No. 51578371), Open Project of State Key Laboratory of Disaster Reduction in Civil Engineering (Grant No. SLDRCE17-01), Incentive Fund for Overseas Visits of Doctoral Students of Tianjin University in 2019 (070-0903077101), China Scholarship Council (CSC. 201906250153).

참고문헌

  1. Artidteang, S., Bergado, D.T., Saowapakpiboon, J., Teerachaikulpanich, N. and Kumar, A. (2011), "Enhancement of efficiency of prefabricated vertical drains using surcharge, vacuum and heat preloading", Geosynth. Int., 18(1), 35-47. https://doi.org/10.1680/gein.2011.18.1.35.
  2. Basu, D., Misra, A. and Puppala, A.J. (2014), "Sustainability and geotechnical engineering: Perspectives and review", Can. Geotech. J., 52(1), 96-113. https://doi.org/10.1139/cgj-2013-0120.
  3. Bhosle, S. and Deshmukh, V. (2018), "Experimental studies on soft marine clay under combined vacuum and surcharge preloading with PVD", Int. J. Geotech. Eng., 1-10. https://doi.org/10.1080/19386362.2018.1496004.
  4. Cai, Y., Xie, Z., Wang, J., Wang, P. and Geng, X. (2018), "New approach of vacuum preloading with booster prefabricated vertical drains (PVDs) to improve deep marine clay strata", Can. Geotech. J., 55(10), 1359-1371. https://doi.org/10.1139/cgj-2017-0412.
  5. Chai, J.C., Ong, C.Y., Carter, J.P. and Bergado, D.T. (2013), "Lateral displacement under combined vacuum pressure and embankment loading", Geotechnique, 63(10), 842-856. http://doi.org/10.1680/geot.12.P.060.
  6. Chen, P. (2012), "Rapid improvement technique of shallow base in super-soft foundation", Adv. Mater. Res., 594, 401-406. https://doi.org/10.4028/www.scientific.net/AMR.594-597.401.
  7. Gouw, T. L. (2019), "Case histories on the application of vacuum preloading and geosynthetic-reinforced soil structures in Indonesia", Indian Geotech. J., 1-25. https://doi.org/10.1007/s40098-019-00391-5.
  8. Griffin, H. and O'Kelly, B.C. (2014), "Ground improvement by vacuum consolidation-a review", Proc. Inst. Civ. Eng. Ground Improv., 167(4), 274-290. https://doi.org/10.1680/grim.13.00012.
  9. Hu, J., Pan, M., Li, W., Wang, W. and Peng, J. (2018), "Field tests on marine dredger fill foundation by air-boosted vacuum preloading", Sci. Technol. Eng., 18(9), 124-129 (in Chinese).
  10. Indraratna, B., Rujikiatkamjorn, C., Ameratunga, J. and Boyle, P. (2011), "Performance and prediction of vacuum combined surcharge consolidation at Port of Brisbane", J. Geotech. Geoenviron. Eng., 137(11), 1009-1018. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000519.
  11. Khan, A.Q. and Mesri, G. (2014), "Vacuum distribution with depth in vertical drains and soil during preloading", Geomech. Eng., 6(4), 377-389. https://doi.org/10.12989/gae.2014.6.4.377.
  12. Kjellman, W. (1952), "Consolidation of clayed soils by atmospheric pressure", Proceeding of the Conference on Soil Stabilization, Cambridge, Massachusetts, U.S.A., June.
  13. Krishnapriya, P.B., Sandeep, M.N. and Antony, J. (2016), "Efficiency of vacuum preloading on consolidation behaviour of Cochin marine clay", Proceedings of the International Conference on Emerging Trends in Engineering, Science and Technology, Trissur, India, December.
  14. Kumar, S.G., Sridhar, G., Radhakrishnan, R., Robinson, R.G. and Rajagopal, K. (2015), "A case study of vacuum consolidation of soft clay deposit", Indian Geotech. J., 45(1), 51-61. https://doi.org/10.1007/s40098-014-0107-5.
  15. Lam, L.G., Bergado, D.T. and Hino, T. (2015), "PVD improvement of soft Bangkok clay with and without vacuum preloading using analytical and numerical analyses", Geotext. Geomembranes, 43(6), 547-557. https://doi.org/10.1016/j.geotexmem.2015.07.013.
  16. Lei, H., Feng, S., Wang, L. and Jin, Y. (2019), "Field instrumentation and settlement prediction of ground treated with straight-line vacuum preloading", Geomech. Eng., 19(5), 447-462. https://doi.org/10.12989/gae.2019.19.5.447.
  17. Lin, Y., Li, B. and Zhuge, A. (2016), "Application of air-boosted vacuum preloading on soft soil foundation treatment in Lianyungang", Chin. Harb. Eng., 36(11), 46-51. https://doi.org /10.7640/zggwjs201611011.
  18. Lu, Y., Chai, J. and Ding, W.Q. (2019), "Predicting deformation of pvd improved deposit under vacuum and surcharge loads", Geotext. Geomembranes, 48(1), 103502. https://doi.org/10.1016/j.geotexmem.2019.103502.
  19. Mahfouz, A.H., Ming-Jun, G. and Sharif, M. (2016), "Construction technology of modified vacuum preloading method for slurry dredged soil", Int. J. Geol. Environ. Eng., 10(2), 247-250. https://doi.org/10.5281/zenodo.1339233.
  20. Mesri, G. and Khan, A.Q. (2012), "Ground improvement using vacuum loading together with vertical drains", J. Geotech. Geoenviron. Eng., 138(6), 680-689. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000640.
  21. Ministry of Transport of the People's Republic of China. (2009), Technical specification for vacuum preloading technique to improve soft soils (JTS_147-2-2009), China Communications Press, Beijing China.
  22. Ministry of Water Resources of the People's Republic of China. (2019), Specification of soil test (GB/T 50123-2019), China Communications Press, Beijing China.
  23. Parsa-Pajouh, A., Fatahi, B., Vincent, P. and Khabbaz, H. (2014), "Analyzing consolidation data to predict smear zone characteristics induced by vertical drain installation for soft soil improvement", Geomech. Eng., 7(1), 105-131. http://doi.org/10.12989/gae.2014.7.1.105.
  24. Rujikiatkamjorn. C., Indraratna. B. and Chu. J. (2008), "2D and 3D numerical modeling of combined surcharge and vacuum preloading with vertical drains", Int. J. Geomech., 8(2), 144-156. https://doi.org/10.1061/(ASCE)1532-3641(2008)8:2(144).
  25. Sahu, R., Patra, C.R., Sivakugan, N. and Das, B.M. (2017), "Use of ANN and Neuro fuzzy model to predict bearing capacity factor of strip footing resting on reinforced sand and subjected to inclined loading", Int. J. Geosynth. Ground Eng., 3(3), 29. https://doi.org/10.1007/s40891-017-0102-x.
  26. Saowapakpiboon, J., Bergado, D.T., Voottipruex, P., Lam, L.G. and Nakakuma, K. (2011), "PVD improvement combined with surcharge and vacuum preloading including simulations", Geotext. Geomembranes, 29(1), 74-82. https://doi.org/10.1016/j.geotexmem.2010.06.008.
  27. Shen, Y., Wang, H., Tian, Y., Feng, R., Liu, J. and Wu, L. (2015), "A new approach to improve soft ground in a railway station applying air-boosted vacuum preloading", Geotech. Test. J., 38(4), 373-386. https://doi.org/10.1520/GTJ20140106.
  28. Shibata, T., Murakami, A. and Fujii, M. (2014), "Prediction of embankment behavior of regulating reservoir with foundation improved by vacuum consolidation method", Soils Found., 54(5), 938-954. https://doi.org/10.1016/j.sandf.2014.09.008.
  29. Sun, L., Gao, X., Zhuang, D., Guo, W., Hou, J. and Liu, X. (2018), "Pilot tests on vacuum preloading method combined with short and long PVDs", Geotext. Geomembranes, 46(2), 243-250. https://doi.org/10.1016/j.geotexmem.2017.11.010.
  30. Terzaghi, K. (1925), "Principles of soil mechanics, IV-settlement and consolidation of clay", Eng. News Rec., 95, 874-878.
  31. Wang, J., Cai, Y., Ma, J., Chu, J., Fu, H. and Wang, P. (2016), "Improved vacuum preloading method for consolidation of dredged clay-slurry fill", J. Geotech. Geoenviron. Eng., 142(11), 06016012. http://doi.org/10.1061/(ASCE)GT.1943-5606.0001516.
  32. Wang, J., Ma, J., Wang, P. and Fu, H. (2016), "A new method to improve the effectiveness of vacuum preloading on the consolidation of dredged fill in Wenzhou", Jap. Geotech. Soc. Sp. Publ., 2(51), 1794-1797. https://doi.org/10.3208/jgssp.TC217-05.
  33. Wu, Y., Xu, Y., Zhang, X., Lu, Y., Chen, G., Wang, X. and Song, B. (2021), "Experimental study on vacuum preloading consolidation of landfill sludge conditioned by Fenton's reagent under varying PVD filter pore sizes", Geotext. Geomembranes, 49(1), 109-121 https://doi.org/10.1016/j.geotexmem.2020.09.008.
  34. Xie, L., Niu, Y., Liu, F. and Liu, S. (2009), "Numerical analysis of vacuum drainage with air injection", Chin. J. Undergr. Sp. Eng., 5(s2),1590-1593 (in Chinese).
  35. Yanez, D.G. and Massad, F. (2018), "A case history with combined physical and vacuum preloading in Colombia", Soils Rocks, 41(2), 217-234. http:// doi.org/10.28927/SR.412217.