Geomechanics and Engineering

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Field instrumentation and settlement prediction of ground treated with straight-line vacuum preloading

  • Lei, Huayang (Department of Civil Engineering, Tianjin University) ;
  • Feng, Shuangxi (Department of Civil Engineering, Tianjin University) ;
  • Wang, Lei (Department of Civil Engineering, Tianjin University) ;
  • Jin, Yawei (Jiangsu Xintai Geotechnical Technology Co. Ltd)
  • Received : 2018.07.31
  • Accepted : 2019.11.28
  • Published : 2019.12.10
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Abstract

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

Keywords

Acknowledgement

Supported by : National Natural Science Foundation of China (NSFC), Tianjin University, China Scholarship Council (CSC)

The authors acknowledge the National Key Research and Development Program of China (Grant No. 2017YFC0805402), the National Natural Science Foundation of China (NSFC) (Grant No. 51578371), the Open Project of State Key Laboratory of Disaster Reduction in Civil Engineering (Grant No. SLDRCE17-01), the Tianjin Construction Commission Science and Technology Project (Grant No. 2017E6-0015), Incentive Fund for Overseas Visits of Doctoral Students of Tianjin University in 2019 (070-0903077101), and China Scholarship Council (CSC. 201906250153) for their financial support.

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