Case Study: Ground Improvement of Yangtze River Floodplain Soils with Combined Vacuum and Surcharge Preloading Method

Ding, Jianwen; Wan, Xing; Chongqi, Zhang; He, Zhongyi; Zhao, Lu

doi:10.1061/(asce)gm.1943-5622.0001516

Cited by 27 publications

(12 citation statements)

References 21 publications

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“…Through installing PVDs, the horizontal paths are formed, which would accelerate the consolidation of clay, especially for thick clay. Moreover, with the help of combined vacuum and surcharge preloading, higher total effective load could be attained, substantially reducing or limiting the lateral displacement, and allowing quicker construction rate 7–10 …”

Section: Introductionmentioning

confidence: 99%

Nonlinear consolidation of soft foundation improved by prefabricated vertical drains based on elliptical cylindrical equivalent model

Tian

Wen

et al. 2021

Num Anal Meth Geomechanics

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This study builds up an elliptical cylindrical equivalent model (ECEM) of prefabricated vertical drains (PVD)‐improved foundation which incorporates the nonlinear variation of compressibility and permeability and the preconsolidate state of soil. An exact solution and a simplified solution are derived for the nonlinear consolidation model under a combined vacuum and surcharge preloading. Considering the stratification of improved soil and the reduction of vacuum pressure along PVD, a precise settlement prediction method is proposed. The rightness and applicability of present solutions are verified by carrying out a series of comparative analyses. Also, a parametric study is conducted to investigate the characteristics of nonlinear consolidation under different Nσ, Cnormalc/Cnormalk, over‐consolidation ratios (OCRs). The results show that, when Cnormalc/Cnormalk=1 the applied load has no impact on the dissipation of excess pore‐water pressure, whereas a larger applied load would induce a quicker settlement rate; the consolidation rate would be underestimated if the over‐consolidated stress history is neglected, and greater OCR produces more obvious underestimation.

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Section: Introductionmentioning

confidence: 99%

Nonlinear consolidation of soft foundation improved by prefabricated vertical drains based on elliptical cylindrical equivalent model

Tian

Wen

et al. 2021

Num Anal Meth Geomechanics

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“…Many scholars have introduced the cases of soft soil treatment by vacuum preloading. The treatment time for most cases to reach the similar consolidation degree is more than 100 days, and some cases even more than 300 days (Ding et al 2019;Wu et al 2020;Indraratna et al 2011). Therefore, the consolidation efficiency of vacuum tube-well dewatering technology has obvious advantages.…”

Section: Settlement Predictionmentioning

confidence: 99%

“…At present, vacuum preloading method is one of the most popular methods for soft clay and dredger fill in coastal and riverside areas (Ding et al 2019;Griffin and O'Kelly 2014). However, vacuum preloading method takes a long time to process, and vacuum degree will attenuate along with depth, which causes its effective depth to be limited (Indraratna 2010;Chai 2005;Shen et al 2013).…”

Section: Introductionmentioning

confidence: 99%

A case study of vacuum tube-well dewatering technology for improving deep soft soil in Yangtze River floodplain

Zeng

Yu²,

Zhang

et al. 2021

Environ Earth Sci

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Deep soft soil of the Yangtze River floodplain in Nanjing has a special interlayer structure, which provides favorable conditions for the application of vacuum tube-well dewatering technology. This paper focuses on the design, construction and treatment effect of vacuum tube-well dewatering technology. The hydrological parameters and the hydraulic connections between the various layers of the site have been ascertained through two simple single-well multi-holes pumping tests. Moreover, the layout of vacuum tube-wells and depressurization wells in a test site with 84m length and 84m width was designed based on the above parameters. Field tests of vacuum tube-well dewatering technology were conducted on the test site. And the changes of groundwater level, ground settlement and pore water pressure during the test was monitored. The CPTU test technology was used to quickly evaluate the engineering properties of the site before and after treatment. Finally, combined with the settlement monitoring data, the hyperbolic method was used to predict the final settlement. The results indicated that consolidation efficiency of vacuum tube-well dewatering technology has obvious advantages. Implications of this study can provide a reference for the construction design of the site's ground improvement consolidation and other similar projects.

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“…The main reason is that the engineering characteristics of ultra-soft soil foundation are different from that of natural soft soil foundation. Past experimental and theoretical studies have demonstrated that the vacuum preloading method combined with other methods can effectively increase bearing capacity of soft soil foundations, for example, surcharge vacuum preloading technique [20][21][22][23][24], electro-osmosis vacuum preloading technique [3,25], chemical vacuum preloading technique [5,26], vacuum consolidation-compaction technique [27] and alternating vacuum preloading technique [28]. Among all these methods combined with vacuum preloading, the air-booster vacuum preloading (AVP) method is an effective improvement method for ultra-soft soil foundations [29,30].…”

Section: Introductionmentioning

confidence: 99%

Ultra-soft Ground Improvement Using Air-Booster Vacuum Preloading Method: Laboratory Model Test Study

Lei

Fang

Liu

et al. 2021

Int. J. of Geosynth. and Ground Eng.

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The air-booster vacuum preloading (AVP) method has been adopted for the treatment of ultra-soft soil foundations, especially in land reclamation projects, but the air injection mode has not yet been studied. In this paper, the authors investigated the difference in improvement effect in laboratory tests of two different air injection modes, including variable pressure and constant pressure. The results show that compared with the constant pressure AVP (CAVP) method with constant air injection pressure of 75 kPa, the variable pressure AVP (VAVP) method with variable air injection pressure from 25 to 150 kPa has a better effect on ultra-soft soil improvement. Besides, if the final air injection pressure increases properly, and the air injection pressure increases with the times of air injections slowly, the soil improvement effect is significantly improved. Compared to CAVP method, VAVP method can fully utilize the air injection effect of pressurization by forming closed spaces and enhancing permeability by crack growth.

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Case Study: Ground Improvement of Yangtze River Floodplain Soils with Combined Vacuum and Surcharge Preloading Method

Cited by 27 publications

References 21 publications

Nonlinear consolidation of soft foundation improved by prefabricated vertical drains based on elliptical cylindrical equivalent model

Nonlinear consolidation of soft foundation improved by prefabricated vertical drains based on elliptical cylindrical equivalent model

A case study of vacuum tube-well dewatering technology for improving deep soft soil in Yangtze River floodplain

Ultra-soft Ground Improvement Using Air-Booster Vacuum Preloading Method: Laboratory Model Test Study

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