New Vacuum-Preloading Technique for Ultrasoft-Soil Foundations Using Model Tests

Lei, Huayang; Qi, Ziyang; Zhang, Zhipeng; Zheng, Gang

doi:10.1061/(asce)gm.1943-5622.0000934

Cited by 36 publications

(7 citation statements)

References 30 publications

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“…When using the conventional vacuum preloading technique to consolidate the newly pumped dredged clay, there is often a reduction in drainage capacity due to the clogging of the filter sleeves of PVDs. A multiple-step vacuum applied method has been investigated in recent years through laboratory model tests [25][26][27] and field cases [28,29]. The vacuum pressure could be applied in two-step of 40 and 80 kPa, in three-step of 20, 40, and 80 kPa, and even in five-step of 10, 20, 40, 60, and 80 kPa [29].…”

Section: Multiple-step Vacuum Preloadingmentioning

confidence: 99%

Recent Developments in the Vacuum Preloading Technique in China

et al. 2022

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A series of studies have confirmed that vacuum preloading can effectively accelerate the consolidation process of soft soil. In recent years, further improvement in the efficiency of this method is still the continuing goal of scholars. This paper reviews the recent improvements in the vacuum preloading techniques as well as their practical applications in China. The advantages and disadvantages of each method are discussed. It is found that replacing or eliminating one or more components of the vacuum preloading system, such as sand-free, membrane-free, horizontal drain, multiple-step, and air booster vacuum preloading methods, achieved similar soil improvement effects to those of the traditional vacuum preloading method. Vacuum preloading combined with other soil improvement methods could improve the soil with the lower average water content and the higher average shear strength.

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Section: Multiple-step Vacuum Preloadingmentioning

confidence: 99%

Recent Developments in the Vacuum Preloading Technique in China

et al. 2022

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“…First of all, the vacuum pressure dissipates with time and depth, such situation will not only result in ineffective consolidation of deep soil, but lower vacuum pressure can also lead to a longer construction period. What's more, the performance of prefabricated vertical drains (PVDs) in drainage can be adversely affected by clogging since the dredged slurry is the main fill material for land reclamation projects 11,12 . Fine clay particles would accumulate at the filter membrane of the PVDs inevitably as consolidation proceeds, which results in a significant decrease in the permeability of PVDs 13 .…”

Section: Introductionmentioning

confidence: 99%

“…What's more, the performance of prefabricated vertical drains (PVDs) in drainage can be adversely affected by clogging since the dredged slurry is the main fill material for land reclamation projects. 11,12 Fine clay particles would accumulate at the filter membrane of the PVDs inevitably as consolidation proceeds, which results in a significant decrease in the permeability of PVDs. 13 The clogging effect can even stop the consolidation process despite extended construction time, which would also result in insufficient consolidation of the ground.…”

Section: Introductionmentioning

confidence: 99%

Analytical solutions for consolidation of soft soil improved by air‐boosted vacuum preloading considering clogging effect

Sun

2023

Num Anal Meth Geomechanics

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Air‐boosted vacuum preloading is a newly emerging soft soil‐improving technology and increasingly draws attention of researchers and engineers. However, few analytical theories are available in the literature to facilitate the design and calculation of it in practice. To fill this gap, an analytical model for the consolidation of soft ground improved by air‐boosted vacuum preloading is proposed based on the assumption of equal volumetric strain and Darcy's law. Moreover, a time‐dependent clogging effect is taken into consideration to describe the gradual reduction in the drainage capacity of prefabricated vertical drains (PVDs) during the consolidation process. In addition, the smear effect is also considered due to the installation of PVDs. An air booster pipe and the surrounding PVDs are introduced into the unit cell for analysis based on the principle of equal cross‐sectional area, and analytical solutions under two typical time‐dependent horizontal loading are then developed. A comparison is made with the existing analytical model of conventional vacuum consolidation, which indicates that air‐boosted vacuum preloading can promote the consolidation of soft soil more effectively than conventional vacuum preloading. Furthermore, the obtained solution under instantaneously loading is used to investigate the influence of several parameters on consolidation behavior. Finally, to verify the accuracy of the analytical model with or without clogging effect, a comparative study is carried out with a field test.

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“…The AVP method removes sand cushion generated by the conventional method and adopts a pressurizing system to accelerate the dissipation of pore water pressure [31,32]. Many factors affect the consolidation of the AVP method, such as pressurized conditions, pressurized timing, and pressurized duration.…”

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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New Vacuum-Preloading Technique for Ultrasoft-Soil Foundations Using Model Tests

Cited by 36 publications

References 30 publications

Recent Developments in the Vacuum Preloading Technique in China

Recent Developments in the Vacuum Preloading Technique in China

Analytical solutions for consolidation of soft soil improved by air‐boosted vacuum preloading considering clogging effect

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

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