Ground deformation induced by vacuum loading–unloading

Wu, Yajun; Xu, Fang; Mei, Yuan; Li, Jingpei

doi:10.1007/s12665-015-4915-4

Cited by 18 publications

(4 citation statements)

References 15 publications

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“…For the fill SPM, ground heave was observed as the surcharge was being unloaded. 14,15 Similar ground heave was also found during vacuum removal by Wu et al 4 However, some measured results proposed by Indraratna et al 9 and Kianfar et al 16 showed that ground settlement rather than heave occurred during the vacuum removal. According to the measured results from Indraratna et al, 9 when the vacuum pressure decreased from 80 to 0 kPa, the settlement increased from 20.1 to 21.5 mm, as shown in Figure 1.…”

Section: Introductionsupporting

confidence: 60%

“…[1][2][3] In order to minimize these hazards, vacuum preloading method (VPM) has been extensively applied to enhance the modulus and strength of clayey soils. [4][5][6] Generally, the VPM does not necessarily require surcharge fill, however, it requires a geomembrane to seal the underlying clayey soil. Under the geomembrane the vacuum pressure could reach about 80 kPa by means of vacuum pumps.…”

Section: Introductionmentioning

confidence: 99%

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RETRACTED: Mechanism analysis on ground settlement induced by vacuum removal

Liu

Liang

Chen

et al. 2019

International Journal of Electrical Engineering & Education

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Due to the settlement hazards induced by the soft clayey soils, vacuum preloading has been widely used all over the world. Many studies focus on the process of vacuum application but the process of vacuum removal is generally ignored. Different from observations on surcharge preloading, ground settlement rather than heave occurred during vacuum removal. In this study, a stress-controlled triaxial test was carried out to simulate both processes of vacuum application and removal applied on a clayey soil and hence the mechanism of ground settlement induced by vacuum removal is discussed. Compressive axial strain was observed during the decrease of isotropic stress that simulated vacuum removal. To better understand the observed deformation characteristics of the clayey soils during vacuum removal, in this study, a simple anisotropic elastic model was used. The happening of ground settlement of the clayey soil during vacuum removal is mainly because that the Young’s modulus in the vertical direction is higher than that in the horizontal direction. Lateral extension is dominant for the ground deformation during vacuum removal.

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Section: Introductionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

RETRACTED: Mechanism analysis on ground settlement induced by vacuum removal

Liu

Liang

Chen

et al. 2019

International Journal of Electrical Engineering & Education

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“…Peng et al [10] and Bao et al [11] conducted field tests to study pore water pressure transfer properties and distribution model of negative pressure. Shen et al [12] and Wu et al [13] proposed the calculation of consolidation settlement and increased soil strength through vacuum preloading according to the Mohr-Coulomb's failure criterion and the vacuum preloading field test. Sun et al [14] proposed a membraneless vacuum preloading method and carried out a field test.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Vacuum Preloading for Reinforcing Soil inside Composite Bucket Foundation for Offshore Wind Turbines

Ding

Peng

Zhang

et al. 2019

JMSE

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The composite bucket foundation (CBF) with seven honeycomb subdivisions is a new foundation for offshore wind turbine structures. The bearing capacity of CBF can be improved by consolidation of soil inside the CBF, which is caused by the vacuum preloading method after installation. A three-dimensional numerical model is established to simulate the consolidation process of soil for CBF with and without subdivisions in terms of vertical settlement, pore water pressure and void ratio of the soil. This analysis investigates the reinforcement effect of the two foundation types to assess the influence of the bulkheads. The results obtained show that there are obvious reinforcement effects for both foundation types. In the early stage of consolidation, vertical settlement is rapid, and this becomes stable with time. The depth at which the pore water pressure becomes negative is the depth showing the main reinforcement. Vacuum pressure decreases continuously with increase in soil depth and time. In addition, the excess pore water pressure in the soil dissipates, which turns into the soil effective stress. Bulkheads provide vertical drainage channels in the soil and shorten the seepage path, allowing the extraction of more pore water. This is conducive to the improvement of shallow soil, while also decreasing the extraction of pore water in deep soil and the region of the soil that can be reinforced.

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“…Indraratna et al [15] proposed an equivalent 2D numerical modelling to analyse PVD-assisted soft ground consolidation, and the performance of the model provided a good agreement between the numerical and analytical predictions, as well as the field measurements. Ya et al [16] proposed a method to calculate the ground settlement and the lateral displacement induced by vacuum preloading and analysed two well-documented field cases in China. Ye et al [8] used the field test and numerical analysis method to study the performance of PVD-reinforced soft soil with surcharge preloading and vacuum preloading.…”

Section: Introductionmentioning

confidence: 99%

Influence of PVD-Enhancing Soft Soil Ground on the Adjacent Bridge Piles – A 3d Fem Analysis

Wei

Feng

et al. 2018

CEJ

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The influence of prefabricated vertical drain (PVD)-enhancing soft soil on the adjacent bridge pile foundation is not sufficiently clear. The related studies are scarce and far behind the requirement of engineering practice. Three-dimensional finite element model (3D FEM) is established to investigate this important issue. Plastic drainage boards in the PVD are modelled by a user-defined element, which considers the axial force and permeability of the plastic drainage board, whereas its weight, shear, and torsion are not considered. The elastoplastic-consolidation coupled model is used for the soils. Field measured results of pore water pressure, ground settlement, and pile cap displacement are used to validate the 3D FEM with good accuracy. A number of useful conclusions can provide guidelines for similar projects and inform designers of the adverse effects of PVD-enhancing soft soil ground on the adjacent bridge pile foundation.

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Ground deformation induced by vacuum loading–unloading

Cited by 18 publications

References 15 publications

RETRACTED: Mechanism analysis on ground settlement induced by vacuum removal

RETRACTED: Mechanism analysis on ground settlement induced by vacuum removal

Numerical Simulation of Vacuum Preloading for Reinforcing Soil inside Composite Bucket Foundation for Offshore Wind Turbines

Influence of PVD-Enhancing Soft Soil Ground on the Adjacent Bridge Piles – A 3d Fem Analysis

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