Application of the Vacuum Preloading Method in Soil Improvement Projects

Chu, Jian; Yan, Shuwang

doi:10.1016/b978-0-08-100192-9.00004-1

Cited by 9 publications

(8 citation statements)

References 9 publications

(11 reference statements)

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“…With the depth increase, the vacuum pressure decreased, its losses observed for the depth from 0 to 0.6 m in both T1 and T2 amounted to approximately 20 kPa/m, which was consistent with the results obtained by Cai et al [22]. e depth in T1 spanning from 0.6 to 1.2 m exhibited even greater attenuation, indicating that it was impossible to achieve uniformly distributed vacuum pressure along the vertical direction in the improved soil under vacuum preloading [23,24]. e signi cant di erences between T1 and T2 included the times required to reach measurable vacuum pressure levels within the subsoil and those passed until steady pressures value were attained.…”

Section: Testing Procedure Testing Was Performed As Followssupporting

confidence: 87%

Consolidation Effect of Prefabricated Vertical Drains with Different Lengths for Soft Subsoil under Vacuum Preloading

Lou

Chai

et al. 2019

Advances in Civil Engineering

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The application of vacuum preloading to prefabricated vertical drains (PVDs) with different lengths is widely used in practical engineering to investigate their consolidation at the same depths of even and multilayer subsoils from the seabed. In a laboratory, model experiment was conducted using even subsoil and embedded PVDs with lengths of 0.6 and 1.2 m. The obtained results showed that in the even subsoil, the 1.2 m PVDs maintained a higher vacuum pressure in the shallow layer and demonstrated better consolidation behavior as compared to those of the 0.6 m PVDs. In the upper subsoil layer, the average vane shear strengths of these two systems increased to 18.2 and 22.6 kPa, respectively. The degree of consolidation of the upper subsoil layers in the two model experiments calculated from the pore water pressures under boundary drainage conditions were 51% and 68%, respectively. For practical verification purposes, similar experiments were conducted for multilayer subsoil by inserting PVDs with lengths of 6 and 15 m into different test sites. As a result, the vane shear strengths of the upper 6 m subsoil layers increased to 26.3 and 33 kPa, while the degree of consolidation were 72.1% and 80.9%, respectively, although some irregularities were observed at different depths.

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Section: Testing Procedure Testing Was Performed As Followssupporting

confidence: 87%

Consolidation Effect of Prefabricated Vertical Drains with Different Lengths for Soft Subsoil under Vacuum Preloading

Lou

Chai

et al. 2019

Advances in Civil Engineering

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“…As illustrated by Chu and Yan (2005) with the spring analogy shown in Fig. 1.1, the mechanism of the vacuum preloading is decreasing the pore pressure, rather than increasing the total stress.…”

Section: Fundamentals Of Vacuum Preloadingmentioning

confidence: 98%

Recent Advances in Soft Soil Consolidation

Indraratna

2015

Ground Improvement Case Histories

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“…This approach has been successfully used in numerous soil improvement projects across the world (Bergado et al 2002；Chu et al 2004；Chu and Yan 2005；Chu et al 2000；Holtan 1965；Seah 2006. The mechanism of vacuum preloading have been discussed extensively by many investigators, i.e., Kjellman (1952), Holtz and Wager (1975), Qian et al (1992) and Chu and Yan (2005).…”

Section: Introductionmentioning

confidence: 99%

A new method to improve the effectiveness of vacuum preloading on the consolidation of dredged fill in Wenzhou

Cai

Wang

et al. 2016

JGS Special Publication

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A new method is developed to improve the effectiveness of vacuum preloading on the consolidation of dredged fill in Wenzhou, China. This is achieved by adding some flocculants (floc) to the dredged fills while maintaining a certain level of vacuum pressure through prefabricated vertical drains (PVDs). The floc agent adopted in this study is a mixture of polyacrylamide (PAM) and calcium hydroxide (Ca(OH) 2), which would dehydrate soil particles through changing the bound water into free water. The water states transformation occurs inside the soil particles, which would significantly mitigate the risk of clogging around PVDs and enhance the soil permeability, thereby improving the efficiency of consolidation. A number of laboratory tests are conducted to testify this method. Comparison between conventional vacuum preloading method and the proposed method demonstrates that, the new method achieves better improvement of dredged fill in a shorter period of time.

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Application of the Vacuum Preloading Method in Soil Improvement Projects

Cited by 9 publications

References 9 publications

Consolidation Effect of Prefabricated Vertical Drains with Different Lengths for Soft Subsoil under Vacuum Preloading

Consolidation Effect of Prefabricated Vertical Drains with Different Lengths for Soft Subsoil under Vacuum Preloading

Recent Advances in Soft Soil Consolidation

A new method to improve the effectiveness of vacuum preloading on the consolidation of dredged fill in Wenzhou

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