Pilot tests on vacuum preloading method combined with short and long PVDs

Sun, Liqiang; Gao, Xin; Zhuang, Daokun; Guo, Wei; Hou, Jinfang; Liu, Xiaoqiang

doi:10.1016/j.geotexmem.2017.11.010

Cited by 45 publications

(9 citation statements)

References 19 publications

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“…The flocculation-vacuum preloading method was used in these tests (Kjellman 1952;Chai and Rondonuwu 2015;Sun et al 2018;Wang et al 2019a). The purpose of these tests was No.…”

Section: Flocculation-pressure Filter Membrane Testmentioning

confidence: 99%

Performance of river sediments after flocculation-pressure filter membrane-vacuum preloading

Sun

Zheng

2020

Environ Sci Pollut Res

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The main problem in the reduction of river bottom sediments is to solve the dewatering of the sludge. The commonly used natural air drying method requires a large amount of time and economic cost. In this paper, different treatments were developed for the needs of the project, and related tests were carried out on the reduction of the sludge. Firstly, two or more flocculants were compounded according to the nature of the sludge. The 6 different treatments were determined according to the sedimentation and the turbidity value of the supernatant. Secondly, the dewatering test was carried out on river sediments after flocculationvacuum preloading. The dewatering effect of different flocculants, water quality, dissipation of pore water pressure, vane shear strength, compression coefficient, and coefficient of consolidation have been analyzed after flocculation-vacuum preloading. The polysilicate aluminium ferric (PSAF) can greatly increase the dewatering efficiency of the filter press membrane, and the final dewatering amount could reach 310 g. The effect of purifying water quality was PSAF>PAM (polyacrylamide, PAM-1(18 million): PAM-2(23 million) = 3:7)>PAC (polyaluminium chloride). The PSAF and PAC could increase the pH of the water during the vacuum preloading test. The PAM has the best the vane shear strength. Lime could improve the vacuum preloading and the vane shear strength when it was added to other flocculants. The incorporation of PSAF could accelerate the dissipation and increase the final dissipation value of pores water pressure. Compared with PAM+PAC+lime, PAM+lime, PAM+PSAF+ lime, PAM+PSAF, and PAM+PAC, the overall effect and price of the PAM is optimal.

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“…The flocculation-vacuum preloading method was used in these tests (Kjellman 1952;Chai and Rondonuwu 2015;Sun et al 2018;Wang et al 2019a). The purpose of these tests was No.…”

Section: Flocculation-pressure Filter Membrane Testmentioning

confidence: 99%

Performance of river sediments after flocculation-pressure filter membrane-vacuum preloading

Sun

Zheng

2020

Environ Sci Pollut Res

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“…Although there are alternatives undertaken and introduced by Yang et al [140], which use water as a surcharge, they are not suitable for areas with hot climates because the evaporation process will reduce the quantity of water and thus can affect the settlement monitoring readings. Besides, there are preloading methods using vacuum pressure [141,142], which only use surcharges such as minimal soil but still require soil transportation from sources elsewhere. This method is also highly costly because it involves the pumping and plastic pipes that are often exposed to leakage.…”

Section: Preloading and Prefabricated Vertical Drainsmentioning

confidence: 99%

A Review of Road Embankment Stability on Soft Ground: Problems and Future Perspective

Mamat

Kasa

Razali

2019

IIUMEJ

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This paper presents an exhaustive review of the challenges faced in the construction of road embankments on soft ground and proposes a direction for future development. Frequently used techniques for soft ground improvement are discussed. The factors that contribute to the stability of the road embankment are reviewed by approach, results of past studies, and historical cases. The findings show that settlement, slope stability, and soil bearing capacity are all challenges to constructing the road embankment. Additionally, it is found that geometric data is a key factor in embankment design. Pre-loading with prefabricated vertical drain (PVDs) methods and lightweight fill were found to be widely used techniques in soft ground improvement. The information from this study can be used to develop design guidance systems, numerical modelling, and to give an overview and knowledge to other researchers who are or will conduct research in this field. Finally, future perspectives for research are related to predictions of factors that affect the stability of road embankment with an artificial intelligence approach. ABSTRAK: Kertas ini membentangkan ulasan kajian menyeluruh mengenai cabaran yang dihadapi dalam pembinaan benteng jalanraya di atas tanah lembut dan mencadangkan ke arah pembangunan kajian masa depan. Teknik-teknik penambahbaikan tanah lembut yang sering digunakan turut dibincangkan. Faktor- faktor yang menyumbang kepada kestabilan benteng jalanraya diulas dengan pendekatan kepada kajian lepas dan sejarah kes. Hasil kajian ini didapati bahawa enapan, kestabilan cerun dan keupayaan galas tanah merupakan cabaran dalam pembinaan benteng jalanraya. Selain itu, ia didapati bahawa data geometri merupakan faktor penting kepada rekabentuk benteng. Kaedah pra pembebanan dengan prefabrikasi saliran menegak (PVDs) dan isian ringan didapati teknik yang popular digunakan dalam pembaikkan tanah lembut masa kini. Maklumat dari kajian ini boleh digunakan untuk membangunkan sistem panduan reka bentuk, pemodelan berangka serta memberi gambaran dan ilmu kepada penyelidik lain yang sedang atau akan menjalankan kajian dalam bidang ini. Akhir sekali, perspektif masa depan untuk penyelidikan berkaitan ramalan faktor-faktor yang mempengaruhi kestabilan embankment jalanraya dengan pendekatan kepintaran buatan.

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“…However, the performance of conventional vacuum preloading is not always satisfactory in every ground improvement project. Some limitations are gradually exposed with its extensive applications and such issues will lead to long consolidation time and excessive settlement after construction 7,8,9,10 . 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.…”

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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Pilot tests on vacuum preloading method combined with short and long PVDs

Cited by 45 publications

References 19 publications

Performance of river sediments after flocculation-pressure filter membrane-vacuum preloading

Performance of river sediments after flocculation-pressure filter membrane-vacuum preloading

A Review of Road Embankment Stability on Soft Ground: Problems and Future Perspective

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

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