Mechanism of pore water seepage in soil reinforced by step vacuum preloading

Shan, Wenchong; Chen, Huie; Yuan, Xiaoyan; Ma, Wenliang; Li, Hui

doi:10.1007/s10064-020-02075-4

Cited by 18 publications

(9 citation statements)

References 29 publications

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“…Considering the physical and mechanical properties, e.g., the average pore ratio and clay (d < 0.005 mm) content, of dredged mud slurry can vary by different geographical locations and different compositions, a dimensionless index, the cumulative rate R e of the average void ratio as the main evaluation index, and the clay content as the auxiliary index have been introduced as the double control indexes for judging the stability of the batch sedimentation. The cumulative rate R e of the average void ratio can be conveyed by Equation (10).…”

Section: −=mentioning

confidence: 99%

“…∑ ∆e i e 0 = e 0 − e stable e 0 (10) where ∆e i is the void ratio increment per period, e 0 is the void ratio before the batch sedimentation happens, and e stable is the average void ratio of the sediment when the batch sedimentation stabilized. The curves of the cumulative change rate R e of the average pore ratio of samples from group I Nansha and group II Huizhou during the batch sedimentation are given in Figure 11, while the data of a study in Tianjin Binhai New Area [39] are also included.…”

Section: R E =mentioning

confidence: 99%

“…During this consolidation process, external loads can be applied on the soil skeletons and force out the pore water within them; with the drainage of the pore water, the soil will become denser, and its effective stress will increase. Ideally, to ensure a better treatment effect, a foundation reinforcement method, such as the vacuum preloading method (VPM), should be employed at this stage [10]. Otherwise, the vacuum pressure applied to the sediments may carry the suspended soil particles away along with the water and cause a clogging phenomenon [11] near the drains.…”

Section: Introductionmentioning

confidence: 99%

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Batch Settling and Low-Pressure Consolidation Behaviors of Dredged Mud Slurry: Steady-State Evaluation and Mechanism Study

Bao,

Guo,

Dong

et al. 2023

Water

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Since the exploration of the characteristics of dredged mud slurry during batch settlement and low-pressure consolidation (less than 100 kPa) is still insufficient, the determination of the optimal time to start the vacuum preloading method (VPM) on dredged-fill foundations is still empirically oriented (due to a lack of enough scientific basis). To further explore the characteristics of dredged mud slurry during batch settlement and low-pressure consolidation, samples from typical dredged-fill land projects were obtained and used to conduct batch sedimentation model experiments and low-pressure (less than 100 kPa) consolidation tests. The results of experiments and analyses showed the following: (1) the clay (d < 0.005 mm) content is a main factor affecting the batch settlement and consolidation characteristics of dredged mud slurry, which is not conducive to the consolidation effect of dredged-fill foundations. (2) For dredged mud slurry whose clay content is within 40% to 60%, the cumulative change rate of the average porosity ratio of 60% to 75% is suitable for evaluating the steady state of its batch sedimentation process, i.e., the optimal starting time of VPM. Finally, based on the experimental analyses, a settlement prediction method that considers both the batch sedimentation and the low-pressure consolidation processes was developed and validated.

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Section: −=mentioning

confidence: 99%

Section: R E =mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Batch Settling and Low-Pressure Consolidation Behaviors of Dredged Mud Slurry: Steady-State Evaluation and Mechanism Study

Bao,

Guo,

Dong

et al. 2023

Water

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“…Vertical wells usually have large influence depths. Vacuum pressure has been applied to vertical wells to achieve a rapid consolidation of soil in soil improvement projects [21][22][23][24]. The application of vacuum pressure generates negative pore pressures along the soil surface and along the length of a vertical well.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Model Tests of Leachate Drawdown Using Vertical Drainage Wells with Vacuum Pumping in Municipal Solid Waste Landfills with High Leachate Levels

Ni³

et al. 2022

Sustainability

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Municipal solid waste (MSW) landfills in China generally have high leachate mounds, which potentially induce severe geotechnical and environmental issues. In this study, laboratory model tests were carried out to preliminarily investigate the performance of vertical drainage wells accompanied with vacuum pumping (VDW-VP) on leachate drawdown in MSW landfills with high leachate levels. Leachate drawdown tests through VDW-VP under conditions with and without gas injection were performed. Different vacuum pressures (0~−9.5 kPa) were imposed during the tests. Results indicated that the leachate pumping processes for both the two conditions were characterized by a stage of continuous effluent followed by a stage of discontinuous effluent, corresponding to the periods before and after the leachate level in the vertical well dropped to the bottom, respectively. During the stage of continuous effluent, as the vacuum pressure increased, the effluent rate decreased and the leachate level in the vertical well needed a longer time to reach the bottom. During the stage of discontinuous effluent, the leachate level in the MSW gradually approached that in the vertical well. A higher vacuum pressure rendered a larger cumulative leachate pumping volume for the condition with a gas injection, but this was not the case for the condition without a gas injection. In addition, some local pore water pressures were observed to suddenly increase and drop under the condition with the gas injection, attributed to the migration of entrapped gas zones. The increase in vacuum pressure might promote the migration of entrapped gas zones and hence increase the cumulative leachate pumping volume.

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“…The core construction method is to shallowly strengthen the extremely low-strength muddy soil through foundation treatment (Xu et al, 2019;Dong et al, 2011), and partly use fly ash (Sani et al, 2018;Karthik et al, 2014;Takhelmayum et al, 2013) and soil-fly ash-lime (Consoli et al, 2014) for reinforcement, thereby forming a hard shell layer and improving the bearing capacity of foundation. Judging from the existing research (Shan et al, 2021;Huang et al, 2010;Kuna et al, 2016), the shallow reinforcement technology of muddy soil can be achieved by natural drying, sand-filled cushion, shallow soil drainage, and chemical reinforcement. The in-situ solidification method with solidifying agent can greatly reduce the cost and construction period, help to recycle industrial waste materials, and save the cost of spoiled land acquisition during the construction process and the cost of earthwork transportation, which is a new hot spot in the research of shallow reinforcement of muddy soil.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Triaxial Test and Microscopic Study of Solidified Muddy Soil With Different Mixing Ratios and Curing Ages

Zhou

Cheng

et al. 2021

Front. Mater.

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Aiming to explore the optimal mixture ratio and curing age of solidified muddy soil under dynamic load, the paper intends to investigate whether the solidified muddy soil can be used as filling of high-speed railway subgrade. Based on the dynamic triaxial test, the investigation measured the dynamic strain and dynamic elastic modulus of solidified muddy soil under different mix ratios and curing ages, and also observed the microscopic morphology of solidified muddy soil samples by using scanning electron microscope. The results show that the addition of cement and curing agent significantly increases the dynamic strength and elastic modulus of muddy soil, which effectively improve the dynamic characteristics of muddy soil. The curing effect of the curing agent is more obvious with the increase of the dosage of cement and curing agent under different mix ratio. The content of curing agent plays a leading role in the hydration reaction between cement, curing agent and soil particles. Additionally, in case of the same test conditions, when the ratio of cement mass to dry silt mass is 1:20, the ratio of diluent volume to dry silt mass is 1:20, with 28 days of curing age, its curing effect will reach the best.

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Mechanism of pore water seepage in soil reinforced by step vacuum preloading

Cited by 18 publications

References 29 publications

Batch Settling and Low-Pressure Consolidation Behaviors of Dredged Mud Slurry: Steady-State Evaluation and Mechanism Study

Batch Settling and Low-Pressure Consolidation Behaviors of Dredged Mud Slurry: Steady-State Evaluation and Mechanism Study

Laboratory Model Tests of Leachate Drawdown Using Vertical Drainage Wells with Vacuum Pumping in Municipal Solid Waste Landfills with High Leachate Levels

Dynamic Triaxial Test and Microscopic Study of Solidified Muddy Soil With Different Mixing Ratios and Curing Ages

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