Effect of Smear Zone Characteristics on PVD-Improved Soft Soils Using Field Data and Numerical Simulations

Maleki, Mohammad H.; Alielahi, Hamid; Rahmani, Iraj

doi:10.1007/s40098-022-00645-9

Cited by 3 publications

(3 citation statements)

References 44 publications

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“…6.14, SIMULIA, Dassault, France). Considering the symmetry of the numerical model [22], only half of the Lingni Seawall was modeled. The deformation of the marine soft soil ground mainly occurred in the range of the soft soil layers under the Lingni Seawall, including the muck layer with a thickness of 30 m and the mucky clay layer with a thickness of 12 m. Furthermore, previous studies [29,30] have indicated that the horizontal width of the simulation model can be set at about two times the half-width of the embankment.…”

Section: Model Scale and Boundary Conditionsmentioning

confidence: 99%

“…However, determination of the properties of the smear zone is a challenging task because of many uncertainties [20]. PVDs have usually been modeled as solid elements [21,22] in a plane-strain state [23], resulting in a large amount of calculation and a non-correspondence at the ground geometric position to the prototype model. Kan (2021) proposed a linear drain element for a PVD, representing it as a stagnant plane-strain unit cell [24].…”

Section: Introductionmentioning

confidence: 99%

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Deformation and Strength Characteristics of Marine Soft Soil Treated by Prefabricated Vertical Drain-Assisted Staged Riprap under Seawall Construction

Wu,

Liu,

Xie

2023

Buildings

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Prefabricated vertical drains (PVDs) with staged riprap preloading have been widely used in soft soil ground improvement and embankment construction. However, ground treatment effectiveness evaluation is still a difficult problem due to multiple factors. Considering this, in situ monitoring and numerical simulation were conducted to study the deformation and strength characteristics of marine soft soil ground treated by PVD-assisted staged riprap under the Lingni Seawall construction in China. Monitoring and analysis of results showed that use of PVD-assisted staged riprap resulted in a good improvement effect. In particular, in the PVD-treated zone within 10 m in depth, corresponding to a half-length of the PVD, the average radial degree of consolidation reached up to 75–100%, and the soil strength increased significantly by 200–700%. Moreover, numerical simulation showed that the linear 1-dimensional drain element of PVD closely met the engineering accuracy requirements with good consistency with the monitoring data. Compared with a totally solid element model, the numbers of elements and nodes were reduced and the calculating efficiency and model accuracy were increased by using a PVD linear element, which provides a basis for building large complex finite element models.

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Section: Model Scale and Boundary Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deformation and Strength Characteristics of Marine Soft Soil Treated by Prefabricated Vertical Drain-Assisted Staged Riprap under Seawall Construction

Wu,

Liu,

Xie

2023

Buildings

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“…In particular, proper determination of the smear zone properties of PVDs is challenging [12]. Moreover, PVD is usually modeled as a solid element in a plane-strain state [13], resulting in significant computational difficulties and a remarkable difference in the soil-PVD configuration compared to the field [14]. Therefore, developing a reliable PVD model, considering the drainage consolidation effect without increasing the finite element nodes and excluding the plane-strain equivalent transformation, is greatly needed, but not completely solved yet.…”

Section: Introductionmentioning

confidence: 99%

Settlement Forecast of Marine Soft Soil Ground Improved with Prefabricated Vertical Drain-Assisted Staged Riprap Filling

Wu,

Liu,

Alowaisy

et al. 2024

Buildings

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By comparing different settlement forecast methods, eight methods were selected considering the creep of marine soft soils in this case study, including the Hyperbolic Method (HM), Exponential Curve Method (ECM), Pearl Growth Curve Modeling (PGCM), Gompertz Growth Curve Modeling (GGCM), Grey (1, 1) Model (GM), Grey Verhulst Model (GVM), Back Propagation of Artificial Neural Network (BPANN) with Levenberg–Marquardt Algorithm (BPLM), and BPANN with Gradient Descent of Momentum and Adaptive Learning Rate (BPGD). Taking Lingni Seawall soil ground improved with prefabricated vertical drain-assisted staged riprap filling as an example, forecasts of the short-term, medium-term, long-term, and final settlements at different locations of the soft ground were performed with the eight selected methods. The forecasting values were compared with each other and with the monitored data. When relative errors were between 0 and −1%, both the forecasting accuracy and engineering safety were appropriate and reliable. It was concluded that the appropriate forecast methods were different not only due to the time periods during the settlement process, but also the locations of soft ground. Among these methods, only BPGD was appropriate for all the time periods and locations, such as at the edge of the berm, and at the center of the berm and embankment.

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Effect of smear zone on the consolidation characteristics under radial drainage

Aparna,

Robinson,

Gandhi

2024

Proceedings of the Institution of Civil Engineers - Ground Impr

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Vertical drains installed in soft clay deposits enhance the rate of consolidation in preloading projects. Using a mandrel to install the prefabricated vertical drains (PVD), its insertion and withdrawal will result in the remoulding of the soil zone surrounding it, called the smear zone. The extent of the smear zone is an important parameter that characterizes the smearing effect. This paper describes this effect in terms of smear ratio (i.e., the ratio of the diameter of smear zone ds to the diameter of drain, dw) on the consolidation characteristics of soil with radial drainage. A series of radial consolidation tests with a predetermined smear zone in a model unit cell was conducted by varying the diameter of the smear zone. The experimental results show that beyond a smear ratio of 4, the soil behaves as if it is in a fully remoulded condition. The results were compared with some of the theoretical approaches reported in the literature. The analytical solution that predicts the time-settlement curve in a better way is identified. Also, it is observed that the gain in undrained shear strength due to the consolidation of soft clay decreases with the increase in the diameter of the smear.

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Effect of Smear Zone Characteristics on PVD-Improved Soft Soils Using Field Data and Numerical Simulations

Cited by 3 publications

References 44 publications

Deformation and Strength Characteristics of Marine Soft Soil Treated by Prefabricated Vertical Drain-Assisted Staged Riprap under Seawall Construction

Deformation and Strength Characteristics of Marine Soft Soil Treated by Prefabricated Vertical Drain-Assisted Staged Riprap under Seawall Construction

Settlement Forecast of Marine Soft Soil Ground Improved with Prefabricated Vertical Drain-Assisted Staged Riprap Filling

Effect of smear zone on the consolidation characteristics under radial drainage

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