Abstract
Discharge capacity is one of the important factors affecting the consolidation behavior of vertical drains (VDs). Both previous experimental tests and field behavior indicated that the discharge capacity of VDs usually decreased with an increase in effective stress. The aim of this study is to develop a nonlinear analytical solution for consolidation analysis of VD-installed soft deposits considering a reduction of discharge capacity, in which a nonlinear distribution of VD’s discharge capacity with depth is adopted. To verify this work, the proposed solution is compared with previous solutions. The analyzed results show that at a given time and depth, the consolidation rate in the case of discharge capacity with a nonlinear distribution is lower than that of a linear and constant distribution. The proposed solution is then applied to a real embankment on the VD-installed thick soft ground in Busan New Port. It is shown that the proposed solution using the nonlinear distribution of VD discharge capacity provides a good agreement with the field data.
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Abbreviations
- A, A 1, A 2 :
-
Constants
- C c :
-
Compression index
- Ch :
-
Coefficient of horizontal consolidation (m2/s)
- \(\bar{C}_{h}\) :
-
Average coefficient of horizontal consolidation (m2/s)
- d e :
-
Diameter of unit cell (m)
- d s :
-
Diameter of the smear zone (m)
- d w :
-
Diameter of the drain (m)
- e :
-
Void ratio
- e o :
-
Initial void ratio
- H :
-
Thickness of soft clay layer (m)
- H 1 and H 2 :
-
Thickness of soft clay layer (m)
- k h :
-
Coefficient of permeability in radial direction (m/s)
- \(\bar{k}_{h}\) :
-
Average coefficient of permeability in radial direction (m/s)
- k s :
-
Coefficient of permeability in smear zone (m/s)
- k w :
-
Coefficient of permeability of drain (m/s)
- k wo :
-
Initial value of kw (m/s)
- m v :
-
Coefficient of volume compressibility (MPa−1)
- n :
-
Drain spacing ratio, (\(n = \frac{{r_{e} }}{{r_{w} }}\))
- q r :
-
Water flow in unit cell
- q w :
-
Discharge capacity of drain (m3/year)
- q wo :
-
Initial value of qw (m3/year)
- q wz :
-
Value of qw at depth z (m3/year)
- r :
-
Radius (m)
- r e :
-
Radius of the unit cell
- r s :
-
Radius of the smear zone
- r w :
-
Radius of the drain
- s :
-
Smear ratio (\(s = \frac{{d_{s} }}{{d_{w} }}\))
- T h :
-
Time factor in horizontal direction (dimensionless)
- u :
-
Excess pore water pressure (kPa)
- \(\bar{u}_{r}\) :
-
Average excess pore water pressure in unit cell (kPa)
- \(u_{o}\) :
-
Initial excess pore water pressure (kPa)
- \(\bar{u}_{w}\) :
-
Average excess pore water pressure at drain (kPa)
- U r :
-
Degree of radial consolidation (%)
- z :
-
Depth (m)
- V :
-
Volume of the soil mass (m3)
- \(\varepsilon_{v}\) :
-
Vertical strain at any depth
- \(\gamma_{sat}\) :
-
Unit weight of saturated soil (kPa/m3)
- \(\gamma_{w}\) :
-
Unit weight of water (kPa/m3)
- \(\sigma\) :
-
Total stress (kPa)
- \(\mu\) :
-
Factor used considering effects of smear zone and well resistance
- \(\bar{\mu }\) :
-
Average value of \(\mu\) with depth
- \(\bar{\mu }_{H}\) :
-
Value of \(\bar{\mu }\) in Hansbo’s solution
- \(\bar{\mu }_{D}\) :
-
Value of \(\bar{\mu }\) in Deng et al. (2013) solution
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The support of this research by the Industrial University of Ho Chi Minh City is gratefully acknowledged.
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Nguyen, BP. Nonlinear Analytical Modeling of Vertical Drain-Installed Soft Soil Considering a Varied Discharge Capacity. Geotech Geol Eng 39, 119–134 (2021). https://doi.org/10.1007/s10706-020-01477-1
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DOI: https://doi.org/10.1007/s10706-020-01477-1