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Pseudo-Dynamic Approach to Analyze the Seismic Stability of Reinforced Soil Wall for cϕ Soil Backfill

  • Ashish Gupta
  • V. A. SawantEmail author
Original Paper
  • 17 Downloads

Abstract

In the design of reinforced soil wall, soil is considered as cohesionless. In earthquake-prone regions, analysis is based on either pseudo-static or pseudo-dynamic approach. Very few studies have considered behavior of reinforced soil walls assuming cϕ soil backfill in the pseudo-dynamic approach. Present study is aimed to investigate the seismic stability of reinforced soil wall incorporating the pseudo-dynamic approach. The propagation of primary and shear waves is considered under both horizontal and vertical seismic accelerations incorporating effect of soil amplification. A numerical algorithm is proposed to obtain the required strength of reinforcements, critical angle of failure wedge, and factor of safety of the reinforced soil wall for specific number of reinforcement layers and length of reinforcement. The effects of shear strength parameters, coefficients of ground accelerations, and soil amplification factor on the stability of the reinforced soil wall are critically examined. Variation in the mobilized pullout resistance of reinforcement layers and associated factor of safety with time is considered in the assessment of stability. For cϕ soil backfill, numerical predictions are in good agreement when compared with available studies in the literature for validation purpose.

Keywords

Factor of safety Pseudo-dynamic approach Reinforced soil wall Seismic stability 

List of Symbols

TTot

Total required strength of n number of reinforcement (kN/m)

tTot

Total pullout force in the n number of reinforcement (kN/m)

γ

Unit weight of soil (kN/m3)

ω

Angular frequency (rad/s)

α

Assumed failure plane making an angle with the horizontal (°)

ψ

Time for propagating primary wave (s)

ζ

Time for propagating shear wave (s)

η

Wavelength of the vertically propagating primary wave (m)

αcri

Critical angle of the failure wedge (°)

af

Adhesion factor

ah

Horizontal seismic acceleration (m/s2)

av

Vertical seismic acceleration (m/s2)

c

Soil cohesion (kPa)

C

Total cohesive force (kN/m)

c*

Normalized cohesion of soil (dimensionless)

ca

Soil-wall adhesion (kPa)

Ca

Total adhesive force (kN/m)

F

Resultant of shear and normal forces (kN/m)

fa

Soil amplification factor at top level

fz

Soil amplification factor at depth z

g

Acceleration due to gravity force

H

Height of wall (m)

Hi

Depth of embedment

K

Normalized required strength of reinforcement

kh

Horizontal seismic coefficient

Kmax

Required maximum strength of reinforcement (dimensionless)

kv

Vertical seismic coefficient

Li

Effective length of ith layer of reinforcement

Lr

Length of reinforcement layer

n

Total number of reinforcement layer

Qht

Total inertia force in horizontal direction (kN/m)

Qvt

Total inertia force in vertical direction (kN/m)

Sv

Reinforcement layer spacing

T

Period of lateral shaking (s)

ti

Tensile force mobilized in the ith layer of reinforcement (kN/m)

Ti

Tension force generated in the ith layer of reinforcement (kN/m)

Vp

Primary wave velocity (m/s)

Vs

Shear wave velocity (m/s)

W

Weight of soil backfill (kN/m)

λ

Wavelength of the vertically propagating shear wave (m)

ϕ

Soil friction angle (°)

ϕr

Interface friction angle between the soil and reinforcement

Notes

References

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Copyright information

© Indian Geotechnical Society 2019

Authors and Affiliations

  1. 1.Department of Civil EngineeringIndian Institute of Technology RoorkeeRoorkeeIndia

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