Abstract
The frame beam anchor plate (FBAP) reinforced slope has been popularized and applied in some fill slope projects. Nevertheless, the existing design method ignores the influence of earthquake action and the suction effect of unsaturated soils. The stability of unsaturated soil slopes reinforced with FBAPs under an earthquake is analyzed based on the upper bound theorem of limit analysis and pseudo-dynamic method to solve the above problems. The influence of the suction effect on the effective weight and strength of unsaturated soils under one-dimensional steady seepage conditions was considered in the derivation of the energy balance equation. A simplified method based on the volume integral of the rotating body is used to calculate the external work rate. Two possible failure modes of anchorage structures are considered when solving internal energy dissipation. Results show that the influence of suction and seepage conditions on slope stability decreases with the increasing soil pore size distribution parameter n and saturated hydraulic conductivity ks. Also, the stability of the slopes is significantly improved with the increase of total rows of anchor plates. Likewise, the stability of slopes decreases with the increase in the horizontal seismic coefficient kh and amplification coefficient fa.
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Abbreviations
- 1, 2, …, i, …, m :
-
Serial numbers of anchor plates
- c :
-
Total cohesion
- c′ :
-
Effective cohesion
- c″ :
-
Capillary cohesion −σstanφ′
- D :
-
Internal energy dissipation
- D c′ :
-
Energy dissipation rate caused by effective cohesion
- D c″ :
-
Energy dissipation rate caused by capillary cohesion
- D T :
-
Energy dissipation rate caused by anchor plates
- f a :
-
Acceleration amplification factor
- F i :
-
Shear resistance
- F S :
-
Safety factor
- f y, A s :
-
Yield strength and cross-sectional area of tie rod
- G s :
-
Soil-specific gravity
- H :
-
Slope height
- h i :
-
Burial depth
- K 0 :
-
Coefficient of earth pressure at rest
- K a :
-
Coefficient of active earth pressure
- k h :
-
Horizontal seismic coefficien
- k h(z, t):
-
Pseudo-dynamic horizontal seismic coefficient
- k s :
-
Saturated hydraulic conductivity
- K p :
-
Coefficient of passive earth pressure
- L :
-
Length of line segment AB in Fig. 3
- L a, L b, L h :
-
Length, width and thickness of anchor plate
- n :
-
Soil pore size distribution parameter
- P i :
-
Resistance generated at the front end of the anchor plate
- Q :
-
Uniformly distributed load at the top of a slope
- q :
-
Steady flow rate
- r, r 0 :
-
Polar diameters corresponding to angles θ and θ0
- R int :
-
Strength reduction coefficient
- r Ti, θ Ti :
-
Polar diameter and rotation angle corresponding to anchor plate
- S :
-
Pore-water degree of saturation
- S e :
-
Effective degree of saturation
- S r :
-
Residual degree of saturation
- t :
-
Time
- T 0 :
-
Seismic period
- T i :
-
Anchoring force
- T pi :
-
Ultimate pullout resistance of anchor plate
- T s :
-
Ultimate pullout resistance of tie rod
- u a :
-
Pore-air pressure
- u a − u w :
-
Matrix suction
- u w :
-
Pore-water pressure
- W :
-
External work rate
- W s :
-
External work rate caused by seismic force
- W Q :
-
External work rate caused by slope top overload
- W γ′ :
-
External work rate caused by soil weight
- z :
-
Vertical distance from a point in the slope body to the toe
- z 0 :
-
Vertical distance from the toe to the water table
- α :
-
Inverse of the air entry pressure
- β :
-
Slope inclination angle
- θ :
-
Rotation angle of failure mechanism
- θ B :
-
Rotation angle corresponding to the point B
- θ 0, θ h :
-
Minimum and maximum rotation angle of failure mechanism
- γ′ :
-
Effective unit weight of unsaturated soils
- γ s :
-
Unit weight of saturated soil
- γ w :
-
Unit weight of water
- φ′ :
-
Effective internal friction angle
- ν s :
-
Shear wave velocity
- σ :
-
Total stress
- σ′ :
-
Effective stress
- σ s :
-
Suction stress
- ξ :
-
Lateral pressure coefficient
- τ f :
-
Shear strength of unsaturated soil
- τ fi :
-
Interface shear strength
- ω :
-
Angular velocity
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Acknowledgments
This work was supported by the National Natural Science Foundation of China (No. 51978321, 52168050, 51768040), and the Changjiang Scholars and innovation team support program of the Ministry of Education of China (IRT_17R51), and the Department of education of Gansu Province: “star of Innovation” program for excellent postgraduates (2022CXZX-448). The financial supports are greatly appreciated. The authors also want to thank the anonymous reviewers for their valuable and helpful comments.
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Huang, A., Zhu, Y., Ye, S. et al. Seismic Stability Limit Analysis of Unsaturated Soil Slopes Reinforced by Frame Beam Anchor Plates. KSCE J Civ Eng 27, 3778–3792 (2023). https://doi.org/10.1007/s12205-023-1928-5
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DOI: https://doi.org/10.1007/s12205-023-1928-5