Influence of Internal Erosion on Rainfall-Induced Instability of Layered Deposited-Soil Slopes
Abstract
:1. Introduction
2. Physical Processes and Mathematical Modeling Framework
2.1. Overview of the Main Physical Processes
2.2. Mathematical Framework
3. 1D Simulation of Seepage–Erosion Process in Layered Soil Column
4. 2D Simulation of Rainfall-Induced Seepage–Erosion Process within Layered Slopes
5. Conclusions
- (a)
- The seepage-induced internal-erosion process within layered deposited slopes will impose a significant influence on their failure patterns and mechanisms under rainfall. Except for the surface coarsening effect with accelerated infiltration reported previously (e.g., in Cui et al. (2014) [7] and Lei (2022) [30]) for single-layer deposited slopes, the fines migration around the soil layer interface can lead to the generation of a continuous subsurface stormflow above the layer interface, which would increase the pore-water pressure and weaken the soil strength and, hence, decrease the slope stability along the layer interface continuously;
- (b)
- The layered deposited-soil slope prone to internal erosion may fail gradually after sufficiently long rainfall infiltration due to the accumulated weakening of the soils. Further, the fines deposition process may turn a relatively highly permeable lower layer into a less permeable soil layer, which could also lead to the gradual failure within the layered slope with an initial highly permeable lower layer;
- (c)
- Due to the concealed and impactful nature of seepage-induced internal erosion, special attention should be paid when analyzing the stability of these layered deposited-soil slopes. The coupled seepage–erosion FEM presented in this paper could serve as a useful mathematical tool to analyze the intrinsic failure mechanism and stability evolution of such slopes under rainfall infiltration.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
Appendix A
Case | Number of Meshes in Upper Layer | Number of Meshes in Lower Layer |
---|---|---|
Varied | 8 | 10 |
Lv = 0.125 | 8 | 16 |
Lv = 0.167 | 6 | 12 |
Lv = 0.200 | 5 | 10 |
Lvup = 0.200 Lvlow = 0.250 | 5 | 8 |
Lvup = 0.250 Lvlow = 0.200 | 4 | 10 |
Lv = 0.250 | 4 | 8 |
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Parameter | Upper Layer | Lower Layer | Parameter | Upper Layer | Lower Layer |
---|---|---|---|---|---|
Initial saturated conductivity (m/s) | 3.21 × 10−6 | 8.42 × 10−7 | Initial fine fraction | 0.61 | 0.71 |
Initial porosity | 0.5 | 0.5 | Erosion coefficient | 0.7 | 0.0 |
Maximum saturation | 1 | 1 | Soil erosion sensitivity | 1.5 | - |
Residual saturation | 0.157 | 0.28 | Reference velocity (m/s) | 6 × 10−8 | - |
SWCC fitting parameter () | 0.105 | 0.086 | Reference ultimate fine fraction | 0.58 | - |
SWCC fitting parameter | 1.547 | 1.611 | Deposition coefficient | 0.0 | 0.4 |
Soil intrinsic density () | 1370 | 1500 | Permeability damage parameter | 0.05 | 0.05 |
Initial erodible-fines mass fraction () | 831 | 1072 | Permeability damage parameter | 3 | 3 |
Parameter | Upper Layer | Lower Layer | Parameter | Upper Layer | Lower Layer |
---|---|---|---|---|---|
Initial saturated conductivity (m/s) | 3.66 × 10−5 | 1.42 × 10−6 | Erosion coefficient | 0.022 | 0 |
Initial porosity | 0.35 | 0.35 | Soil erosion sensitivity | 4.76 | - |
Maximum saturation | 1 | 1 | Reference velocity (m/s) | 3.6 × 10−7 | - |
Residual saturation | 0.17 | 0.16 | Reference ultimate fine fraction | 0.193 | - |
SWCC fitting parameter () | 0.04 | 0.105 | Deposition coefficient | 0 | 0.4 |
SWCC fitting parameter | 1.27 | 1.547 | Permeability damage parameter | 0.05 | 0.05 |
Soil intrinsic density () | 2240 | 2240 | Permeability damage parameter | 3 | 3 |
Initial erodible-fines mass fraction () | 448 | 448 | Initial cohesion () | 2.5 | 2.5 |
Initial fine fraction | 0.2 | 0.2 | Initial internal-friction angle () | 25 | 25 |
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Lei, X.; Zhang, W.; Chen, X.; Ming, L. Influence of Internal Erosion on Rainfall-Induced Instability of Layered Deposited-Soil Slopes. Mathematics 2023, 11, 4348. https://doi.org/10.3390/math11204348
Lei X, Zhang W, Chen X, Ming L. Influence of Internal Erosion on Rainfall-Induced Instability of Layered Deposited-Soil Slopes. Mathematics. 2023; 11(20):4348. https://doi.org/10.3390/math11204348
Chicago/Turabian StyleLei, Xiaoqin, Weiyu Zhang, Xiaoqing Chen, and Liu Ming. 2023. "Influence of Internal Erosion on Rainfall-Induced Instability of Layered Deposited-Soil Slopes" Mathematics 11, no. 20: 4348. https://doi.org/10.3390/math11204348
APA StyleLei, X., Zhang, W., Chen, X., & Ming, L. (2023). Influence of Internal Erosion on Rainfall-Induced Instability of Layered Deposited-Soil Slopes. Mathematics, 11(20), 4348. https://doi.org/10.3390/math11204348