Fig 1.
Test system diagram.
Fig 2.
Model test site photos.
Fig 3.
Arrangement of sensors.
Fig 4.
Particle grading curve of soil samples.
Table 1.
Characteristics of soil samples for indoor test.
Table 2.
Indoor test parameters and protocols.
Fig 5.
Slope ultimate failure shape for each test.
(a) T1-1, (b) T2-1, (c) T3-1, (d) T1-2, (e) T2-2, (f) T3-2.
Fig 6.
(a) 1254s Initial state, (b) 1794s Cracks appear at the toe of the slope, (c) 2034s Crack propagation, (d) 2334s Cracks run through to the top of the slope, (e) 4434s Gradual retreat failure of soil between slope toe, (f) 5694s Collapse at the toe of the slope, forming another continuous gully, (g) 7614s Collapse of soil between gullies, (h) 12354s Gully edge extension.
Fig 7.
Schematic diagram of the development process of pure loess spoil slope failure induced by rainfall.
Fig 8.
(a) 1740s Initial state, (b) 2340s Cracks appear at the toe of the slope, (c) 2520s Cracks run through to the top of the slope, (d) 4200s Gully is forming, (e) 4560s Gully Continuous widening, (f) 6360s Gully Continuous widening, (g) 7260s Forming a regional landslide, (h) 18060s Small particles of loess are carried away by water.
Fig 9.
The process schematic diagram of test T1-2.
Fig 10.
The process diagrams of test T2-2.
(a) At 10th sec. Initial state after excavation, slight tension cracks appear, (b) At 70th sec. Local collapse and crack expansion, (c)At 190th sec. The second step collapses and new tension cracks appear, (d) At 370th sec. The collapse range extends backward, (e) At 490th sec. The collapse extends to the top of the slope, (f) At 790th sec. Collapse range lateral expansion, (g) At 1330th sec. Some parts form a gentle slope, (h) At 2110th sec. The original gully area expansion.
Fig 11.
The process diagrams of test T3-2.
(a) At 1860th sec. Initial state after excavation slope toe, (b) At 3780th sec. Slight local collapse at the toe of the slope, (c) At 8940th sec. Forming linking cracks, (d) At 12000th sec. Forming a shallow landslide of fan-shaped.
Fig 12.
The relationship between displacement, rainfall intensity, and time.
(a) S1, (b) S2, (c) S3.
Fig 13.
The relationship between pore pressure and rainfall intensity.
(a) S1, (b) S2, (c) S3.
Fig 14.
The relationship between pore pressure and rainfall intensity after excavation of slope toe.
(a) Test T1-2, S1, (b) Test T3-2, S3.