Evaluation of failure of slopes with shaking-induced cracks in response to rainfall

Abstract

Centrifuge model tests on slopes subject to shaking and rainfall have been performed to examine the response of slopes with shaking-induced cracks to subsequent rainfall and evaluate the corresponding landslide-triggering mechanisms. The failure pattern of the slope subject to shaking and then rainfall was found different from that of the slope subject to only rainfall. When shaking caused cracks on the slope shoulder and rupture line below, the mobilized soil slid along the slip surface that extended to the rupture line, the main crack became the crown of the undisturbed ground once the slope was subject to a subsequent rain event, and the progression of the landslide was related to the rainfall intensity. During the landslide caused by light rainfall, the main scarp kept exposing itself in the vertically downward direction while the ground behind the main crack in the crack-containing slope remained undisturbed. The detrimental effect of cracks on soil displacement was more evident when the slope was exposed to heavy post-shaking rainfall, resulting in a rapid and massive landslide. Additionally, the volume of displaced material of the landslide, the main scarp area on the upper edge, and the zone of accumulation were larger in the crack-containing slope subject to heavy rainfall, in comparison with those in the crack-free slope. The deformation pattern of slopes with shaking-induced cracks during rainfall was closely related to rainfall intensity and the factor of safety provided a preliminary estimation of slope stability during rainfall. Moreover, even when subjected to the same rainfall, the slopes with antecedent shaking-induced cracks displayed different levels of deformation. The slope that experienced larger shaking had greater deformation under the following rainfall, and the shaking-induced slope deformation also controlled the slip surface location. Finally, the velocity of rainfall-induced landslide could be greatly influenced by the prior shaking event alone. Despite being under light rainfall, the slope that has encountered intense previous shaking exhibited an instant landslide.

Limit Equilibrium Analysis of Landfill Instability Based on Actual Failure Surface

“…substituting Equations ( 29)- (31) into Equation (28) gives Limit equilibrium analysis of the passive wedge is carried out, and the balance of vertical and horizontal forces is taken into account, which can be expressed as:…”

“…The geometric parameters of the model are shown in Figure 5a, taking centrifugal test 3 in [28] as an example: γ = 7 kN/m 3 , γ sat = 12 kN/m 3 . It can be obtained that the water level h/overall slope height H (water level ratio) h/H = 0.79 when the overall slip occurs, and the shear strength corresponding to 20% failure strain is taken: δ A = ϕ sw = 28.6 • , δ P = 12.8 • , c A = c sw = 24 kPa, C P = 0, and β = 55.3 The geometric parameters of the model are shown in Figure 5a, taking centrifugal test 3 in [28] as an example: γ = 7 kN/m 3 , γsat = 12 kN/m 3 . It can be obtained that the water level h/overall slope height H (water level ratio) h/H = 0.79 when the overall slip occurs, and the shear strength corresponding to 20% failure strain is taken: δA = φsw = 28.6°, δP = 12.8°, cA = csw = 24 kPa, CP = 0, and β = 55.3°.…”

“…The parameters in the experiment are as follows: γ = 9 kN/m 3 ; γ sat = 12.6 kN/m 3 ; and, when damage occurs, the water level ratio is h/H = 0.85. Similarly, select the shear strength corresponding to 20% failure strain: The geometric parameters of the model are shown in Figure 5a, taking centrifugal test 3 in [28] as an example: γ = 7 kN/m 3 , γsat = 12 kN/m 3 . It can be obtained that the water level h/overall slope height H (water level ratio) h/H = 0.79 when the overall slip occurs, and the shear strength corresponding to 20% failure strain is taken: δA = φsw = 28.6°, δP = 12.8°, cA = csw = 24 kPa, CP = 0, and β = 55.3°.…”

“…However, it is difficult to model such a large geological landfill, and the influencing factors are complex; so, the centrifugal model test becomes a possible method to study landslide instability [26,27]. The centrifuge applies N times the gravity acceleration to the scaled model, achieving the same self-weight stress in the model as the prototype, with the prototype's scale model macroscopic geometry size reduced by N times [28]. Therefore, the application of the centrifugal model to the study of slope stability in landfills has many advantages, such as the same stress conditions as large-scale geological slopes, easy-to-realize variation in water level, and simple model preparation.…”

Evaluation of safety state for dump slope in-service under severe drying-wetting cycles at high altitude

“…Generally, the continual drop of the shear strength of soil significantly contributes to the failure of slopes during rainfall 3,4 . For example, Li et al 5 discussed the mechanisms through which excavation and rainfall affect slope stability and established a numerical model to simulate rainfall infiltration.…”