Dynamic behavior of reinforced slopes: horizontal acceleration response

Abstract

Shaking-table tests on plane-strain geosynthetic-reinforced model slopes using stepwise intensified sinusoidal pulse loads with specific frequencies were conducted to investigate the influence of peak ground accelerations, wave frequencies and plastic slope displacements on the horizontal acceleration response of the slope. A comparative study on the crest response behavior suggested that the tests using pulse loads give useful insights into the dynamic behavior of soil structures subjected to earthquake loads. Test results indicate that both the horizontal acceleration response at the crest and the lateral slope displacement are influenced by the horizontal peak ground acceleration, the wave frequency, and the cumulative permanent displacement of the slope. Amplification factors at the crest of the slope are functions of input wave frequencies; they decrease exponentially with increasing input horizontal peak ground acceleration. Transitions from an amplification state to a de-amplification state at the slope crest occur at certain levels of input ground accelerations, which are associated with the development of major slip planes in the slope mass (or with noticeable slope displacement). It was found that a ratio between the plastic slope displacement and the total slope height (Dmax/Ht) of the order of 0.42–5.9 × 10−2 is relevant to this amplification–deamplification transition. A practical implication of these observations is that the resonance acceleration of the slope is a major factor that needs to be considered in seismic stability analyses of reinforced slopes with a small plastic slope displacement of Dmax/Ht ≈ 2.5 × 10−3; it does not need to be considered in the seismic stability evaluation for reinforced slopes with plastic slope displacements of Dmax/Ht = 5.0–5.9 × 10−2.

Settlement of footings at the crest of reinforced slopes subjected to toe unloading

“…Physical and mechanical properties of the reinforcement are summarized in Table 1. Previous studies that used this reinforcing material for a model slope with a similar height (Huang et al 2010(Huang et al , 2011 found that tensile strains of the reinforcement under working load conditions are about 1.2-3.2%, which is consistent with the in situ working strain condition for typical stiff geosynthetic reinforcement materials. The geosynthetic reinforcement has a wide-width ultimate tensile stress of T f = 4.0 kN/m and a tensile strain at breakage of ε f = 37%, as summarized in Table 1 and Figure 2.…”

“…a similar stress level in a 2 m high (= 0.5 m × 4) slope. Therefore, the present study investigates the behaviour of a 2 m high slope consisting of uniform, round, gravel particles with a size of 7.84 mm (= 1.96 mm × 4) according to the similitude of particle size (Huang et al 2010(Huang et al , 2011. Before the construction of model slopes, a rigid vertical steel wall was placed at a specific location according to the required value of H (the height of toe unloading).…”

Seismic Response of Soil Slopes in Shaking Table Tests: Effect of Type and Quantity of Reinforcement

“…Many shaking table model studies on slopes in literature have used much smaller slope models in experiments. For example, Lo Grasso et al [12] and Lin and Wang [8] used slopes of 0.5 m height and Huang et al [9] used model slopes of 0.48 m height. Though scale effects cannot be completely eliminated in 1-g model studies, similitude laws to correlate the model and prototype scaling and response are effectively used by several researchers.…”

“…It was observed that the response of the soil converted from linear to nonlinear at the acceleration amplitude of 0.5 g. The failure surface appeared to be fairly shallow and confined to the slope surface, which was consistent with the field observations of earthquake-induced landslides. Huang et al [9] performed a series of full-scale shaking table tests on reinforced soil slopes subjected to stepwise intensified sinusoidal pulse loads with various frequencies and reported that accelerations and displacements of the slopes showed frequency dependent behaviour. Transition from the state of amplification towards the state of deamplification at the crest of the slope consistently preceded the critical collapse state of the slopes.…”

Acceleration-Amplified Responses of Geosynthetic-Reinforced Soil Structures with a Wide Range of Input Ground Accelerations

“…In this approach, horizontal acceleration, a h , within GRS structures is an important parameter when evaluating seismic earth pressure. As seismic waves pass from the ground into GRS structures, amplification or attenuation of horizontal acceleration, a h , relative to input ground acceleration, a g , has been reported by several studies using numerical simulations (Bathurst and Hatami 1998), shaking-table tests (Huang et al 2010;Krishna and Latha 2007;Matsuo et al 1998) and dynamic centrifuge tests (Hung et al 2011;Liu et al 2010).…”