Lateral earth pressures in constrained landslides

Abstract

The problem of the limiting landslide pressure on an obstacle was first formulated in 1944 by Robert Haefeli of ETH Zurich, who recognised that the kinematics of the problem does not allow for classical active and passive earth pressure theories to be applied. He derived an approximate solution using a limit equilibrium approach with a number of rather arbitrary assumptions and simplifications. Since then, the Haefeli solution has been widely applied for the design and analysis of landslide retaining structures. The paper revisits this old landslide pressure problem by means of a rigorous upper- and lower-bound limit analysis and derives the exact landslide pressure solution for a planar landslide with a weak slip surface parallel to the slope. Being applicable to a wide range of natural and man-made obstacles and, unlike the classical theories, not affected by the wall friction and soil dilation, the upper-bound solution is rather robust. The landslide pressures from this solution increase with the strength of the sliding layer and are significantly higher than the active, but much lower than the passive, earth pressures. Of even higher practical importance, however, is that due to their oversimplifying assumptions, the widely used approximate solutions appear to get close to the exact solution only over a very narrow range of slope and friction angles. It appears that for mildly inclined weak slip surfaces and high strengths of the sliding layer, analysis and design of retaining structures based on well-known approximate solutions can become dramatically unsafe.

A limit equilibrium method for the limiting landslide pressure acting on a retaining structure

“…The Rankine method can be used in the case of 0  = , and the results correspond to the conclusions of Muraro et al (2015) and Friedli et al (2017). A comparison between the LEM and the FEM shows that the LEM results in a smaller numerical error that can be ignored in practical applications.…”

“…Problem Formulation Friedli et al (2017) proposed a landslide model based on limit analysis for determining the limiting landslide forces on a constrained retaining structure. As shown in Fig.…”

“…For this special case, classical earth pressure theories, such as Coulomb's (1776) theory, Rankine's (1857) theory, and logarithmic spiral theory (Terzaghi et al, 1996), are not suitable for calculating the limiting landslide force. Friedli et al (2017) andFriedli et al (2021) proposed a limit analysis method to determine the lateral earth pressure of a constrained landslide, which is significantly higher than the active earth pressure but much lower than the passive earth pressure. One of the assumptions in the limit analysis was that the friction angle of the weak layer is equal to the slope angle of the weak layer.…”

“…Both of these studies involved infinite landslides, and the upper and lower boundaries of the sliding layers were parallel. Moreover, Friedli et al (2017) pointed out that the earth pressure in constrained planar landslides, which is different from the active and passive earth pressures, is a special case because the retaining structure is hardly moving during the landslide's movement. For this special case, classical earth pressure theories, such as Coulomb's (1776) theory, Rankine's (1857) theory, and logarithmic spiral theory (Terzaghi et al, 1996), are not suitable for calculating the limiting landslide force.…”

A calculation method for the embedded depth of stabilizing piles in reinforced slopes

“…For a slope reinforced with embedded piles, overtop‐sliding failure is a potential occurrence . To maximize the anti‐sliding effect of the embedded stabilizing piles, the determination of the embedded depth of the pile top is significant in practice.…”