Influence of Friction Angles on Earth Pressures in Dry Granular Flow Dynamics and Soil Mechanics

Abstract

The earth pressure coefficient (K) determines the nature of (tendency of) deformation of the granular mass during flow or deposition. When flow velocity is increasing, K takes its active state Kact and the flow is divergent. When the flow velocity is decreasing, K takes its passive state Kpas and the flow is convergent. The mathematical relations presented here and their 2-D and 3-D plots highlight that the passive and active earth coefficients strongly depend on the internal angle (δ) and basal angle (ϕ) of frictions. The mathematical relation for dry granular mass flow is extended to find these coefficients in soil mechanics. Results further show that active earth pressure drops as the internal angle of friction increases, but passive earth pressure rises. The earth's pressure is at rest if the wall is in its natural position

Characterizing the Effects of Friction Angles on Earth Pressures in the Flow of Granular Mass along Down-slope and Cross-slope in a Rough Incline

“…It is reasonable to suppose that the lateral confinement pressure 𝜎 𝑦𝑦 is close to the principal stress say 𝜎 1 because the majority of shearing occurs on vertical surfaces that are parallel to the direction of tangential velocity. The major principal stress is given by (Savage & Hutter, 1989;Kafle et al, 2023b)…”

“…Earth pressure problems encountered in engineering practice are concerned with the determination of internal stresses acting on the soil masses or the stresses between the soils and the contiguous structures (Abdul, 1966;Lin et al, 2020). Earth pressure is the lateral force exerted by the backfill on the retaining structures (Kafle et al, 2016;Kafle et al, 2019;Kafle et al, 2023b). The retaining wall frequently pulls away from the backfill as a result of excessive pressure from the retained soil.…”

“…The retaining wall frequently pulls away from the backfill as a result of excessive pressure from the retained soil. By resisting forces that are created along the plane of the failure wedge in a direction away from the retaining wall due to the soil's shear strength, the retaining wall is kept in equilibrium (Pirulli et al, 2007;Khosravi et al, 2016;Kafle et al, 2023b). The pressure is limited by the distance that the retaining wall may move from the backfill.…”

“…Active earth pressure is the least amount of pressure the soil can apply to the retaining wall (Levesque et al, 2017). The earth pressure increases whenever the retaining wall shifts toward the backfill as a result of any natural event because the retaining soil becomes compressed, increasing its shearing strength (Kafle et al, 2023b). When the soil's shearing resistance has fully mobilized, the pressure has reached its maximum level.…”

“…Its value exceeds limiting active pressure but falls short of passive pressure (Abdul, 1966;Pudasaini & Hutter, 2007;Lin et al, 2020). The largely unpredictable and devastating natural events like landslides, rockfalls, and snow and ice avalanches occur on steep slopes of mountainous regions that can travel large distances before they come to rest and they frequently pose a threat to human life and their settlements (Kafle et al, 2016;Kafle et al, 2019;Kafle et al, 2022;Kafle et al, 2023a;Kafle et al, 2023b). It is extremely challenging and complex to direct observation of the movement of rockfalls or avalanches which is possible only by remote sensing techniques (Gubler, 1987).…”