Lateral Earth Pressure Distribution Research Articles

Engineering behaviors of reinforced gabion retaining wall based on laboratory test

In order to study the engineering behaviors of reinforced gabion retaining wall, laboratory model test was carried out. Cyclic load and unload of five levels (0–50, 0–100, 0–50, 0–200 and 0–250 kPa) were imposed. Vertical earth pressure, lateral earth pressure, deformation behaviors of reinforcements, potential failure surface and deformation behaviors of wall face were studied. Results show that vertical earth pressure is less than theoretical value, the ratio of vertical earth pressure to theoretical value increases nearly linearly with increasing load, and the correlation coefficient of regression equation is 0.92 for the second layer and 0.79 for the fifth layer. The distribution of lateral earth pressure along the wall back is nonlinear and it is less than theoretical value especially when the load imposed at the top of retaining wall is large. Therefore, reinforced gabion retaining wall will be in great safety when current method is adopted. The deformation behaviors of reinforcements both in the third layer and the fifth layer are single-peak distributions, and the position of the maximum strain is behind that determined by 0.3H (Here H refers to the height of retaining wall) method or Rankine theory. Lateral deformation of wall face increases with increasing load, and the largest lateral deformation occurs in the fourth layer, which lead to a bulging in the middle of wall face.

Estimation of the Passive Earth Pressure with Inclined Cohesive Backfills: The Effect of Intermediate Principal Stress is Considered

Estimating passive earth pressure accurately is very important when designing retaining wall. Based on the unified strength theory and plane strain assumption, an analytical solution has been developed to determine the passive lateral earth pressure distribution on a retaining structure when the backfill is cohesive and inclined considering the effect of the intermediate principal stress. The solution derived encompasses both Bell’s equation (for cohesive or cohesionless backfill with a horizontal ground surface) and Rankine’s solution (for cohesionless backfill with an inclined ground surface).

Pseudo-static lateral earth pressures on broken-back retaining walls

Displacement of retaining walls during earthquakes causes damage to the structures founded on their backfill. The displacement of the wall can be reduced by decreasing the lateral earth pressure applied on its back. This can be achieved in a broken-back wall as the size of the failure wedge formed behind the wall is reduced; therefore, the calculation of lateral earth pressures is essential in assessing the safety of and designing broken-back retaining walls. In this study, a series of reduced-scale shaking table model experiments were performed on broken-back quay walls composed of concrete blocks with two different rear-face shapes. In comparison with a vertical-back wall, earth pressures increased at the upper forward (i.e., seaward) leaning rear-face segments of the wall, whereas they decreased at lower backward (i.e., landward) leaning elevations. Because of the wide application of the pseudo-static method of Mononobe–Okabe in engineering practice and design codes, lateral earth pressures have also been estimated using this approach. The comparison between the measured lateral earth pressures and those calculated using the Mononobe–Okabe method shows fairly good agreement in predicting the overall distribution of lateral active earth pressure during and after the shaking.

A numerical study on the use of geofoam to increase the external stability of reinforced soil walls

The potential benefit of placing a panel of compressible (i.e. expanded polystyrene) geofoam behind the reinforced zone of mechanically stabilized earth (MSE) walls is investigated using a numerical modeling approach. A panel of geofoam is placed immediately behind the reinforced zone during the construction phase of an idealized plane-strain reinforced soil segmental wall model. The analysis procedure includes the modeling of soil compaction. The magnitudes and distributions of earth pressure behind the reinforced zone in the wall models with and without the geofoam panel are compared to quantify the reductions in lateral earth pressure, resultant lateral force and overturning moment expected due to the placement of the geofoam material. Predicted magnitudes of facing lateral deformation and reinforcement strains are also compared among cases studied in order to evaluate the effect of geofoam on wall serviceability. It is shown that placing geofoam behind the reinforced zone can reduce the maximum lateral earth pressure behind this zone by as much as 50% depending on the geofoam thickness and stiffness values. The magnitudes of total lateral earth force (i.e. the resultant force of the lateral earth pressure distribution) behind the reinforced mass and overturning moment about the wall toe are shown to decrease by 31% and 26%, respectively. These findings point to a significant potential for using geofoam to reduce the lateral earth pressure demand on MSE walls (i.e. as opposed to rigid retaining walls examined previously) and thereby increase their serviceability and their factors of safety against external instability.

Modifying the mechanism method of masonry arch bridge analysis

A typical stone masonry arch bridge (Bargower bridge) was assessed by the mechanism method. The collapse load prediction from this method depended on the assumed distribution of lateral earth pressures on the extrados. The arch profile at the onset of failure deviated significantly from its original form. Mechanism analysis is accurate only when all the forces and their positions are known. The authors modified the mechanism method by including a deflection-dependent pressure updating algorithm. Results confirmed that arch deflections had a significant influence on the prediction of the assessed collapse load compared to that observed at Bargower. The problem of predicting exactly what deflection pertains to the collapse state remains a matter for future research.

Seismic Behavior of Cantilever Retaining Walls with Liquefiable Backfills

A series of centrifuge tests were conducted to investigate the seismic behavior of fixed-base, cantilever, retaining walls supporting saturated, liquefiable, cohesionless backfills. Accelerations, bending strains, deflections, and lateral earth pressures were measured on the walls. Accelerations, pore pressures, and surface settlements were measured in the soil. Parametric studies investigating effects of wall stiffness and magnitude of shaking on the wall-soil behavior were conducted. The magnitude and distribution of lateral earth pressures were determined. Experimental results demonstrated that excess pore pressures in liquefiable backfills contribute significantly to seismic, lateral, earth pressures. It was shown that the average rise in the dynamic thrust is well correlated to the excess pore pressures in the backfill but is insensitive to the range of wall stiffness. It was found that simple calculations, based on Coulomb's active earth pressure theory, can be used to estimate the dynamic thrust at...

Active earth pressure in cohesive soils with an inclined ground surface

An analytical solution is developed to determine the active lateral earth pressure distribution on a retaining structure when it consists of a cohesive backfill (internal friction angle ϕ > 0, cohesion c > 0) with an inclined ground surface. The solution derived encompasses both Bell's equation (for cohesive or cohesionless backfill with a horizontal ground surface) and Rankine's solution (for cohesionless backfill with an inclined ground surface). The orientation of the failure surface is also determined. Results indicate that, unlike the soil-wall scenarios of Bell and Rankine where the failure planes are parallel with a fixed orientation independent of the overburden pressure, for sloping cohesive backfill (ϕ > 0, c > 0) the slope of the failure surface is a function of the overburden pressure and becomes shallower with depth, thus forming a curvilinear failure surface. The solution developed can also be used to check the sustainability of a slope. The analytical solution can be programmed conveniently in a computer.Key words: retaining structure, active earth pressure, cohesive backfill.

Lateral Earth Pressure Analysis using Relevant Soil Modulus

ABSTRACT The effect of soil modulus, mode of wall movement and base friction conditions, on lateral earth pressure distribution and pattern of failure development in the soil mass is brought out.