1. Optimization of embedded retaining walls under the effects of groundwater seepage using a reliability-based and partial factor design approachRok Varga, Bojan Žlender, Primož Jelušič, 2024, original scientific article Abstract: In this paper, a comparative analysis of the effects of groundwater, seepage and hydraulic heave on the optimal design of embedded retaining walls is carried out. The optimization model for an optimal retaining wall (ORW) minimizes the total length of the retaining wall considering design constraints. The model is extended to include the probability of failure as an additional constraint. This overcomes the limitations of the partial safety factor approach, which does not fully account for uncertainties in the soil. In contrast, the reliability-based design (RBD) approach integrates these uncertainties and enables an assessment of the impact of seepage and hydraulic heave on the reliability of the structure. A real-coded genetic algorithm was used to determine optimal designs for both optimization methods. The results of the case study show that the addition of seepage (groundwater flow) to the hydrostatic conditions has a modest effect on the embedment depth. The design based on partial safety factors, which takes seepage into account, leads to a slight increase in the embedment depth of 0.94% compared to a retaining wall design that only takes the hydrostatic conditions of the groundwater into account. When designing on the basis of probability failure, the percentage increase in embedment depth due to seepage is between 2.19% and 6.41%, depending on the target probability of failure. Furthermore, the hydraulic heave failure mechanism did not increase the required embedment depth of the retaining wall, which means that the failure mechanism of rotation near the base was decisive for the design.
Keywords: embedded retaining wall, reliability-based design, partial safety factor design, optimization, genetic algorithm
Published in DKUM: 10.12.2024; Views: 0; Downloads: 12
 Full text (2,13 MB)
This document has many files! More... |
2. Sustainable retaining wall solution as a mitigation strategy on steep slopes in soft rock massPrimož Jelušič, Goran Vlastelica, Bojan Žlender, 2024, original scientific article Abstract: Steep slopes in soft rock are characterized by their susceptibility to instability (rockfall,
rockslide) due to weathering and erosion of the slope surface. This article deals with the problem of
adapting to the increasing height of the scree slope. The construction of a retaining wall in a scree
slope in front of a slope of soft rock with a steep face, where a very rapid weathering and erosion
process of weathered material takes place, and the simultaneous deposition of material in front of
the steep slope is a common solution. Changes in the geometry of the slope and the front scree are
taken into account, and at the same time, sufficient safety against rockfall must be ensured. The
analysis is shown on a specific example of a steep flysch slope near Split, Dalmatia. The retaining
wall solutions are compared in terms of function, cost and sustainability. The construction of a single
colossal, reinforced concrete retaining wall shows that this solution is not feasible due to the high
construction costs and CO2 emissions of the retaining wall. A model was therefore developed to
determine the height of the retaining walls for different construction time intervals and distances
from the original rock face. The critical failure modes were investigated for various retaining wall
solutions with regard to the highest degree of utilization of the resistance, which also allows the
cost-optimized solutions to be determined. By building two or more successive retaining walls at
suitable intervals and at an appropriate distance from the original rock face, construction costs and
CO2 emissions can be significantly reduced.
Keywords: retaining wall, erosion, rockfall, steep slope, flysch, sustainable design, cost optimization
Published in DKUM: 09.12.2024; Views: 0; Downloads: 10
Full text (6,06 MB)
This document has many files! More... |
3. Numerical study of the dynamic active lateral earth pressure coefficient of cohesive soilsMehrab Jesmani, Hossein Alirezanejad, Hamed Faghihi Kashani, Mehrad Kamalzare, 2017, original scientific article Abstract: Retaining walls are proposed in many projects, such as bridges, coastal structures, road constructions and wherever lateral support is required for the vertical surface of an excavation. The active lateral pressure coefficient of soil, Ka , is an important parameter for studying the static and dynamic behaviors of these retaining walls. Many studies have evaluated this coefficient in static situations, but in most previous dynamic studies, researchers have worked on the behavior of cohesionless backfill soil or made simplifying assumptions (e.g., pseudo-static status) for cohesive soils as backfill soil. In this study, the size of the active lateral earth pressure coefficient (Ka) was studied in a full dynamic situation (Kae). A retaining wall with cohesive backfill soil is evaluated using the finite-difference method (FDM) and the effects of important soil and loading properties are assessed. The model is based on Mohr-Coulomb failure criteria under seismic loading. The results show that the value of Kae at the top of the wall, where it is highly sensitive to any variation in the soil and loading properties, is greater than one due to the high pressure value induced by the horizontal dynamic acceleration and the presence of tension cracks.
Keywords: dynamic active lateral earth pressure coefficient (Kae), cohesive backfill soil, finite difference method (FDM), tension cracks, retaining wall, seismic loading
Published in DKUM: 18.06.2018; Views: 1549; Downloads: 118
Full text (3,26 MB)
This document has many files! More... |
4. Design optimization for symmetrical gravity retaining wallsErol Sadoğlu, 2014, original scientific article Abstract: The optimization for symmetrical gravity retaining walls of different heights is examined in this study. For this purpose, an optimization problem of continuous functions is developed. The continuous functions are the objective function defined as the cross-sectional area of the wall and the constraint functions derived from external stability and internal stability verifications. The verifications are listed as the overturning, the forward sliding, the bearing capacity, the shears in the stem and the bendings in the stem. The heights of the walls are selected as 2.0, 3.0, and 4.0 m in order to investigate the outline of the optimum cross-section and the effect of the wall height on the outline. Additionally, the physical and mechanical properties of the soil are kept constant in order to compare only the effect of the height on the geometry. The upper and lower bounds of the solution space are specified to be as wide as possible and the minimum dimensions suggested for the gravity retaining walls are not taken into account. A common feature of the optimum cross-sections of walls with different heights is to have a very wide lower part like a wall foundation and a slender stem. However, other than the forward sliding constraint, the bending constraints are active at the optimum values of the variables.
Keywords: gravity retaining wall, nonlinear optimization, continuous variables, interior point method
Published in DKUM: 14.06.2018; Views: 1575; Downloads: 202
Full text (168,77 KB)
This document has many files! More... |
5. Load transfer and stress in a piled gravity retaining wallQun Chen, Li Wan, Changrong He, Zihui Lai, 2010, original scientific article Abstract: The piled retaining wall is a new type of railway retaining structure in China. In the current design, the retaining wall, the beam and the piles are assumed to be independent components. Both the mutual action of the retaining wall, the piles and beam, and the influence of the soil or rock foundation on the structure are not fully considered, so that there are some limitations in the current design method. In this paper, using field observations and a three-dimensional finite-element analysis, the lateral earth pressure on the wall back, the stress distributions and the forces of the reinforcements in the beam and the pile were studied. The simulation results were in good agreement with the field observation data. These results revealed that the tensile stresses were very small and that these stresses were positive in most zones in the beam and the pile. It can also be observed that the tensile stresses or forces in the beam and pile obtained in this study were much smaller than those obtained using the current design method. This clarified the fact that the current design method used for the beam and the pile was very conservative and that it should be optimized to consider the effect of the foundation on the whole structure and the interactions among the different components.
Keywords: piled gravity retaining wall, field observation, finite-element analysis, stress, load transfer mechanism
Published in DKUM: 11.06.2018; Views: 1156; Downloads: 92
Full text (558,92 KB)
This document has many files! More... |
6. Interactional approach of cantilever pile walls analysisStanislav Škrabl, 2006, original scientific article Abstract: This paper proposes a new method for the geomechanical analysis and design of cantilever retaining structures. It is based on the limit equilibrium method, but it uses some additional conditions for interaction between the retaining structure and the ground, when referring to the distribution of the mobilized earth pressures on the structure. The greatest benefit of the proposed method is shown in the analysis of structures of layered ground (heterogeneous above the dredge level and homogeneous below it), embedded in frictional and cohesive materials, and in the possibility of considering the influence of surcharge loadings on the active or passive side of the retaining structure. When analyzing such cases in practice, the proposed method gives results which are in better agreement with the results of FEM based elasto-plastic interaction analyses than with the results of currently used methods. At the same time, its results are in accordance with those published for homogeneaus cohesionless ground. Since in practice almost all retaining structures are erected in layered ground (heterogeneaus above the dredge level and homogeneous below it), the proposed method is very convenient and applicable for the analyses and design of cantilever structures under arbitrary geomechanical conditions.
Keywords: geomechanics, soil-structure interaction, retaining walls, embedment, cantilevers, earth pressure, pressure distribution, friction soil - wall, limit analysis, shear forces
Published in DKUM: 17.05.2018; Views: 1460; Downloads: 90
Full text (411,22 KB)
This document has many files! More... |
