Limit analysis of cohesive slopes reinforced with geotextiles

2021

Reinforced soil slopes are widely used in civil engineering for slope protection for their vast advantages. The paper reports the details of numerical models used to predict the factors affecting force distribution in the reinforcement layers of reinforced slope-instrumented structures. However, the failure mechanism of reinforced slopes has not been fully studied. The stability analysis of reinforced slopes is conducted in this paper based on the limit equilibrium method. Furthermore, the effects of the target factor of safety and the soil friction angle of the reinforcement layers on the reinforcement force distribution are investigated. The research results indicate that the above parameters have great effects on the maximum reinforcement force and the reinforcement force distribution of the reinforced slope. Based on the analysis of computation results, the reinforcement mechanism is analyzed and the optimum design scheme of the reinforced slope is recommended. The results can b...

Geotechnical and Geological Engineering, 1992

A procedure for the stability analysis and design of geosynthetic reinforced soil slopes over a firm foundation is described. Firstly the unreinforced slope is analysed, and for this a circular failure method is used which allows a surcharge load to be taken into account. Any method of slip circle analysis could be used to identify the coordinates of the centre of the slip circle, its radius and the minimum factor of safety. In this study, both internal and external stability analysis of the reinforced slope is presented. Internal stability deals with the resistance to pullout failure within the reinforced soil zone resulting from the soil/reinforcement interaction. The external stability is considered by an extension of the bilinear wedge method which allows a slip plane to propagate horizontally along a reinforcing sheet. The results for total tensile force, internal and external stability are presented in the form of charts. For given properties of soil and slope geometry, the required strength of the geosynthetic and the length of reinforcement at the top and bottom of the slope can be determined using these charts. The results are compared with the published design charts by Schmertmann et al. (1987).

… of the Tenth International Conference on …, 2000

Innovative Infrastructure Solutions, 2020

This paper presents both experimental and numerical studies of three-layered reinforced soil slopes consisting of one sandy layer sandwiched between two cohesive-frictional soils. Geosynthetic reinforcements are provided at the interfaces. Smallscale shaking table tests are performed to evaluate different stability parameters like horizontal deformation, root-mean-square acceleration amplification factor, and crest deformation of the slope. Water content, base shaking acceleration, frequencies, and quantity and type of reinforcements are varied to perform the tests. The inclusion of reinforcements increases the strength of the slope enormously which is represented in the paper in terms of different parameters. Geogrid reinforcement is found to be better in comparison with geotextile reinforcement. To verify the results obtained from the present experimental study, a numerical model is developed using PLAXIS 2D and the acceptability of the study is discussed.

Geosynthetics International, 2012

Numerical methods combined with centrifuge tests are used to investigate the distribution and development of soil stresses and reinforcement tensile loads in geosyntheticreinforced soil (GRS) structures. In this study, system stability indicated by the factor of safety (FS) of GRS slopes is calculated by limit equilibrium analysis. Stress information under various stress states is evaluated using finite element analysis. Advanced models and an integration algorithm are implemented in finite element code to enhance the simulation results. The proposed numerical models are validated by centrifuge tests of two GRS slopes with different backfill densities. Numerical results indicate that soil stress mobilisation can be described by the soil stress level S, which is defined as the ratio of the current stress status to peak failure criteria. For both slope models, as loading increases, backfill stresses develop and propagate along the potential failure surface. Mobilisation of soil stress was non-uniform along the failure surface. Immediately after the stress level reaches peak (S ¼ 1), strength softening initiates at the top and toe of the slope at approximately FS ¼ 1.2. The slope settlement rate and reinforcement tensile load increase significantly when soil softening begins. The softening occurs randomly and irregularly along the failure surface, and the formation of the soil-softening band completes at approximately FS ¼ 1.1. The failure surface corresponds to the locus of intense soil strains and the maximum tensile loads at each reinforcement layer. Additionally, the numerical results show that the initiation of soil softening and the failure of the slope occurred earlier in the slope model with low backfill density. The numerical results support the view that peak shear strength, not residual shear strength, governs system stability. Last, the distribution of maximum reinforcement tensile loads with depth was highly uniform at low g-level and became trapezoidal at high g-level. The peak value was located at approximately mid-height of the reinforced slopes. This observation contradicted the triangular distribution with depth assumed in current design methodologies for geosynthetic structures.

Geotextiles and Geomembranes, 2019

Although a cohesionless backfill is recommended for geosynthetic reinforced earth retaining walls, cohesive soil have been widely used in many regions across the globe for economic reasons. This type of backfill exposes the soil to the crack formation that leads to reduce the stability of the system. In this paper, to investigate the internal seismic stability of reinforced earth retaining walls with cracks, the discretization method combined with the upper bound theorem of limit analysis are used. The potential failure mechanism is generated using the point-to-point method. Two types of cracks are considered, a pre-existing crack and a crack formation as a part of the failure mechanism. The use of the discretization method allows the consideration of the vertical spatial variability of the soil properties. A pseudo-dynamic approach is implemented which allows the account of the dynamic characteristics of the ground shaking. The presented method is validated using the conventional limit analysis results of an existing study conducted under static conditions. Once the proposed technique to consider the cracks is validated, a parametric study is conducted to highlight the key parameters effects on the lower bound of the required reinforcement strength.

American Society of Civil Engineers, 2024

A method to assess the influence of tension cracks on the seismic external stability analysis of geosynthetic-reinforced soil slopes is carried out in the present study. In addition to being subjected to uniform surcharge loading, hydrostatic and hydrodynamic pressures with water on both sides of the c-ϕ soil slope and seismic inertia forces are considered, and the reinforcement length for both sliding and overturning conditions is evaluated by using a two-part wedge mechanism. The analysis is implemented separately by considering and neglecting the effect of the formation of tension cracks, and reinforcement lengths are evaluated for both the slope angles 60° and 70°. It is seen that when the horizontal seismic acceleration coefficient increases from 0 to 0.2 for a 60° slope angle under the direct sliding mode of failure for a particular set of input parameters as shown in Table 3, the required minimum length of the geosynthetic reinforcement increases from 0.59H to 1.30H, and in the overturning mode, it increases from 0.46H to 0.60H, when the analysis is implemented without considering similar tension cracks when tension cracks are considered in the study, for the increases in kh, as mentioned previously, required minimum length of the geosynthetic reinforcement against direct sliding mode of failure increases from 0.80Hto 1.67H, and increases from 0.55Hto 0.64Hfor overturning mode of failure. In addition to kh, the influence of the height of water on the downstream side, pore pressure ratio, soil friction angle, cohesion, and surcharge on the length of reinforcement against sliding and overturning modes of failure are presented in this paper in the form of design charts. The results obtained from the present study are compared with the previous literatures and usefulness of the present method in analysis of reinforced soil slopes against direct sliding and overturning modes of failure has been proposed

Geotextiles and Geomembranes, 1991

Applied Sciences, 2021

This research investigated the effects of types of cohesive-frictional soil and geotextile reinforcement configurations on the bearing capacity of reinforced soil foundation (RSF) structures, via laboratory test and numerical simulation. The four reinforcement configurations studied for the RSF included: (i) horizontal planar form of geotextile, (ii) full-wraparound ends of geotextile, (iii) full-wraparound ends of geotextile with filled-in sand, and (iv) full-wraparound ends of geotextile with filled-in sand and sand backfill. The foundation soils studied were mixtures of fine sand and sodium bentonite at replacement ratios of 0, 20, 40, 60, 80, and 100% by dry weight of sand to have various values of plasticity index (PI). The numerical analysis of RSF structures was performed using PLAXIS 2D software. Several factors were studied, which included: embedment depth of the top reinforcement layer (U), width of horizontal planar form of the reinforcement (W), and spacing between geote...

2004

This Paper outlines the Finite Element Method of analysis for simulating of Geosynthetic-Reinforced Soil Retaining Walls (GRS-RWs). Results of a parametric study to investigate the effect of facing including panel facing, segmental facing and wrapped facing on the behavior of GRS-RWs in terms of displacement of wall and forces in the reinforcements are presented. However this study is focused on the walls, because of the similarities to other forms of reinforced structures in facing such as slopes and abutments it can be applied to these structures too. This study shows that facing has a strong effect especially on the displacement of walls and should be taken into account in the design procedures which is not often concerned in analysis. RÉSUMÉ Ce Papier esquisse la Méthode d'Elément Finie d'analyse pour simulers de Murs De Soutènement de Sol GeosyntheticRenforcés (GRS-RWs). Les résultats d'une étude paramétrique pour examiner l'effet de revêtement y compris le pann...