Optimization of sensors locations in internal stability analysis of Geosynthetic-reinforced earth retaining walls

This paper concerns the optimization of sensors locations used to monitor the geosynthetic reinforcement internal forces of a reinforced earth retaining walls. The internal stability analysis of these structures is addressed through the kinematic theorem of limit analysis combined with the discretization technique to generate the failure surface. Knowing that the majority of damages of these structures are caused by the water presence in the reinforced zone, different water table levels are considered in the study and their effects on the critical failure surface location are analyzed.

Seismic internal stability assessment of geosynthetic reinforced earth retaining wall in cohesive soil using limit analysis

Assessment of internal seismic stability of geosynthetic reinforced cohesive soil retaining walls with likelihood for developing cracks in the failure mechanism is typically done with the limit equilibrium method. However, in this paper, the kinematic theorem of limit analysis combined with the discretization method are used to implement the crack formation in the collapse mechanism in the internal seismic assessment of geosynthetic reinforced soil retaining walls within the framework of the pseudo-static approach. The presence of the crack leads to an increase of the required reinforcement strength that prevent the failure of the structure.

Three-dimensional displacement analysis of slopes subjected to seismic loads

Seismic excitation is among the many possible factors contributing to slope failures. Typical design of slopes and analyses of existing slopes are carried out assuming plane strain mechanisms of deformation, and replacing the seismic loading with a uniformly distributed static force. A three-dimensional (3D) analysis of slopes is described in this paper, based on the kinematic theorem of limit analysis. Critical acceleration is calculated for 3D slope failures, and an analysis of a rotating block is executed to develop a solution for displacements of slopes subjected to seismic shaking. The emphasis is more on applying the displacement analysis to a 3D collapse pattern, and less on the choice of ground motion records suitable for the 3D failure analysis of slopes. The analysis is applicable to slopes for which the geometry of the failure pattern is physically confined, as for instance, in the case of excavations. A 3D failure pattern is then expected, and the results of calculations are given for a reasonable range of the width-to-slope-height ratios. The method is illustrated with practical examples.

Analysis of Face Stability during Excavation of Double-O-Tube Shield Tunnel

This paper focuses on the face stability analysis of Double-O-Tube shield tunnel. This kind of analysis is significant to ensure the safety of workers and reduce the influence on the surrounding environment. The key point of the stability analysis is to determine the supporting pressure applied to the face by the shield. A collapse failure will occur when the supporting pressure is not sufficient to prevent the movement of the soil mass towards the tunnel. A three-dimensional collapse failure mechanism was presented in this paper. Based on the mechanism of a single circular shield tunnel, the mechanism of Double-O-Tube shield tunnel was established by using the fact that both of the mechanisms are symmetrical. Then by means of the kinematic theorem of limit analysis, the numerical results were obtained, and a design chart was provided. The finite difference software FLAC3D was applied to investigate the face failure mechanism of DOT shield tunnel established in this paper; the critical supporting pressures of the collapse failure mechanism in different strata (sand and silt) were calculated. Through comparative analysis, the theoretical values were very close to the numerical values. This shows that the face failure mechanism of DOT shield tunnel is reasonable, and it can be applied to the sand and silt strata.

Determination of the limit load of statically indeterminate truss girders

The paper presents the procedure of limit load calculation of elasto-plastic trusses exposed to the action of proportional load which is gradually increased until the formation of failure mechanism. The calculation is based on the application of static and kinematic theorem of limit analysis which are the basis of the limit analysis of structures which produce the value of the limit load in a quick and efficient manner. Application of these theorems is displayed on the examples of truss girders loaded by one- and twoparameter load.

A reduced form of shakedown kinematic theorem

A reduced form of the shakedown kinematic theorem without time integrals is deduced for Tresca material, which is equivalent to the original one when the principal directions of plastic deformations everywhere in a structure remain unchanged during loading cycles.

On Some Issues in Shakedown Analysis

Shakedown analysis, and its more classical special case of limit analysis, basically consists of “direct” (as distinct from time-stepping) methods apt to assess safety factors for variable repeated external actions and procedures which provide upper bounds on history-dependent quantities. The issues reviewed and briefly discussed herein are: some recent engineering-oriented and cost-effective methods resting on Koiter’s kinematic theorem and applied to periodic heterogeneous media; recent extensions (after the earlier ones to dynamics and creep) to another area characterized by time derivatives, namely poroplasticity of fluid-saturated porous media. Links with some classical or more consolidated direct methods are pointed out.