It has already been shown that the stability of the geotextile reiforced earth walls was improved with the use of rigid facings that brought about the reduction of overall deformation and the amount of tensile force generated in geotextile. To evaluate the effects of facing rigidity, stress-deformation behavior must be analyzed based on the interaction of facings, geotextiles, and soils.A numerical analysis using a two-dimensional elasto-plastic FEM taken account of the construction process was conducted to clarify various aspects of the behavior of a reinforced earth walls measuring 10.0m high. Three types of facings were analyzed: the wrapped-around wall face method, the concrete panel face method, the concrete block face method. In addition, the slope of wall was varied from 1:0.0 to 1:0.8 (pitch of 0.2). The results showed that facings performed using the block and panel face method, which provided higher rigidity than the wrapped-around wall face method, could be increased the stability of the reinforced earth walls under the characteristic bound coditions be satisfied:
This paper presents an experimental study on the performance of 6m high grid reinforced embankments, subjected to additional loading after construction. Additinal loading was applied by a surcharge of a 3m high filling, then submerging the structure in water, then rapidly lowering the water level outside the embankment.The embankments were constructed with 1:1 slope using silty sand and instruments were used to monitor the deformation of the embankments as well as strain levels in the polymer grids.On the basis of the mesured grid strain distribution during loading, the current design methods, such as the limit equilibirium method, and the critical safety factor where the reinforcement strains largely increase, were evaluated.
In order to study the effect of plastic material on the bearing capacity of superficial foundation, a series of bearing tests on reinforced soils by plastic materials were carried out. A small scale reproduction experimentation was madein laboratory, on Taylor-Scheneebeli analogicalmaterial that responds to Coulomb critirion. The influence of a big number of experimental parameters on soil bearing was observed such as the plastic quantity by layer, geometrical form of the plastic pieces, the depth of the first layer, layers number, the distance between layers and the way the continuous layers are fixed.
This article described experiments undertaken to: (a) evaluate the effects of polymer grid reinforcement upon the strength and stability of an embankment; and (b) evaluate a design procedure and construction technique for such grid reinforced embankments. A full scale grid model embankment with the following parameters was constructed and tested to failure by changing its slope: (height: 14 m; base width 55 m; slope 1:0.5 up to a height of 6 m and 1:0.8 from 6 m to 14 m). One section of this embankment was not reinforced, and the other 4 sections were reinforced with different amounts (one or two layers) or patterns (chequered or laid in a continuous strip) of grid. The dynamic behaviour of the embankment sections were studied and measurements taken of: the grid and fill material strains; the relative horizontal displacement of the fill material from the slope; and the settlement and horizontal displacement of the embankment. The data obtained were analysed by the finite element method (fem), and the effects of the reinforcement evaluated. Computer simulation of embankment failure using fem was also carried out. The computed results agreed closely with the measured data. The results also showed that embankment strength increased and deformation decreased with increasing reinforcement. The chequered pattern of grid reinforcement was found to be most effective. For the covering abstract of the symposium see IRRD 818063.
This paper proposes a slope stability analysis method considering progressive failure based on the limit equilibrium principle. The softening of soil is taken into account and the slip surface of arbitary shape is adopted.Formulation of the ploblem is carried out by using the slice method, and the analysis satisfies both force and moment equilibrium conditions. The basic idea of the proposed method is to define a local factor of safety at the base of each slice. Thus, the number of unknowns increases, and the ploblem becomes more highly undeterminate than those in the conventional slice methods. In order to render the ploblem determi-nate, two simplifying assumptions about the interslice forces and the line of thrust are simultaniously made which are separatly used in the Morgenstern-Price method and the Janbu method. An overall factor of safety is introduced to evaluate the whole stability of a slope. Finally, the results of an example problem show that the proposed analysis method can reasonably represent the actual behavior of the progressive failure of cl Slopes.
A series of testings on earth embankments had been conducted with a view to formulate a rational design as well as a proper construction technique of polymer grid reinforced embankment. In practice experimental embankments (height 3m, slope 1:0.7) were constructed laying in the earth-fill polymer grids at various lengths and at various spacings in the vertical direction. Tests were also done for both cases of embankment with and without slope protection measures. A comparative studies of grid reinforcing effect was carried out by conducting tests on embankments under heavy rain (reinfall intensity 15mm/hr) and reinforcing effects of grids as a result of integration of earth and grid was under special scrutiny. In this report a summary of test results were described. The FEM analysis based on elasto-plastic models was performed using these results. It was confirmed that models simulate the actual conditions of practical construction.
A full scale embankment (height 6.25m, front slope 1:0.2, fill material: dry sand) is constructed by reinforcing with geogrids and these are successively disconnected by passing electricity through the nichrome wire which are intertwined in advance. With the decrease of the number of reinforcing grids the embankment gradually loses the stability and finally collapses when all the grids are disconnected.In the present research the fracture behaviors of the embankment are observed at every stage of grid-disconnection and the analysis on fracture phenomenon is conducted by the conventional limit equilibrium method. It was learnt that the effects of the pseudo retaining wall (width 70cm) formed by the pile of sandbags sandwiched by geogrids on the front slope is required to be taken into consideration in the stability analysis of the embankment. In that the collapse-phenomenon of the embankment without reinforcement is fully explained and understood as a result of the study.
