**4. Conclusions**

**3. Comparison of measurements and prediction of tension in** 

be determined by Eq. (1). In this equation, the terms ff

Td <sup>=</sup> <sup>T</sup> \_\_\_\_\_\_ ult

damage that may occur during installation.

<sup>d</sup> = mechanical damage reduction factor;

The basic concept of internal design includes analysis of failure of reinforcement, i.e., it is to verify if the maximum calculated load in the reinforcement (Tmax) using appropriated method is lower than the design load of the selected reinforcement (Td). In addition, verification against pullout failure must be done. The design should provide enough length of the reinforcement in the resistance zone (beyond the potential failure surface) to avoid pullout failure. The design strength Td is estimated at the end of a given reference time (service life) for a particular installation environment and damage that may occur during installation. Td can

dependent of the type of fabric, the service life, the particular installation environment, and

Tult = ultimate tensile strength, i.e., tensile resistance in short-term resistance obtained from the

**Table 5** shows the values of Td and the reduction factors for the installation conditions and geogrids used in the presented wall (see **Table 3**). The reduction values were evaluated considering that: PET geogrid was used as reinforcement; the design service life is 120 years; the pH of residual lateritic soils is around 5 (installation environment); and low damage during geogrid installation (0.30-m thick backfill layers of fine-grained soil and roller drum Dynapac CA250PD). Moreover, in all reinforcement layers, the values of Td must be higher than Tmax

**Figure 14** shows comparison of measured and calculated load in reinforcements. The determination of maximum load in the reinforcement layers was done using the analytical method presented by Ehrlich and Mitchell [4]. Through this method, backfill shear resistance,

**Geogrid Tult (kN/m) ff fd fa Td (kN/m)** 1–3 55 1.67 1.05 1.1 28.5 4–7 35 1.67 1.05 1.1 18.1

**Table 5.** Reduction factors, Tult and Td values for the fabrics (geogrids) used in the design of the wall.

wide-width tensile strength test (the nominal resistance of the geosynthetic);

<sup>a</sup> = reduction factor for chemical and environmental damages.

considering an appropriated factor of safety (FS ≥ 1.5).

ff ∙ fd ∙ fa

, fd, and fa

are reduction factors that are

(1)

**reinforcements**

104 Engineered Fabrics

where

<sup>f</sup> = creep reduction factor;

f

f

f

The mechanical behavior of reinforced soil wall built with fabrics (geogrids) is presented based on results of a well-instrumented wall. In this concrete-block-face reinforced wall, tropical fine-grained soils were used as backfill, and two type of fabrics were used as reinforcement. This wall was constructed in 2006 and presents good performance without any structural problem or excessive deformation until nowadays.

Measurements and calculated values of tensions in the reinforcements using an analytical method [4] were compared. Good prediction capability of the used method was verified. In accordance to the good performance of the wall, measurements indicate low vertical and lateral movements, and the mobilized load in the reinforcements was lower than the design load. Measurements also indicate that the block-face supported part of the load that would be carried by the reinforcements.

The fabrics used in the construction were capable to resist the efforts imposed by the structure. The measured mobilized tensions on fabrics (Tmax) were lower than the design strength (Td). Considering that Td is the maximum tension that can act on fabric (Td is a portion of Tult), it is observed that the wall has safety in terms of internal stability.

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