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

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 be determined by Eq. (1). In this equation, the terms ff , fd, and fa are reduction factors that are dependent of the type of fabric, the service life, the particular installation environment, and damage that may occur during installation.

$$\mathbf{T}\_d = \frac{\mathbf{T}\_{\text{alt}}}{\mathbf{f}\_i \cdot \mathbf{f}\_d \cdot \mathbf{f}\_s} \tag{1}$$

reinforcement, and soil stiffness properties are considered, and the backfill compaction stresses are taken explicitly into account. The induced stress due to compaction has the effect of increasing the tension in the reinforcements and the soil cohesion reduced it. In the calculation, the nonconsideration of those factors may lead to poor prediction capability of the real

Behavior of Reinforced Soil Wall Built with Fabrics http://dx.doi.org/10.5772/intechopen.79239 105

**Figure 14** presents that measurements and calculated values of maximum load in the reinforcement (Tmax) are smaller than Td. These results also indicate that the predicted values are close to the measured ones, attesting the good performance of the method that was used in the analysis. Additional discussion about measurements and prediction, including determined

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

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

results using other methods found in the literature, is present in [6].

**Figure 14.** Comparison of Td and Tmax measurements and predictions.

structural problem or excessive deformation until nowadays.

behavior found in the field.

**4. Conclusions**

carried by the reinforcements.

where

Tult = ultimate tensile strength, i.e., tensile resistance in short-term resistance obtained from the wide-width tensile strength test (the nominal resistance of the geosynthetic);

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

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

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

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

**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,


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

**Figure 14.** Comparison of Td and Tmax measurements and predictions.

reinforcement, and soil stiffness properties are considered, and the backfill compaction stresses are taken explicitly into account. The induced stress due to compaction has the effect of increasing the tension in the reinforcements and the soil cohesion reduced it. In the calculation, the nonconsideration of those factors may lead to poor prediction capability of the real behavior found in the field.

**Figure 14** presents that measurements and calculated values of maximum load in the reinforcement (Tmax) are smaller than Td. These results also indicate that the predicted values are close to the measured ones, attesting the good performance of the method that was used in the analysis. Additional discussion about measurements and prediction, including determined results using other methods found in the literature, is present in [6].
