Issue and Nonissue in Block Walls as Implied Through Computer-Aided Design - Reinforced Soil Engineering: Advances in Research and Practice - page 86

Table 3 Connection Safety Factors for Geosynthetic Block Wall in Table 2

Connection
force, to
(kN/m)

Elevation
(m)

L
(m)

Connection
break, Fs

Connection
pullout, Fs

Geosynthetic
break, Fs CR u CR s

0.375 5.50 31.6 0.90 0.45 1.49 1.62 1.50

1.125 5.50 28.6 0.90 0.40 1.64 1.61 1.66

1.875 5.50 25.6 0.90 0.36 1.84 1.60 1.86

2.625 5.50 22.6 0.90 0.31 2.08 1.58 2.10

3.375 5.50 19.6 0.90 0.27 2.40 1.56 2.42

4.125 5.50 16.6 0.90 0.22 2.83 1.52 2.86

4.875 5.50 13.7 0.90 0.18 3.45 1.48 ( , 1.50) 3.48

5.625 5.50 10.7 0.90 0.13 4.41 1.41 ( , 1.50) 4.46

6.375 5.50 7.7 0.90 0.09 6.13 1.28 ( , 1.50) 6.19

7.125 5.50 5.7 0.90 0.04 8.22 0.81 ( , 1.50) 8.31

Note: T ult ¼ 115 kN/m, RF d ¼ 1.1, RF id ¼ 1.1, RF c ¼ 2.0, CR u ¼ 0.9, CR s varies linearly between 0
and 0.9 as blocks confining pressure varies from 0 to 360 kPa; blocks are 20 cm high with average unit
weight of 24 kN/m 3 .

Table 2 indicates that such large spacing creates no pullout problem, Table 3
shows that connection pullout, especially in upper layers, is a potential problem.
Clearly, the calculated Fs for connection break indicate that weaker
reinforcement would present a problem as well, albeit at the lower layers. It
should be pointed that the connection pullout results are very sensitive to the
value of CRs.
Figure 3a shows more realistic layer spacing; i.e., 40 cm apart, 20 layers in
total. Table 4 corresponds to this spacing; however, unlike the previous case, it
uses a realistic geosynthetic with T ult ¼ 65 kN/m. All other design parameters

remain the same. While connection break has improved, layers in the upper 2m
possess low Fs for connection pullout (in the previous case, Table 3, layers in the
upper 3m were deficient in terms of connection pullout). While reducing the
tributary area of reinforcement results in smaller connection loads, the problem of
insufficient connection strength may still exist, especially at upper layers where
confinement provided by the stacked blocks is low.

4 REMEDY (FOR POLYMERIC REINFORCEMENT)

Closely spaced geosynthetic layers (say, every block) significantly reduce the
tributary area and thus the connection load. At increments of one block spacing,
the problem of

insufficient connection strength might be alleviated.