Unit Cell Testing of Reinforced Soils - Reinforced Soil Engineering: Advances in Research and Practice - page 37

Figure 1 Mohr circle for unreinforced and reinforced soils.

study. The test results showed that the strength of reinforced sand increased with
confining pressure, s 3c : However, beyond a critical value of confining stress, the

strength of a reinforced specimen was controlled by the rupture strength of
reinforcement, and thus, the slope of the failure line for the reinforced specimen
was parallel to that of the unreinforced soil (Fig. 2a) . Based on this consideration,
they put forward a theory for the mechanism of soil reinforcement.
By giving a term, Ds 1 ; in addition to the strength offered by unreinforced

specimen, K p s 3 ;

the following relationship can be obtained for the strength of
reinforced soil specimen:
s 1 ¼ K p s 3 þ Ds 1

ð Þ

1

sin f 0 Þ=ð sin f 0 Þ

where K p ¼ð 1 þ 1 2 is the coefficient of passive lateral earth

pressure.
By relating the above equation to the Rankine equation for a cohesive-
frictional soil, that is,

K p c 0 s 1 ¼ K p s 3 þ

2 ð 2 Þ

the cohesion is obtained as

Ds 1

c 0 ¼

p

K p

ð 3 Þ

2

With the aid of the force diagram in which the failure plane is inclined at an
angle ato the horizontal (Fig. 2b), the following equation is obtained:

s 3 A tan a s 1 A tan f 0 Þ F þ ¼ ð a 2 ð 4 Þ