Recent Experiences of Reinforced Soil Retaining Structures in China - Reinforced Soil Engineering: Advances in Research and Practice - page 164

with Rankine's failure surface, namely,

u cr ¼ 45 8 þ f = 2 ð 2 Þ

In the cases of reinforcing materials B and A, the failure surfaces, like in
that of material C, consist of two planes as well. However, the upper plane is not
vertical. The stiffer the reinforcing material is, the more u 2 tends to 90 8 .
Based on these test results, a reasonable design method is suggested as
follows:

1. For the reinforced retaining wall with far low modulus of reinforcing
material, it may be designed using Rankine's theory.
2. For the reinforced retaining wall with a stiff element, it may be
assumed that the failure surface consists of two planes. The lower plane
is

in conformity with Rankine's rupture plane in which

2, and the upper one is a vertical plane in which
the distance from the failure surface to the front facing is 0.3H.
3. For the reinforced retaining wall with moderate modulus, the lower
plane of failure surface is the same as in 2 above, and the inclination
angle of upper plane is (45

u 1 ¼ u cr ¼ 45 8 þ f =

. Here H 1 is the height of
the turning point on the failure surface. Then the force equilibrium for
upper and lower parts of reinforced earth blocks can be used for
calculations, and u 2 , H 1 , and the maximum extension of reinforcing
element T max could be obtained by iteration (Lin Yuanzhi and Wang
Zhenghong, 1996).

8 þ f/2) # u 2 ?90 8

2.3 Tests of Fiber-Reinforced Cohesive Soil

In the 1970s Texsol was researched in France, and then it was used in reinforced
steep slopes, retaining walls, and embankments. The three-dimensional randomly
distributed continuous fiber-reinforced sand has some advantages in construction,
economy, and geotechnical and environmental prosperity. On the other hand, in
the practical engineering located in the places short of sand and in some hydraulic
engineering, the fiber-reinforced cohesive soil probably will be a kind of useful
and economical new material.
A series of tests on fiber-reinforced cohesive soil has been done including
drained and undrained triaxial tests, uniaxial extension test, fracture toughness
test, thick-wall cylinder test, and hydraulic fracturing test. These tests have
indicated that the fiber reinforcement significantly improves geotechnical
properties of cohesive soil and increases the plasticity and toughness of soil. The
following conclusions can be drawn: