Large-Scale Reinforced Clay Walls Backfilled with Clay at Cheng Kung University - Reinforced Soil Engineering: Advances in Research and Practice - page 202

respectively. The deformation of the wall facing might be a result of the
following three mechanisms:
1. Swelling of the soil at the vicinity of facing
2. Water pressure in the tension cracks or shear bands behind the
reinforced zone
3. Creep at the soil -reinforcement interface
Because only small and localized cracks parallel to the facing were
observed during dismantling of the walls, mechanisms (1) and (3) were most
likely to govern the deformation of NCKU walls.
7 TEST RESULTS FOR EMBANKMENT
Infiltration tests were performed on the top of the 1.0-m-high embankment at the
center of each section using 300-mm-diameter single-ring infiltrometers
immediately after the completion of the embankment. The test arrangement is
schematically shown in Fig. 4 . The water height versus elapsed time relations
obtained in the infiltration tests are shown in Fig. 14a and b. It is seen that the
sections under dry-of-optimum compaction (Sections 1-A and 1-B) demonstrated
the highest infiltration rates, while those under wet-of-optimum compaction
(Sections 3-A and 3-B) showed inconsistent results; that is, Sections 2-A and 2-B
showed similar infiltration rates to those compacted under dry-of-optimum (1-A
and 1-B), while Sections 4-A and 4-B showed quite small infiltration rates. This
inferred that the permeability of clay mass compacted at OMC may vary
significantly because of the localized dry-of-optimum zones possibly induced by
nonuniform water spreading. The wet-of-optimum sections (3-A and 3-B)
consistently showed the lowest infiltration rates in two sides of test.
Relative degrees of compaction (R.C.) for Sections 1 through 4 are
summarized in Table 3 . It is seen that higher values of R.C. occurred in Sections 3
(about 3% wet-of-optimum), while smaller values of R.C occurred in Sections 2
(optimum water content). Smaller values of R.C. resulted in higher infiltration
rates as seen in Fig. 14a and b. For “wetter” conditions (i.e., Sections 3-B and
4-B), the B side demonstrated smaller infiltration rates than the A side. This may
be attributable to the soil confinement effect generated by the reinforcing sheets
during compaction.
The test embankment was dismantled by cutting through the center of the
sections vertically along the long axis of the embankment to measure the
distribution of water content on the vertical face of the embankment. A total of
600 samples was taken from eight sections on the vertically cut faces of the
embankment. Permeability coefficients at saturated conditions for undisturbed
samples from Section 3-A are summarized in Table 5 .