Large-Scale Reinforced Clay Walls Backfilled with Clay at Cheng Kung University - Reinforced Soil Engineering: Advances in Research and Practice - page 191

Figure 6 Clod size distribution of the ready-for-use clay.

in which, c, fare the cohesion and internal friction angle of soil; l i is the length of
the slice base; W i is the self-weight of slice no. i; r u [

(u i b i /W i ] is the pore
pressure ratio defined by Bishop (1955); u i is the pore pressure acting on
the base of slice no. i; T i is the reinforcement force (tension) acting on the base of
slice no. i.
A total of 12 cases was investigated. The input parameters and the
analytical results are summarized in Table 4. The predicted failure surfaces
are also shown in Fig. 7 . In cases 1-A through 2-C, the strength parameters
for the aforementioned in-laboratory and in-situ soil specimens were used.
Note that in these cases the internal friction angles obtained in the triaxial
compression tests were multiplied by a factor of 1.1 to simulate the plane-
strain condition. In cases 3-A through 4-C, the cohesion of the clay was
neglected purposely. Table 5 shows that the cohesion of the compacted clay
dominates the stability the clay wall. It also showed that using the tensile
strength at 10% of strain, that is, using F T ¼

¼

3.3 on the ultimate strength

(T i ¼ 5.37 kN/m; see Fig.3) of the geogrid, or using a pore pressure ratio r u

¼ 0.1 yielded relatively small reduction in F s for cases 1-A through 2-C.

However, they yielded relatively large reductions for cases 3-A through 4-C
in which the cohesion of clay was not considered.