Geosynthetic Reinforcement in the Mitigation of Pipeline Flotation - Reinforced Soil Engineering: Advances in Research and Practice - page 235

Figure 3 Installation of geogrid.

Test 2. In this model, because the backfill soil was confined by the geogrid,
additional resistance to flotation was expected. The pipe floated when the
overburden height was reduced to 20 cm. The failure surfaces as
observed were similar to those of test 1. The speed of flotation was
smaller than that of test 1.
Test 3. The resistance of pipeline to flotation was enhanced by the use of
gravel and geogrid. The pipe floated when the overburden height was
reduced to zero. The cracks along the longitudinal direction of the pipe
developed in a manner different from tests 1 and 2. The cracks were
observed along the boundaries between the gravel and original
foundation. The grid floated with the surrounding gravel. The speed of
flotation was smaller than the previous two tests.
Test 4. The soil cement, 30 cm thick, was placed on the geogrid along its
length. The flotation was observed when the thickness of the overburden
soil layer was equal to zero. The effect of mitigation was similar to test 3,
where gravel was used with geogrid.