Retaining structures are of great importance in maintaining soil stability and have been in use for several decades. Some types of structures have performed very well in the vast majority of cases. In recent years, gravity retaining walls (GWs) built with prefabricated concrete units are becoming a popular solution for soil retaining system due to their low cost and convenient construction. However, the limitation for this kind of wall is that they cannot be built to a large height without any improvement, so they are usually combined with soil reinforcement (e.g. geogrid, geomembrane) to build such high earth retaining structures as geosynthetic reinforced soil walls (RSWs).

Crib block walls are a form of gravity retaining walls using prefabricated interlocking concrete units,...[ Read more ]

Retaining structures are of great importance in maintaining soil stability and have been in use for several decades. Some types of structures have performed very well in the vast majority of cases. In recent years, gravity retaining walls (GWs) built with prefabricated concrete units are becoming a popular solution for soil retaining system due to their low cost and convenient construction. However, the limitation for this kind of wall is that they cannot be built to a large height without any improvement, so they are usually combined with soil reinforcement (e.g. geogrid, geomembrane) to build such high earth retaining structures as geosynthetic reinforced soil walls (RSWs).

Crib block walls are a form of gravity retaining walls using prefabricated interlocking concrete units, such as modular headers and stretchers, to establish a framework of the structure. Since early 1980, crib block retaining walls have been popular in Hong Kong; however, the crib system is not popular in recent years. There are two reasons for this phenomenon. First, some other retaining structures perform better than crib walls, such as geocell wall and gabion wall. Second, due to the rapid development of science and technology, interchange and viaduct are widely used in recent years, and this technology limits the use of crib walls. Furthermore, considerable studies have paid attention to the performance of different retaining walls from various aspects, such as different backfills, heights, widths, facing angles, reinforcements, etc. but not to improving the performance of crib block retaining walls. Therefore, this study intends to propose new designs to improve the performance of crib walls through experimental and numerical studies. It is hoped that the experimental results will provide a valuable reference for engineering projects.

The experimental study was based on small-scale tests. In order to conduct feasible small-scale experiments and centrifugal tests, which demand the prefabrication of experimental models meeting the scaling requirements on geometrical and mechanical properties, 3D-printing technology was employed as a necessary tool of this research work. A numerical platform OptumG2 was applied in the numerical study. Limit analysis and elastoplastic multiplier analysis were performed. In the limit analysis, the surcharge on the top of the backfill is increased gradually until the collapse of the structure occurs. The deformation of the models during the incremental load process is calculated using the elastoplastic multiplier analysis.

From the experimental and numerical simulations, it was found that inclined walls performed better than vertical walls, and the stability of the structure could be greatly improved by installing reinforcements. It was also shown that the shear key can reduce the lateral displacement significantly by 50%, and is suggested for new crib designs.