Study on PFF composite filter layer and its application in retaining engineering

In order to avoid the adverse effects of water on retaining structure, filter layer is needed to set under the retaining structure. The construction materials of retaining structure was changed from mortar rubble to concrete, then the construction method was also changed from masonry to cast-in-place concrete. Due to the narrow space, it is difficult to guarantee the quality and the compaction degree of the conventional sand gravel filter layer, thus the reliability of the retaining structure was affected. Base on the basic principle of the filter layer, such as isolation, filtration and drainage, a new type of geosynthetics filter layer is developed. The new filter layer, which possesses formwork feature, is formed by the combination of water-resisting layer, drainage layer and permeable layer. The efficiency of concrete retaining wall construction is significantly improved after using this new material. Site drainage test shows that discharge water quantity and efficiency of the new filter layer are better than the traditional sand gravel filter layer, which can be used in retaining engineering.