Anti-filtration and drainage of geomaterials

When there is seepage in the soil, it is often accompanied by seepage deformation, such as piping and flowing soil. This should be paid attention to in the excavation of embankments and foundation pits. On the one hand, the hydraulic gradient can be reduced by means of anti-seepage, precipitation or increasing the seepage diameter, and on the other hand, the seepage flow can pass smoothly and a reverse filter layer is set at the outlet to prevent soil erosion. Grain loss, such cases include drainage consolidation of soft soil foundations and other underground drainage facilities.

Different products of geosynthetics have good drainage and reverse filtration (percolation or filtration) functions, so they can replace traditional sand and gravel to build drainage and filtration structures. When the geotextile is in contact with the soil and there is seepage, the drainage and filtration effects of the geotextile are two inseparable and coexisting functions. When water seeps out of the soil and flows into the geotextile, the geotextile must not only drain the amount of infiltrated water, but also protect the soil from harmful seepage deformation. Therefore, drainage and reverse filtration are often contradictory. For example, for the pore size of the filter layer, it is better to have a larger pore size in terms of drainage, but it may be more appropriate to want it to be smaller in terms of reverse filtration.