Innovative Methods to Improve Stability in Dumps and to Enlarge of Their Capacity

An important reason for the existence of bank slides in natural terrains or in engineered dam excavations is that the water banks up and destroys engineered installations and soil by excessive moisturisation. The problem is usually solved by building drainage facilities – vertical filtration wells, horizontal segments and drill holes. The wells and segments have several major disadvantages. The vertical drill holes have a limited effective radius. This requires small spacings in-between, a large volume and expensive drilling work. Horizontal drillings require an initial shaft or a protective ditch for the drilling equipment, which is difficult to lay and is limited to drainage pipes of a maximum length of 100–150 m. To avoid the shortfalls of the filtration and drainage installations mentioned above the method HDD has been devised and introduced. In Germany, more than 15%-18% of the cable, pipe and filtration networks that may vary in type and purpose are installed without excavations (1). This is the so-called “Subsoil Revolution”.