ABSTRACT
The paper describes some experiences about the use of HDD methodologies for consolidation and ground improvement in underground constructions. Traditional vertical or subvertical drilling sometimes become problematic for the presence of streets, sewers, underground utilities, existing buildings or for the particular shape of soil improvement. These obstacles constraints the executive choices. The possibility of using horizontal drillings, especially if directional, with the possibility to correct planimetric and altimetric model, makes free the imagination of the designer, who could experiments new applications. HDD technique makes possible to place T.A.M. (“Tube A Manchette”). The possibility to execute directional coring, with HDC (Horizontal Directional Coring), makes possible to carry out geotechnical (geognostic) surveys, also for tests in the hole: so we can have like a little pilot tunnel for geotechnical or in general drilling information. Finally the paper describes the field test, and the positive results of jet grouting consolidation performed by HDD technique.
