During construction of a tunnel there could be sections with very difficult ground conditions such as high water inflow and/or unstable fractured rock.
Under such circumstances it might be necessary to stabilize and seal the section to be excavated using different forepoling techniques such as pipe roofing or ground freezing.
In either case there is a need for casing advancing.
The water-powered Wassara DTH hammer is well suited for casing applications under severe conditions. High water flows will not interfere with its performance. Water will act as a lubricant for the casing making it possible to case longer holes.
When forepoling in fractured rock with high water content (like under seas, in high mountains etc.) there is a high probability of encountering high water flow at high pressure.
Drilling with the water-powered Wassara DTH hammer under these conditions will work fine since the hammer performance is not affected by high water flow at high pressure.
Forepoling in urban tunneling projects often face a risk of damaging buildings and nearby infrastructure due to settling. This risk is minimized with the water-powered Wassara
DTH hammer since it does not pressurize the formation in the way that for example air DTH drilling does.