When planning the construction of tunnels, rock caverns and shafts, an extensive investigation of the rock formation in the area is required. The investigation is used to identify problematic ground and secure an efficient and low-risk construction.

Directional core drilling is an investigation method that allows core sampling along any defined trajectory, providing extremely accurate and relevant information about the rock formation near the planned underground construction.

By utilizing DCD, it is possible to steer the borehole along a predefined trajectory, no matter if it is curved or straight. With high accuracy, the borehole will follow the specified path, for instance parallel to a planned tunnel, while at the same time collecting a core sample.

With this approach, fault zones and fractures are drilled through in the same direction as the planned construction will hit them, giving relevant information about size, properties, material, leakage etc.

The core samples, both from the directional and standard drilling process, can be tested in a lab to reveal the mechanical properties of the rock. Further geophysical and hydrological tests can be performed in the completed borehole.

Some benefits of directional core drilling (DCD) are:

• High accuracy continuous core samples and geological information from the planned tunnel trajectory
• Data on the extent and orientation of problematic rock formations
• Information about the mechanical properties of the rock formations
• Basis to estimate groundwater inflow
• Basis to estimate stabilization measures
• Basis to estimate construction costs and duration