Techniques for Determining Optimal Geotechnical Drilling Depth

Determining the optimal depth for geotechnical drilling involves balancing precision and practicality. Here are the main techniques used to decide the appropriate depth for subsurface investigations.

1. Preliminary Site Assessment

A site’s geological and topographical conditions guide initial decisions on drilling depth:

• Surface Surveys: Tools like ground-penetrating radar help identify subsurface features.

• Soil Sampling: A Borehole Sampling Machine can extract shallow samples to inform deeper investigations.

2. Layer Identification

Drilling must continue until all significant layers are identified:

• Topsoil and Fill Material: Typically shallow but must be assessed for stability.

• Load-Bearing Strata: Drilling extends to rock or dense soils capable of supporting loads, often requiring an Exploration Coring Drill Rig.

• Groundwater Table: Determined through borehole observations, it affects both design and construction.

3. Equipment Selection

Using the right equipment ensures efficient and effective drilling:

• Portable Full-Hydraulic Core Drilling Rig: Handles variable terrains and provides deeper penetration.

• Exploration Trenching Drill: Useful for exposing shallow strata quickly and economically.

4. Adherence to Standards

Engineering standards like Eurocode 7 specify depths for different project types:

• For shallow foundations, drilling 1-2 meters below the expected base is common.

• For deep foundations, depths of 20-30 meters may be required.

5. Site-Specific Adjustments

Field challenges such as hard rock layers or collapsing soils may necessitate adjustments:

• Hard Rock: Requires specialized coring rigs.

• Unstable Soils: Casing or mud rotary techniques stabilize the borehole.