Development of deep-underground engineering structures via 2D and 3D RQD prediction using non-invasive CSAMT

Area of Science:

• Geotechnical Engineering
• Geophysics
• Rock Mechanics

Background:

• Accurate rock mass characterization is crucial for deep underground engineering.
• Rock Quality Designation (RQD) is a key geomechanical criterion for risk assessment.
• Traditional RQD estimation methods (drilling) are time-consuming, costly, and provide limited data.

Purpose of the Study:

• To present an innovative geophysical approach for 2D and 3D RQD estimation.
• To provide a faster, cheaper, and more accessible method for obtaining geomechanical volumetric data.
• To evaluate the feasibility of using non-invasive Controlled Source Audio-frequency Magnetotellurics (CSAMT) for RQD estimation at depths exceeding 1 km.

Main Methods:

• Utilized a non-invasive geophysical technique (CSAMT) for RQD estimation.
• Applied the method in a geologically diverse rock setting to depths over 1 km.
• Developed a 2D and 3D RQD estimation approach.

Main Results:

• The geophysical approach provides easier, faster, and cheaper access to geomechanical volumetric data.
• The study demonstrates the first use of CSAMT for RQD estimation at depths over 1 km in diverse rock.
• The method offers a more precise and thorough evaluation of rock integrity.

Conclusions:

• The proposed geophysical method enhances the accuracy and efficiency of RQD estimation for deep underground projects.
• This approach facilitates safer, steadier, and more affordable construction of deep underground structures.
• It leads to more objective geomechanical indices and reduces data inconsistencies in geotechnical modeling.