Fastening in Rock Mass-Structural Design of Shallow Embedded Anchors in Inhomogeneous Substrate

Area of Science:

• Geotechnical Engineering
• Structural Engineering

Background:

• Lack of established design guidelines for rock as a base material for post-installed anchors.
• Variability in rock properties and installation parameters creates uncertainty in design resistances.

Purpose of the Study:

• Identify key parameters influencing rock base material properties for anchors.
• Develop assessment methods and design approaches for post-installed anchors in rock.

Main Methods:

• Evaluation of rock characteristics.
• In situ pull-out tests across diverse geologies (granite, limestone, mica schist, dolomite, granulite).
• Discrete element modeling to analyze load-bearing behavior.

Main Results:

• Rock discontinuities identified as the primary factor affecting load-bearing capacity.
• Proposed assessment methods and resistance partial safety factors (2.5, 2.0, 1.7) for varying uncertainty levels.
• Defined a rebound hammer limit value (R ≥ 36) for low uncertainty, noting limitations for schistose rock.

Conclusions:

• Established a design approach for determining design resistances of shallow fasteners in rock mass.
• Provides engineers with a more certain basis for anchor applications in rock.
• Highlights the critical role of understanding rock discontinuities in anchor design.