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PhD projekt-Study on scale effect on rock mechanical parameters for rock joints

The project covers quality assured testing of rock joints on a uniquely large scale using a new shear test equipment. The test results constitute a link in the application of models for shear strength prediction of full-scale rock joints. The results will among others be used in the safety assessment of repositories for nuclear waste.

Aim and goal

The need for understanding the risk for sliding in the joints in the basement rock is of importance in the design of deeply located underground spaces. The project aims to contribute with high quality data from tests in a uniquely large scale for the development of models for full scale rock joints.


Replicas are castings from rock joints and forms an important part in the research work by that the use of replica allows for repeated tests with the same crack surface. However, the results can be difficult to interpret and occasionally contradictory.

Numerical models are used on basis of laboratory tests to predict the behaviour of full scale rock joints. Tests on different scales yields different results and a challenge is therefore to understand how a scale effect shall be considered in the development of models for full scale rock joints.


To derive a methodology for the generation of high quality data in the usage of replica and by this create conditions for consistent results. This is done by identification and quantification of critical steps in the manufacturing process of replica.

By the development and usage of a shear test equipment for uniquely large specimens the aim is to derive data that previously has not been accessible for increased understanding of the behaviour of full scale rock joints.


The data from this project can be used for research for a long time forward. The results will particularly be used in the safety assessment of repositories for nuclear waste in Sweden and Canada.


Project name

POST2 PhD project



RISE role in project

Ph.D. work

Project start



Total budget

8 Msek


Swedish Nuclear Fuel and Waste Management Co, Royal Institute Of Technology


BeFo (Stiftelsen Bergteknisk Forskning)

External press

Supports the UN sustainability goals

7. Affordable and clean energy
11. Sustainable cities and communities
Jörgen Larsson

Contact person

Jörgen Larsson


+46 10 516 56 94

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