The Skaland mine is a graphite mine in Senja island, North of Norway. The mine is located in a granite rock (possibly be Migmatite). The owner of the mine – Leonard Nilsen and Sons (LNS) – plans for a new excavation profile, and the stability of the excavation needs to be checked for the planning. For the stability analyses, SINTEF is asked to carry out stress measurement, using 2D and 3D measuring methods. Results of the stress measurement are used as an important input for numerical models to analyse the stability of the mine. This paper is describing the whole process of the stress measurements and the numerical analyses for the mine.
Skaland mine is a graphite mine located in the Senja island, North of Norway. The excavation profile consists of a complex of service tunnels and several production tunnels at level 25 and level 45 m.a.s.l (above sea level). The location of the mine is presented in Figure 1. To evaluate the stability of the excavation for the mine, stress measurement had been carried out at the mine during June 2009. Results of the stress measurement are used as input data for the stability analyses. For the stability analyses, numerical modeling, Phase 2D (Rocscience 2005), is used.
With long development and strong experience in the field of stress measurement as presented in Table 1, SINTEF has been asked to carry out the task at Skaland mine in 2009. 2.1 Equipment and procedure for 2D stress measurements A diamond drill hole (76mm outer diameter) is drilled to the desired depth. A two dimensional measuring cell (door stopper) that contains a strain gauge rosette, is inserted into the hole with a special installing tool and glued to the bottom of the hole.