Ground support is an essential component of the mining process in the Kiirunavaara underground iron ore mine. An efficient and effective system of ground support increases the safety of the work environment, prevents disruption of production and minimizes dilution of ore.
A combination of rock bolts and surface supports is used to achieve the goal of reinforcing, holding and retaining the rock mass in a mining excavation. The support system used in Kiruna includes stiff and yielding rock bolts, cable bolts, shotcrete and welded wire mesh among others. It is essential to evaluate the capacity of each component in the ground support system for the purposes of design and quality control. The capacity of the elements can be defined based on their energy absorption capacity, load bearing capacity, deformation capacity and toughness among other parameters.
LKAB has built a test rig for testing the capacity of surface reinforcements with drop testing. The facility is located at the Kiruna underground mine at level 768. With the facility one will be able to perform standardized tests (like ASTM C1550) or perform other tests that may eventually lead to a better understanding of the ground support system.
Figure 1: overview of the drop test facility
The aim of the project is to evaluate the load absorption capacity of surface support used in the Kiruna underground mine. The student will perform drop tests on shotcrete panels and welded wire mesh. The tests will be performed on test specimens of varying dimensions with varying drop heights and weights. The installed system in the test facility can measure deformations and impact loads. Thus, the limit capacity values of the support elements should be stated in terms of energy absorption, load and deformation.
The major activities in the project include, but are not limited to:
- Literature review: the student will assess the available literature on the practice of capacity testing for surface support elements and systems
- Field testing: the student performs drop testing on specimens of various sizes with various loading.
- Analysis: data obtained from the testing facility will be analyzed. It is recommended the student to have some command of mathematical tools such as MATLAB, Python or other similar programs to be able to analyze the data
- Written report (thesis): the student shall compile the works performed into a final report
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