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The stress state of rock has a significant impact on the planning, safety and cost of mining and rock construction. Rock stresses are caused by factors such as crustal pressure, residual stresses from glacial periods and plate movements, and are monitored during construction or extraction to ensure safety. 

However, current methods for measuring the stress state of rock are often expensive and complex. A new method developed at Aalto University uses stress inversion, which allows fast and accurate monitoring of the stress state. 

'Our technology offers a completely new way to manage the risks associated with rock stress and ensure safety in quarrying and construction projects,' says Lauri Uotinen, researcher at Aalto University. 'Especially in mining conditions, collapse prediction and efficient extraction are crucial for both worker safety and costs.'

In addition to mines, the technology can be used in the design of tunnels and underground storage facilities, for example. The innovation, which recently received the Europe patent, uses measurements with instrumented rock bolts or extensometers and stress inversion, the same principle as in computed tomography, where measured signals are used to calculate an image of an invisible internal structure. Instrumented rock bolts are equipped with strain sensors that measure displacements in the rock mass. Using the measured displacements, a numerical algorithm calculates the stress changes, allowing real-time monitoring of the stress state. 

'Similar solutions have not been widely used before. Our method is cheaper and easier to install than previous ones, combining the traditional bolt strengthening function with monitoring,' says Uotinen. 

The method has been tested at Aalto University's underground laboratory and in collaboration with a Finnish mining company. The team is currently looking for companies to use the innovation, such as rock reinforcement product manufacturers or companies that provide measurements.

Aalto University applies for dozens of patents every year and the proprietary technology resulting from research at the university is used by many international companies. In addition to patented technology, Aalto University licenses and sells the necessary know-how to implement the technology.