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Monitoring System of rock stability in mines based on Advanced 4D seismic analysis.

Periodic Reporting for period 1 - Mines-In-Time (Monitoring System of rock stability in mines based on Advanced 4D seismic analysis.)

Reporting period: 2019-10-01 to 2020-03-31

Catastrophic ground collapse in mines is the main hazard for safety of workers and for the mining activity. Indeed, some mining methods, such as longwall and room and pillar retreat, create overburden to cave. This creates highly variable stress conditions that can be difficult to predict. From both the safety and production point of view, unplanned ground falls resulting from these conditions are unacceptable but still frequent, causing fatalities, stoppage in operations, damage of equipment and lost ore reserves. Monitoring the alteration of the state of the rock mass during underground mining operations plays a key-role to forecast the failure of the rocks. This is currently done through 3D LET (Local Earthquake Tomography) computational analysis on data provided by existing seismographic networks once every month and through quasimanual analysis of experts: the procedure is time-consuming and expensive, the results are difficult to be interpreted by the mine’s decision makers and not fully reliable (high possibility of error). Mines-In-Time (MIT) is a solution developed by Space Earth Technologies (SET) for monitoring in almost real time the rock mass stress alteration during mining operations, to be integrated in a Decision Support System (DSS) to avoid risks and cost related to mines collapse. The system is based on the innovative 4D LET algorithm (three spatial dimensions + time), able to analyse both natural and induced micro-seismicity such as movements due to drilling or other mining operations. The feasibility study allowed to analyse the needs, specifications and potentials for market acceptance of MIT solution. The outcomes of the Feasibility Study have demonstrated the potentialities of the MIT solution.
The work carried out in the feasibility study consisted in: 1) Definition of the workflow of the MIT software code the specs for MVP and its preliminary design: a four-dimensional (4D) numerical model of the rock elasticity for a target volume of the mine. Numerical model is defined through the collection several millions of elastic models that are able to reproduce the observed data. The pool of elastic models collected is analysed in the final step to elaborate an average four- dimensional numerical model. The collection of elastic models can be post- processed for extracting useful information for mining company (i.e. correlation between seismicity and elastic properties. 2) Definition of the development plan to reach the Minimum Viable Product on two complementary lines: to increase its efficiency, in terms of CPU-hours per elastic model, to extend its portability toward different mining markets. 3) Definition of the two different typologies of services for assisting mining company during production: a full monitoring system, with daily reports, a tool for planning next stages of production, with weekly or monthly reports. 4) Analysis of the Microseismic Monitoring Technology (MMT) market that is expected to reach € 900 million in 2026. 5) Identification of the number of potential applications, in which Rockburst-prone longwall faces coal mines constitute the largest share. 6) Customer validation with experts in the field, who were interviewed to validate the product marketability. 7) The Business Model strategy was defined based on a three-level offer: base, advanced and premium services. The costs and prices of the different products were defined. 8) The Go-to-market strategy and Profit and Loss were defined, including quantification of the investment required for product development and demonstration.
MIT is based on a 4 dimensions Local Earthquake Tomography (4D LET) methodology and is able to analyze both natural and induced micro-seismicity due to mining operations. This technique is a unparalleled upgrade of the traditional ambient noise analysis and time lapse 3D LET, since the addition of the 4th dimension (time) allows a real time monitoring of ground deformation related to the stress variation and provides an instant alert in case of risky conditions, using data provided by the existing networks of seismographs already installed in most of the mining sites (no extra hardware to be installed). In addition, the approach allows the system to define automatically the optimal resolution parameters in space and time, requiring minimum intervention from the operator. Hence, the results are highly repeatable and provide time-dependent high-resolution analysis of mine conduits, monitoring the true alteration of a rock mass. The use of MIT will grant outstanding advantages for end users: 1) Reduction of health and safety risks of personnel involved in underground works and reduction of economic losses due to collapses and failures - in case of accident the operations can be stopped for weeks or months before recovering complete production, with losses of millions €. 2) Improvement of planning and scheduling of mining and maintenance operations, saving costs of inspections, analysis and monitoring, estimated in the order of 30% with respect to the current practices.
4D LET analysis