Professor Piotr MAŁKOWSKI – AGH UST, Krakow, Poland

malkgeom@agh.edu.pl

TOPIC: Rock mass characterization and methods of underground roadways stability assessment – 16 teaching hours

Lectures (total 12-13h)

1. Core log tests and ISRM classification (2h)

Rock mass quality, drill-core investigations, drilling and coring bits, core barrels, core recovery, core logs storage, tests on core logs, important information, RQD, core logs selection for the laboratory tests, UCS and PLT, discontinuity spacing, condition of discontinuities, joint roughness, The basic rock mass characterization (ISRM 1981 and EN-ISO 14689:2017), the most common errors in classifying rock masses, factors influencing on underground working stability.

2. Rock mass classifications (4-5h)

Part 1

Definitions, The failure of rock mass next to the roadway, hard rocks and soft rocks, rock mass classifications through the years (Terzhagi, Deere, Wickham, Barton, Bieniawski, Hoek), RQD for roofs of underground workings in hard coal mines in Poland, recommendations for support design (Q system, RMR system), classifications for flysch rock mass, factors influencing on rock mass quality, relationship between RMR and Q, Empirical methods of rock mass properties assessment, Rock mass quality and load on the support and rockbolt length, “Ten Commandments” for using RMR and Q systems,

Part 2

Rock mass classification systems and their extensions in the world (MBR, MRMR, CMRS, CMMR), geotechnical classifications in mining practice, Rock mass classifications in Poland (for KGHM copper mines, for lead and zinc mines - recommendations for the support design), ERMF system and its evaluation in the field, ERMF recommendations for the support design.

3. Roadways monitoring systems (2h)

Rock mass and support monitoring. Roof beds separation and tell-tales. Load on standing support. Load on bolts. Rock mass stress control. Rock fracturing control. Manual and automatic systems.

4. How can you approach to the stability of underground mining workings (3h)

Procedures of underground objects designing. The engineering approach to the problem of underground workings stability. Roof Fall Risk Index. Using Artificial Neural Networks in geomechanical problems. Using Analytic Hierarchy Process in geomechanical problems. Roadway Design Efficiency index. Key factors of rock instability.

Laboratory exercises (total 3-4 hours)

Core log analysis and Rock mass quality evaluation (3-4h)

Information purchasing from the core log study. RMR rock mass quality analysis using 6-meter long core logs. Joint conditions – weathering, roughness and asperity. Immediate roof and main roof assessment. Rock bed assessment. Using of rock mass classifications in practice.

Recommended texts

1. Bieniawski, Z.T. 1989. Engineering rock mass classifications. New York: Wiley.

2. Bieniawski, Z.T. : RMR and Q - Setting records. Tunnels & Tunnelling International February 2008, pp. 26-29.

3. Hoek, E. : Practical Rock Engineering. Hoek’s Corner, rocscience.com – on-line.

4. Hoek, E., Kaiser, P.K., Bawden, W.F. : Support of Underground Excavations in Hard Rock. Balkema, Rotterdam 1995.

5. Małkowski, P., Juszyński, D. : Roof fall hazard assessment with the use of artificial neural network. International Journal of Rock Mechanics and Mining Sciences, 2021, 143, 104701.

6. Małkowski, P., Niedbalski, Z., Bednarek, Ł. : Automatic Monitoring System Designed for Controlling the Stability of Underground Excavation. Inzynieria Mineralna, 2021, 1(2), pp. 15–29.

7. Małkowski, P., Niedbalski, Z., Majcherczyk, T., Bednarek, Ł. : Underground monitoring as the best way of roadways support design validation in a long time period. Mining of Mineral Deposits, 2020, 14(3), pp. 1–14.

Grading policy

1. The participation in quiz.

2. The group discussion and activity.