Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Mining Engineering

Committee Chair

Brijes Mishra

Committee Co-Chair

Yi Luo

Committee Member

Vladislav Kecojevic


Underground mines often experience roof falls in entries, crosscuts, and intersections of active mining sections, main travel ways, and belt entries. Roof fall heights greater than 20 ft (6 m) make re-bolting of the newly exposed roof dangerous and impractical. To protect mine personnel, belts, moving vehicles, and other equipment, mine operators typically install steel structures such as square or arch sets in the roof fall areas. Wood lagging is usually installed between the steel-sets to enclose the area and protect the entry from recurring falls. Usually the void space above the steel-sets and wood lagging is backfilled. However, backfilling high roof fall voids is costly, which causes some operators to leave the voids open. In this case, the durability of wood over time and the capability of the steel-set and wood lagging to resist falling rocks are unknown.

During the last few years, an impact-resistant (IR) lagging system was designed, tested, and developed to protect the steel-sets. Various IR steel-sets were approved by Mine Safety and Health Administration (MSHA) and installed in different underground roof fall rehabilitation projects. As of May 2020 more than 200 roof falls in 50 different coal mines were successfully rehabilitated by installing the IR steel sets in the US.

This study focuses on (1) design, development, and laboratory testing of the IR lagging panel, (2) steel-set design methodology according to the American Institute of Steel Construction (AISC) specifications, (3) capacity evaluation of the IR steel set using elasto-plastic structural analysis approach (4) two case studies of the performance of IR arch sets installed at various roof fall rehabilitation sites, and (5) an applicability evaluation guideline of the IR steel set for a given roof fall conditions.