Mining Topic: Horizontal Stress

What is the health and safety problem?

High horizontal stresses produce extensive and sudden rock failures. The U.S., Australian, and United Kingdom coal and the Canadian hard rock industries have long recognized the significance of high horizontal stresses as a factor affecting the stability of roof and rib conditions in underground mines.

What is the extent of the problem?

High horizontal stress is most prevalent in the Eastern and Midwestern coal beds but does occur in other locations.

How is the NIOSH Mining program addressing this problem?

 The Office of Mine Safety and Health Research (OMSHR) has been conducting research to develop a better fundamental understanding of ground control strategies through field and laboratory studies. The consequences of widening rooms, changing geology and horizontal stress, and different roof support systems have been addressed. Such specialized techniques as the "advance and relieve" plan have been studied. In this plan, horizontal stresses are relieved by removing a pillar on one side of a panel as the panel advances, creating a cave that relieves horizontal stress across the panel.

What are the significant findings?

OMSHR has developed best practices for mines encountering high horizontal stress. A software program, Analysis of Horizontal Stress Effects in Mining (AHSM), was developed to give mine designers the optimal orientation for entries.

What are the next steps?

OMSHR is monitoring the industry to determine if there is an upswing in potentially related hazards.