Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link


Centers for Disease Control and Prevention. CDC twenty four seven. Saving Lives, Protecting People
Search
            ×
                        Mining
                        Mining
                            NIOSH
                            All CDC
                    Submit
                For a full list of topics:A-Z Index
                Advanced Search
            Advanced Search


The National Institute for Occupational Safety and Health (NIOSH)


Section Navigation
			
			CDC Home





Mining Publication: Geomechanics of Reinforced Cemented Backfill in an Underhand Stope at the Lucky Friday Mine, Mullan, Idaho
Keywords: Idaho Installation Wood posts
Original creation date: July 2001
Authors: TJ Williams, DK Denton, MK Larson, RL Rains, JB Seymour, DR Tesarik
Report of Investigations - July 2001
Download PDF Document (5.39 MB)
NIOSHTIC2 Number: 20021603
Spokane, WA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2001-138, Report of Investigations 9655, 2001 Jul :1-18
Because backfill has occasionally collapsed into an active working area, posing a hazard to miners, engineers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health and Hecla Mining Company installed instruments in a cemented, backfilled, stope-ramp intersection at Hecla's Lucky Friday Mine, Mullan, Idaho. The purpose was to measure stress and strain changes in the backfill and reinforcing members during undercut mining. The instruments were monitored for 6 months while three successive cuts were mined below the intersection. Readings showed induced loads up to 3450 kPa (500psi) in the backfill as stope walls converged 2.5 to 12 cm (1 to 5 in.). The backfill then deformed against the top and bottom plates of the 2-m- (6-ft-) long vertical rock bolts installed as reinforcement, producing loads to 177 kN (40,000 lb) on the rock bolts. We hypothesize that a compressive zone was created in the backfill that allowed the backfill to remain stable as long as the compressive zones from adjacent rock bolts overlapped. This hypothesis is presented in graphical form. Of particular interest was the effect of loading on trusses installed to augment the vertical rock bolts and wire mesh typically installed in backfill. Data from the instruments indicate that wall closure perpendicular to the vein induced loads in truss legs parallel to the vein and in the rock bolt driven through the center of the truss, but, because they are designed to function under tension, truss legs perpendicular to the vein supplied insignificant support as a result of compressional forces from wall closure. Based on this study, use of trusses was discontinued, and an alternative support system of wood beams and posts was installed as needed to ensure the safety of miners working beneath the backfill in stope-ramp intersections.
Image of publication Geomechanics of Reinforced Cemented Backfill in an Underhand Stope at the Lucky Friday Mine, Mullan, IdahoReport of Investigations - July 2001
Download PDF Document (5.39 MB)
NIOSHTIC2 Number: 20021603
Spokane, WA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2001-138, Report of Investigations 9655, 2001 Jul :1-18
See Also
60 Years of Rockbursting in the Coeur D'Alene District of Northern Idaho, USA: Lessons Learned and Remaining Issues
In Situ Stress at the Lucky Friday Mine (In Four Parts): 2. Analysis of Overcore Measurement From 5300 Level
In Situ Stress at the Lucky Friday Mine (In Four Parts): 3. Reanalysis of Overcore Measurements from the Star Mine
In Situ Stress at the Lucky Friday Mine (In Four Parts): 4. Characterization of Mine In Situ Stress Field
Investigation of a Rock-Burst Site, Sunshine Mine, Kellogg, Idaho
Make it Safer with Roof Screen
A Medium Frequency Wireless Communication System for Underground Mines
Musculoskeletal Stress on Miners Performing Roof Screening Operations
New Tricks for an Old Elephant: Revising Concepts of Coeur d'Alene Geology
Technical Bulletin Pager Phones: Installation
Page last reviewed: July 14, 2015
Page last updated: July 14, 2015
Content source: National Institute for Occupational Safety and Health, Mining Program
Facebook
        Twitter
        LinkedIn
        Syndicate Mining
        Site BrowserSafety and Health TopicsData & StatisticsMethodologyMine DisastersMSHA Data FilesMine & Mineworker ChartsTools & PublicationsTools You Can UsePublicationsNews & ArticlesResearch ProgramNORA Mining CouncilStrategic PlanMining Program, 2019-2023Miner Health Program, 2020-2030ProjectsContractsFunding OpportunitiesMining LinksAbout UsContact NIOSH MiningEmploymentFacilitiesHistoryVisitor Information NIOSH Homepage
 NIOSH A-Z
Workplace Safety & Health Topics
Publications and Products
Programs


About CDC
					Contact Us
					800-232-4636
 Facebook Twitter Instagram LinkedIn Youtube Pinterest Snapchat
 CONTACT CDC
				Contact Us
							Call 800-232-4636
							Email Us
			ABOUT CDC
				About CDC
							Jobs
							Funding
			POLICIES
				Accessibility
							External Links
							Privacy
							Policies
							No Fear Act
							FOIA
							OIG
							Nondiscrimination
							Vulnerability Disclosure Policy
			CONNECT WITH US
				Facebook
								Twitter
								Instagram
								LinkedIn
							Youtube
								Pinterest
								Snapchat
								Email
			LANGUAGES
				Español
							繁體中文
							Tiếng Việt
							한국어
							Tagalog
							Русский
							العربية
							Kreyòl Ayisyen
							Français
							Polski
							Português
							Italiano
							Deutsch
							日本語
							فارسی
							English


U.S. Department of Health & Human Services
			Accessibility
			External Links
			Privacy
			Policies
			No Fear Act
			FOIA
			Nondiscrimination
			OIG
			Vulnerability Disclosure Policy
			USA.gov


Exit Notification / Disclaimer Policy Close
 Links with this icon  indicate that you are leaving the CDC website. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
				Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
				You will be subject to the destination website's privacy policy when you follow the link.
				CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. Website Disclaimers
 Cancel Continue