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Mining Project: Development of Guidelines for the Design of Support Systems to Manage Coal Mine Rib Hazards

Project DetailValue
Principal Investigators
  • Tristan Jones, NIOSH, 412-386-6536
Start Date10/1/2011
Purpose

The primary objective of the project is to develop guidelines for determining the appropriate level of support and design methods for support systems to minimize the risk and severity of injuries to miners from rib falls in underground coal mines.

Program Area
Keywordsground control, mining, underground mining

Research Summary

The primary objective of this project is to develop guidelines for determining the appropriate level of support and design methods for support systems to minimize the risk and severity of injuries to miners from rib falls in underground coal mines. A secondary objective is to identify the most effective support practices and techniques currently used to manage the coal rib hazard and to communicate this information to the industry. Two types of support systems have to be considered in this project, and the research will develop guidelines for both types of support systems:

  • One based on intrinsic support or rib bolts
  • One based on prop-type supports

The development of a design methodology and guidelines for coal mine rib support systems will be based primarily on an empirical approach, which will involve the creation and analysis of a database that contains case histories of rib support. To establish such a database, information on the seam, mine, and site conditions and support parameters as well as an evaluation of the performance of the rib support systems will be obtained during mine and underground site visits. Design models will then be developed and the most influential parameters determined from a multivariate statistical analysis of the database. To succeed in the development of a rib support design methodology and to allow for valid models to be defined, this approach requires a sufficiently large database covering a range of conditions.

The numerical modeling analyses that will be done for both the rib-bolt based and prop-type support systems will provide a much needed insight into the mechanisms of rib collapse and the way in which rib supports interact with the potentially unstable fragments of rock or coal. This understanding is expected to allow the critical aspects of the rib hazard to be identified and targeted support systems to be developed. Based on the statistical models, the instrumented test sites, the numerical modeling and field trials, a rib support design methodology and guidelines will be developed for both types of support.

The specific aims of the project are to: 

(1) Empirically determine the critical design parameters and criteria for rib-bolt based support systems for controlling coal mine ribs.

(2) Evaluate the interaction of coal rib and rib-bolt based support systems at specific sites to assist in the development of design standards through instrumented field sites and numerical modeling.

(3) Empirically determine the critical design parameters and design criteria for prop-type support systems for controlling coal mine ribs.

(4) Evaluate prop-type supports in the laboratory, in field trials, and through numerical modeling to determine their effectiveness and design characteristics in supporting the coal rib, then develop design standards for these systems.

(5) Develop a software package to be used to implement the rib support guidelines and design methodology. Describe the project's major activities, including a timeframe for completing each one. 

The following tasks will be conducted for the project:

Task 1. Data Collection and Development of Rib Support Database (FY 2012 1st Qrt to 2013 4th Qrt). The goal of the data collection is to quantify the parameters that could affect rib stability and therefore affect the design and performance of a rib support system. The outcome of the rib support is a key component that will be assessed both quantitatively and qualitatively.

Task 2. Statistical Analysis of Database (FY 2012 4th Qrt to 2014 4th Qrt.) A statistical analysis of the data will be conducted when there is sufficient data and upon completion of the database. Because of the binary nature of the outcomes, satisfactory or unsatisfactory, and the expected categorical nature of some of the independent variables, a logistic regression analysis will be utilized to evaluate the data. The goal of this analysis is to build a statistical model that can be used to form the basis for a rib support design methodology and guidelines. The models will be used to establish the level of support that will have a high likelihood of being successful for the conditions and identify the parameters that have the most influence on the support design and performance.

 Task 3. Monitoring and Analysis of Rib-Bolt Support Performance (FY 2012 2nd Qrt to 2014 4th Qrt). A better understanding will be developed of the interaction between a rib-bolt based support system and the fractured coal rib so that appropriate support systems can be designed or the designs improved. There are two parts to this task, the monitoring of rib and support performance by instrumented field sites and numerical modeling calibrated from the instrumented case studies and observations.

 Task 4. Evaluation of Prop-Type Rib Supports (FY 2012 2nd Qrt to 2014 4th Qrt). The performance of the prop-type support will be evaluated and used to supplement the data collected on prop-type support under Task 1. The effectiveness of the prop support in controlling the coal rib will be further investigated, and the conversion of the prop-type support to an equivalent level of rib-bolt support will be developed. This will be accomplished though both the field trials and numerical modeling. Laboratory tests will be used to evaluate and delineate the important support characteristics for a prop-type support in providing rib control.

Task 5. Development of Rib Support Design Methodology and Software Package and Identification of "Best Practices" (FY 2014 2nd Qrt to 2015 4th Qrt). A design methodology and guidelines will be developed for rib support that can be used for either rib-bolt or prop-type support systems. The basis for the design methodology is the statistical models developed in Task 2 from the databases. The support requirements will be given in terms of the most significant parameters identified through the statistical analysis. The guidelines will be put into a design software package that can be used by mine engineers to develop an appropriate rib support design for the conditions at a mine or site or by regulators to evaluate support system designs. How the guidelines should be applied and the assumptions and limitations for the guidelines will be reported. Numerical modeling will examine the interaction between the fractured coal ribs and the support system to better understand why certain support systems may be more effective or successful in controlling the coal rib.


 

 

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