SAQA All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.
SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD: 

Demonstrate an understanding of the role of pillars as a support medium, design considerations and principles 
SAQA US ID UNIT STANDARD TITLE
256853  Demonstrate an understanding of the role of pillars as a support medium, design considerations and principles 
ORIGINATOR
SGB Mining and Minerals 
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-  
FIELD SUBFIELD
Field 06 - Manufacturing, Engineering and Technology Fabrication and Extraction 
ABET BAND UNIT STANDARD TYPE PRE-2009 NQF LEVEL NQF LEVEL CREDITS
Undefined  Regular  Level 4  NQF Level 04 
REGISTRATION STATUS REGISTRATION START DATE REGISTRATION END DATE SAQA DECISION NUMBER
Reregistered  2018-07-01  2023-06-30  SAQA 06120/18 
LAST DATE FOR ENROLMENT LAST DATE FOR ACHIEVEMENT
2024-06-30   2027-06-30  

In all of the tables in this document, both the pre-2009 NQF Level and the NQF Level is shown. In the text (purpose statements, qualification rules, etc), any references to NQF Levels are to the pre-2009 levels unless specifically stated otherwise.  

This unit standard does not replace any other unit standard and is not replaced by any other unit standard. 

PURPOSE OF THE UNIT STANDARD 
This unit standard will be useful for persons who are pursuing a career in Rock Engineering.

This unit standard is intended to promote general skills, knowledge and understanding of the role of pillars as a support medium, design considerations and principles in the mining and minerals sector in order to ensure knowledgeable and informed workers.

People credited with this unit standard are able to:
  • Demonstrate an understanding of the different classes of support pillars in mining.
  • Demonstrate an understanding of the functions of support pillars in mining.
  • Demonstrate an understanding of the principles of design for support pillars.
  • Demonstrate an understanding of the factors that need to be considered when applying prescribed design principles for support pillars. 

  • LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
    It is assumed that learners are already competent in:
  • Communication and Mathematical literacy at NQF Level 3. 

  • UNIT STANDARD RANGE 
    N/A 

    Specific Outcomes and Assessment Criteria: 

    SPECIFIC OUTCOME 1 
    Demonstrate an understanding of the different classes of support pillars in mining. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The different classes of pillars are described in terms of their width to height ratios in the context of mining operations. 
    ASSESSMENT CRITERION RANGE 
    Description must include:
  • Crush pillars.
  • Yield pillars.
  • Non-yield pillars.
  • Squat.
     

  • ASSESSMENT CRITERION 2 
    The effect of the width to height ratios for the different classes of pillar on the stress strain behaviour are explained and related to the increased strength of laboratory rock specimens with increased confinement in the context of mining operations. 

    ASSESSMENT CRITERION 3 
    The role of the different classes of support pillars is described with respect to their regional and/or local functions in the context of mining operations. 
    ASSESSMENT CRITERION RANGE 
    Description must include:
  • Crush pillars.
  • Yield pillars.
  • Non-yield pillars.
  • Squat.
     

  • SPECIFIC OUTCOME 2 
    Demonstrate an understanding of the functions of support pillars in mining. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The different types of support pillars and their functions are described in the context of mining operations. 
    ASSESSMENT CRITERION RANGE 
    Description must include:
  • Crush pillars.
  • Rigid instope pillars.
  • Bracket pillars.
  • Boundary/barrier pillars.
  • Satellite pillars.
  • Stabilising pillars.
  • Rib pillars.
  • Crown pillars.
  • Buttress pillars.
  • Water barrier pillars.
  • Shaft pillars.
     

  • ASSESSMENT CRITERION 2 
    The requirements of support pillars is explained for different depth environments in the context of mining operations. 
    ASSESSMENT CRITERION RANGE 
    Explanation must include:
  • Shallow.
  • Intermediate.
  • Deep.
  • Ultra deep.
     

  • ASSESSMENT CRITERION 3 
    The stress strain characteristics of support pillars are explained using simple annotated sketches in the context of mining operations. 
    ASSESSMENT CRITERION RANGE 
    Explanation must include:
  • Departure from elasticity.
  • Points of brittle fracture.
  • Peak strength.
  • Post peak stiffness.
  • Strain hardening.
  • Strain softening.
  • Residual strength.
     

  • SPECIFIC OUTCOME 3 
    Demonstrate an understanding of the principles of design for support pillars. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The tributary area method of calculating pillar stress in shallow mines is described, and the manner in which this can be used to determine the factor of safety is demonstrated in the context of mining operations. 

    ASSESSMENT CRITERION 2 
    The empirical pillar strength formulae available are described and their limitations of use explained in the context of mining operations. 
    ASSESSMENT CRITERION RANGE 
    Description/Explanation must include:
  • Salamon and Munro power law.
  • Madden's squat pillar formula.
  • Galvin et al power law.
  • Obert and Duvall hard rock power law.
  • York linear.
  • Van der Merwe power law and linear.
     

  • ASSESSMENT CRITERION 3 
    Dimensions of pillars applicable to design criteria are obtained from underground observations and/or working plans using accepted methods in the context of mining operations. 

    ASSESSMENT CRITERION 4 
    The use of width to height ratio as a design criterion is explained in the context of mining operations. 

    ASSESSMENT CRITERION 5 
    The Chamber of Mines shallow mining guidelines for pillar design are explained in the context of mining operations. 

    ASSESSMENT CRITERION 6 
    The concepts of energy release rate (ERR) and average pillar stress (APS) as design criteria for stability pillars are described with respect to operating depth, mining spans and pillar size. 

    ASSESSMENT CRITERION 7 
    The rationale behind the use of bracket pillars to reduce the potential for slip or bursting on geological features is explained in the context of mining operations. 

    ASSESSMENT CRITERION 8 
    The concept of excess shear stress (ESS) and the manner in which it is used as a design criterion for bracket pillars is described in the context of mining operations. 

    SPECIFIC OUTCOME 4 
    Demonstrate an understanding of the factors that need to be considered when applying prescribed design principles for support pillars. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The effect of pillar shape when using tributary area theory to design support pillars is described, and the method of correcting for non-square pillars is provided in the context of mining operations. 

    ASSESSMENT CRITERION 2 
    The limitations of the empirical pillar design formulae are described in the context of mining operations. 

    ASSESSMENT CRITERION 3 
    The effect of the variability of rock strength, pillar sizes and stoping widths on the calculated factor of safety is described with respect to potential for pillar failure. 

    ASSESSMENT CRITERION 4 
    The effect of the blast damage zone on pillar stability is explained in terms of legal and operational requirements. 

    ASSESSMENT CRITERION 5 
    The concept of effective width to height ratio is described and related to the design of stabilizing pillars in terms of legal and operational requirements. 

    ASSESSMENT CRITERION 6 
    The risks involved with under-designed bracket pillars are explained in terms of legal and operational requirements. 

    ASSESSMENT CRITERION 7 
    The influence of pillars in close proximity to each other is explained in terms of legal and operational requirements. 

    ASSESSMENT CRITERION 8 
    The mode of failure of support pillars are described in terms of legal and operational requirements. 
    ASSESSMENT CRITERION RANGE 
    Description must include:
  • Indentation (punching).
  • Poisson's effect.
  • Shear of weak layers or planes.
  • Bursting.
     

  • ASSESSMENT CRITERION 9 
    Foundation failure due to pillar punching or shearing along the edge of the stability pillars is explained in terms of legal and operational requirements. 


    UNIT STANDARD ACCREDITATION AND MODERATION OPTIONS 
  • Anyone assessing a learner or moderating the assessment of a learner against this unit standard must be registered as an assessor with the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA.
  • Any institution offering learning that will enable the achievement of this unit standard must be accredited as a provider with the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA.
  • Assessment and moderation of assessment will be overseen by the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA, according to the ETQA's policies and guidelines for assessment and moderation.
  • Moderation must include both internal and external moderation of assessments, unless ETQA policies specify otherwise.
  • Anyone wishing to be assessed against this unit standard may apply to be assessed by any assessment agency, assessor or provider institution that is accredited by the relevant ETQA. 

  • UNIT STANDARD ESSENTIAL EMBEDDED KNOWLEDGE 
    The following essential embedded knowledge is addressed in an integrated way in the unit standard:

    Knowledge that the assessor will evaluate:
  • Different classes of support pillars.
  • Functions of support pillars in mining.
  • Principles of design for support pillars.
  • The factors that need to be considered when applying prescribed design principles for support pillars.

    Causes and effects (Occupational Health and Safety):
  • Use of equipment.
  • Use of personal protective equipment.
  • Adherence to occupational health and safety requirements.
  • Work related hazards and associated risks.

    Regulations, legislation, agreements, policies and standards:
  • Safety, health and environmental legislation and regulations.
  • Quality policies, standards and agreements. 

  • UNIT STANDARD DEVELOPMENTAL OUTCOME 
    N/A 

    UNIT STANDARD LINKAGES 
    N/A 


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Identify and solve problems and make decisions using critical and creative thinking.

    Note:
  • The ability to explain how a range of factors determines the behaviour of pillars and the various criteria to be employed when designing pillars. 

  • UNIT STANDARD CCFO COLLECTING 
    Collect, analyse, organise and critically evaluate information.

    Note:
  • The ability of the learner to assess and apply various techniques relating to pillar design. 

  • UNIT STANDARD CCFO COMMUNICATING 
    Communicate effectively, using visual, mathematical and/or language skills in the modes of oral and/or written presentations.

    Note:
  • The use of neat, simple and concise sketches and equations to demonstrate understanding. 

  • UNIT STANDARD CCFO SCIENCE 
    Use science and technology effectively and critically showing responsibility towards the environment and health of others.

    Note:
  • The use of appropriate design criteria to design pillars specific to the particular mining environment to reduce the rockfall and rockburst risk. 

  • UNIT STANDARD CCFO DEMONSTRATING 
    Demonstrate an understanding of the world as a set of related systems by recognising that problem-solving contexts do not exist in isolation.

    Note:
  • The knowledge and understanding that a variety of factors affect the behaviour of pillars and that these related factors must be taken into account when designing pillars. 

  • UNIT STANDARD ASSESSOR CRITERIA 
    N/A 

    REREGISTRATION HISTORY 
    As per the SAQA Board decision/s at that time, this unit standard was Reregistered in 2012; 2015. 

    UNIT STANDARD NOTES 
    Terminology:

    Specified Requirements:

    Specified requirements include legal and site-specific requirements and are contained in one or more of the following documents:

    Legal:
  • Relevant Acts: e.g. Mine Health and Safety Act and Regulations, 1996 (Act 29/1996), and Minerals Act and Regulations, 1991 (Act 50/1991).
  • Mandatory Codes of Practice.
  • SANS and other relevant Standards.
  • Chief Inspector of Mines' Directives/Instructions.
  • Guidelines issued by the Chief Inspector of Mines.

    Site-Specific:
  • Hazard Identification and Risk Assessments (HIRA).
  • Occupational Health and Safety Risk Management Programme.
  • Managerial Instructions.
  • Mine Standard Procedures.
  • List of Recorded OH and S Risks.
  • Working Guides.
  • Equipment and Materials Specifications. 

  • QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Elective  62796   Further Education and Training Certificate: Strata Control Operations  Level 4  NQF Level 04  Reregistered  2023-06-30  MQA 


    PROVIDERS CURRENTLY ACCREDITED TO OFFER THIS UNIT STANDARD: 
    This information shows the current accreditations (i.e. those not past their accreditation end dates), and is the most complete record available to SAQA as of today. Some Primary or Delegated Quality Assurance Functionaries have a lag in their recording systems for provider accreditation, in turn leading to a lag in notifying SAQA of all the providers that they have accredited to offer qualifications and unit standards, as well as any extensions to accreditation end dates. The relevant Primary or Delegated Quality Assurance Functionary should be notified if a record appears to be missing from here.
     
    NONE 



    All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.