Grout Pumping and Injection Operations TR 003 ▪ When stop pressure (refusal) is achieved and grout flow reduced to the minimum required, the packer valve shall be closed, and then the pump stopped. ▪ Release the pressure in the grout line by opening the grout recirculation valve and give the all-clear to release the grout hose from the packer. ▪ A Quality Assurance (QA) test shall be performed for each new mix (i.e. each different water/binder ratio) and the results recorded if required under the instruction. ▪ Packers shall remain in completed holes until the grout has reached initial set and able to resist the back-pressure in the hole. ▪ Once packers are removed (if they are able to be removed) from a hole, they must be thoroughly washed and flushed with water until clean. 3.3. Injection Criteria for Ground Conditions Whilst the overall procedures and techniques for pressure grouting remain the same and should be followed, certain injection criteria will vary depending on a range of factors here at EHM: ▪ Specific Ground Conditions. ▪ At what depth of the mine where grouting is to occur. ▪ The nature of the grouting round i.e. grouting of diamond drill holes, bulk fill, development grouting and vertical shaft grouting. Injection criteria will normally be provided by the Services Engineer and/or Shift Supervisor. In many instances and in order to obtain an effective grouted zone, grouting personnel are able to be flexible and make independent decisions. This is due to the unique and changing ground conditions here at EHM; however the core principles of pressure grouting must be adhered to, these are: ▪ Unless otherwise instructed, grout batches must be changed to a lower water binder ratio after a pre-determined amount of grout has been delivered. This is to prevent wastage of product, resources and in some cases negate previous grouting efforts. ▪ Individual drill holes can only be declared refused when the pre-determined stop criterion has been reached. ▪ All due care should be taken to ensure individual batches are accurate, including on occasion, specific additives and bonding agents i.e. fine sands, sawdust etc. For all ground conditions the starting grout mix will be a Water/Binder ratio of 2.0 and the pump (grout flow) rate will be between 15 – 30 litre/min. Below are two common injection criteria for typical ground conditions and open structured ground conditions here at EHM: Under no circumstances shall any person attempt to disconnect the grout hose from a packer (water control device) until the pump operator informs them that the pressure in the line has been released. If you are required to retreat to the tag board for firing while injecting grout into a hole either; ▪ Turn off discharge valve, flush the pump & agitator with water so that it is clean or ▪ Turn off discharge valve and open recirculation valve with pump stroking slowly while unattended.
RkJQdWJsaXNoZXIy MjE2NDg3