Laserfiche WebLink
1 <br />-4- <br />' The SRMR system was applied at both the Island Copper :Sine, <br />British Columbia, and the Getchell Mine in Nevada and the <br />results correlated with back analyses of failed slopes as <br />' described in Robertson, Olsen and Pierce, 1987, and Robeson <br />1988. Table 4 summarizes the results of the strength/rating <br />correlation found far the weak rock masses at these mines. <br />' BASIS FOR SRK GEOMECYANICS CLASSIFICATION OF ROC:C MASSES <br />The difference between t.'~e CSIR and SRK classification <br />systems can be seen in a comparison of Tables 2 and 3. <br />lil Rating for Groundwater <br />The amount of water present in the rock mass does not <br />influence the rock mass strength. It is a destabilizing force, <br />and should be accounted for as such in any stability analysis. <br />' The groundwater parameter is therefore dropped in SRK-RMR <br />system. To maintain the validity of the CSIR-RMR correlation <br />for stronger rock masses, the maximum rating value for tY.~e <br />' parameter (15) has been added to parameter 1 (strength of" intact <br />rock). This results in the rating assignment of the higr.,est <br />intact rack strength class increasing from 15 to 30. <br />' (ii1 Rating for Intact Rock Strength <br />apart from the increased rating value resulting from the <br />' groundwater modification trie rating for this parameter is <br />unchanged for rock of hardness R1 (refer Table 1) or greater. <br />Additional classes and ratings have been added for materials in <br />the soil strength range SS to S1. This allows the effects of <br />' very weak, soil like, materials to be included in the roc!c sass <br />rating. <br />(iii)Ratina for ROD <br />The conventional RQD is replaced by a new parameter; the <br />1 Handled RQD (HRQD). The HRQD is measured in the same way as the <br />RQD after the core has been firmly handled and "worried" .in an <br />attempt to break the core into smaller fragments. During <br />"handling" the core is firmly twisted and bent but without <br />substantial force or use of any tools or instruments. R1 rock <br />core, without planes of weaknesses, will not break under such <br />handling. <br />' The adoption of HRQD allows account to be taken of weakly <br />cemented joints. It also prevents the assignment of large <br />' rating values for continuous core in soft soil like materials, <br />clays for example. <br /> <br /> <br />1 <br />