1 - GEOTECHNICAL INVESTIGATION REPORT - 150320 LAR Road Investigation Ridgewood Geotech 23042015_Rev1-Combined

                                 GEOTECHNICAL TERMS AND SYMBOLS (cont’d)
Rock Description
Rock is generally described in the field using visual and tactile methods. The following provides
details of the descriptions shown on the geological logs.
ROCK STRENGTH CLASSIFICATION
                                     Point Load
 Symbol             Term           Strength Index                                              Field Guide
                                     Is(50) (MPa)
    EL          Extremely Low              ≤ 0.03         Easily remoulded by hand to a material with soil properties
                                                          Material crumbles under firm blows with sharp end of pick; can be peeled with
   VL             Very Low            > 0.03 to 0.1       knife; too hard to cut a triaxial sample by hand. Pieces up to 30 mm can be broken
                                                          by finger pressure.
                                                          Easily scored with a knife; indentations 1 mm to 3 mm show in the specimen with
                                                          firm blows of pick point; has dull sound under hammer. A piece of core 150 mm
    L                Low              > 0.1 to 0.3
                                                          long by 50 mm diameter may be broken by hand. Sharp edges of core may be
                                                          friable and break during handling.
                                                          Readily scored with a knife; a piece of core 150 mm long by 50 mm diameter can
    M              Medium              > 0.3 to 1
                                                          be broken by hand with difficulty.
                                                          A piece of core 150 mm long by 50 mm diameter cannot be broken by hand but
    H               High                > 1 to 3          can be broken with pick with a single firm blow; rock rings under hammer.
                                                          Hand specimen breaks with pick after more than one blow; rock rings under
   VH             Very High            > 3 to 10
                                                          hammer.
                                                          Specimen requires many blows with geological pick to break through intact
   EH           Extremely High             > 10
                                                          material; rock rings under hammer.
Notes:
1. These terms refer to the strength of the rock material and not to the strength of the rock mass which may be
   considerably weaker due to the effect of rock defects.
2. Anisotropy of rock material samples may affect the field assessment of strength.
3. Rock strength is determined based on the point load strength index test Is(50). The field guide is used when no tests are
   available.
4. The point load strength index Is(50) test is described in Australian Standard AS 4133.4.1. The relationship between
  Is(50) and UCS (unconfined compressive strength) will vary with rock type and strength, and should be
  determined on a site specific basis. UCS values are often in the range 10 to 30 x Is(50).
5. Refer to “Symbols” to see how the point load strength index Is(50) test results are presented on the geological logs.

ROCK MATERIAL WEATHERING CLASSIFICATION
   Symbol                     Term                                                            Field Guide
                                                      Soil developed on extremely weathered rock; the mass structure and substance fabric are
      RS                   Residual Soil              no longer evident; there is a large chance in volume but the soil has not been significantly
                                                      transported.
                                                      Rock is weathered to such an extent that it has ‘soil’ properties, i.e. it either disintegrates
      EW             Extremely Weathered              or can be remoulded, in water.
                                    Highly            Rock strength usually changed by weathering. The rock may be highly discoloured usually
           HW                                         by iron staining. Porosity may be increased by leaching, or may be decreased due to
                  Distinctly       Weathered
 DW                                                   deposition of weathering products in pores. In some environments it is convenient to
                  Weathered     Moderately            subdivide into Highly Weathered and Moderately Weathered, with the degree of
         MW
                                Weathered             alteration typically less for MW.
      SW              Slightly Weathered              Rock is slightly discoloured but shows little or no change of strength relative to fresh rock.
      FR                      Fresh                   Rock shows no sign of decomposition or staining.
Notes:
1. Highly weathered - Rock material affected by weathering to the extent that limonite staining or bleaching affects the
   whole of the rock material and/or other signs of chemical or physical decomposition are evident. Porosity and strength
   may be increased or decreased compared to the fresh rock usually as a result of iron leaching or deposition. The colour
   and texture of the original rock material may no longer be recognisable.
2. Moderately weathered - Rock material affected by weathering to the extent that staining extends throughout the
   whole of the rock material and the original colour of the fresh rock may no longer be recognisable.
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