Compiled Reference Documents - MCU20/0084.01 (As Published)

            LANDSLIDE HAZARD                                                                            MACGREGOR & TAYLOR



                                                                                                                               Appendix B1

            LANDSLIDE FREQUENCY ANALYSIS                                                                    Analysis No.:

                    NATURAL SHALLOW LANDSLIDES


            LOCATION:                                  Site No.         Site name:


              1 Basic Frequency                                          6 Concentration of surface water


              2 Slope Angle                                             Site                                                Level Factor
                                                                          Ridge                                              L     0.7
            Site                                        Level Factor      Crest                                              M     0.8
               Less than 5 degrees                       L     0.1        Upper slope                                        M     0.9
               Between 5 and 15 degrees                  M     0.5        Mid slope                                          H     1.2
             ✔ Between 15 and 30 degrees                 M     0.8      ✔ Lower slope                                        H     1.5
               Between 30 and 45 degrees                 H     1.2
               More than 45 degrees                      M     0.8       7 Evidence of groundwater

              3 Slope Shape                                             Site                                                Level Factor
                                                                               None apparent                                  L    0.7
             Site                                       Level Factor    ✔ Minor moistness                                    M     0.9
               Crest or ridge                            L     0.7             Generally wet                                  H    1.5
             ✔ Planar                                    M     0.9             Surface springs                               VH     3
               Convex                                    M     0.9
               Concave                                   H     1.5       8 Evidence of instability

              4 Site geology                                            Site                                                Level Factor
                                                                        ✔ No sign of instability                              L    0.5
             Site                                       Level Factor           Trees bent                                     H    1.5
                    Volcanic rock                        H     1.1             Minor irregularity                            VH     2
             ✔ Sedimentary rock                          M      1              Major irregularity                            VH     5
                    Low grade metamorphic rock           M      1              Scarps                                        VH    10
                    High grade metamorphic rock          L     0.9
                    Granitic rock                        M      1              Summary
                                                                                                                                 Factor
              5 Material strength                                        2 Slope Angle                                            0.8
                                                                         3 Slope Shape                                            0.9
             Site                                       Level Factor     4 Site geology                                            1
               Rock at surface                           VL    0.1       5 Material strength                                      0.9
               Residual soil < 1 m deep                   L    0.5       6 Concentration of surface water                         1.5
             ✔ Residual soil 1-3 m deep                  M     0.9       7 Evidence of groundwater                                0.9
               Residual soil >3 m deep                   H     1.5       8 Evidence of instability                                0.5
                    Colluvial soil < 1 m deep            H        1.5
                    Colluvial soil 1-3 m deep            VH       2      9 Relative Frequency (2x3x4x5x6x7x8)                     0.44
                    Colluvial soil > 3 m deep            VH       4
                    Fill (slope regrading)               VH       5            Site Frequency (1 x 9)                             0.44




            60                                  Australian Geomechanics September 2001
Document Set ID: 22574699
Version: 1, Version Date: 07/09/2023