Appendix B- Geotechnical Investigation

Project No. 1
            115-17158
April, 2015
Ref: 1-17158,, 2015-04-08, BR VE
                               ER 1                                                                       Page
                                                                                                          P    |9
John Jamies son – GEOTECHNIC   CAL INVESTIGATION
                                               N - Proposed Resid
                                                                dence, 38 Park Cres
                                                                                  scent, Sunshine Bea
                                                                                                    ach




    5.5 Retaining
                g Walls

Retentioon systemss should be
                            e designed in accordance with AS
                                                           S 4678-20002 'Earth Retaining
                                                                               R
Structurres'

The late
       eral earth pressure from
                              m the active
                                         e pressure wedge,
                                                    w      whe
                                                             ere:-

           P           =           0.5 Ka H2

           P           =           active force
                                          f     resulta
                                                      ant acting at
                                                                 a a height of
                                                                            o H/3

                                   from the
                                          e base (kN//m run of wa
                                                                all)

                      =                             N/m3
                                   density of sand, kN

           H1          =           height of
                                          o wall (m)

           Ka          =           active pressure
                                          p        co
                                                    oefficient

Until the base of the wall is prevented from inwarrd movement by the sstrutting acttion, the
       nce of move
resistan          ement is proovided by th                         eneath wall ground, and by the
                                          he friction of the soil be
passivee resistance
                  e of the soil against the
                                          e vertical face of the tooe of the waall. The inte
                                                                                           ensity of
passivee resistance
                  e can be calculated fromm:-

           P           =           0.5 Kp  H22

           Kp          =                 e pressure ccoefficient
                                   passive

           H2          =           front fac
                                           ce of wall c ontributing to passive resistance ((m)

The late eral pressu
                   ure distributions shown  n in Figure 2 include hydrostatic ppressure an  nd show
typical ppressure disstributions due
                                  d to surc harge loadings. Due to possible llong term problems
with bloocking of grravel filters and drains and short term
                                                       t     storm conditions tthat could flood
                                                                                            f     the
fill behind retainingg walls, it is recomme ended that all retaining
                                                                   g walls be designed fo   or some
water p pressure disstribution. A suggeste  ed water prressure disttribution forr retaining walls
                                                                                             w     on
this site
        e would be one
                     o third he  eight water pressure.

For the calculation
                  n of sliding resistance,
                                r           base friction for walls without
                                                                    w       a keey may be taken
                                                                                          t     as
tan (2/3
       3 Ø). If the wall has a shallow basse key the shearing
                                                        s         resistance maay be basedd on tan
Ø. Refe er to Table 3 for the friction angle of sand.