1-22276-01 site plan

                                       NOTES RELATING TO THIS REPORT
                                                         September, 2019


uncertainties as to the original depth of the samples.               In a case where the test is discontinued short of full
Augering below the groundwater table has a lower reliability         penetration, say after 15 blows for the first 150 mm and 30
than augering above the water table. Various drill bits are          blows for the next 40 mm, the record shows:
attached to the base of the augers during the drilling. The
                                                                              15, 30/40mm
depth of refusal of the different bit types can provide
information as to the strength of the material encountered.          The results of the test can be related empirically to the
Generally the ‘TC’ bit (a tungsten carbide tipped screw type         engineering properties of the soil.
bit) is used.
                                                                     Occasionally, the drop hammer is used to drive 50mm
Wash Boring - The borehole is usually advanced by a rotary           diameter thin walled sample tubes (U50) in clays. In such
bit with water or fluid pumped down the hollow drill rods and        circumstances, it is noted on the borehole logs.
returned up in the space between the rods and the soil or
                                                                     A modification to the SPT test is where the same driving
casing, carrying the drill cuttings. Only major changes in
                                                                     system is used with a solid 600 tipped steel cone of the
stratification can be determined from the cuttings, together
                                                                     same diameter as the SPT hollow sampler. The solid cone
with some information from "feel" and rate of penetration.
                                                                     can be continuously driven for some distance in soft clays or
More accurate information on soil strata is gained by regular
                                                                     loose sands, or may be used where damage would
testing and sampling using the Standard Penetration Test
                                                                     otherwise occur to the SPT. The results of this Solid SPT are
(SPT) and undisturbed thin walled tube samples (U50).
                                                                     shown as "Nc" on the borehole logs, together with the
Mud Stabilized Drilling - Either Wash Boring or Continuous           number of blows per 150 mm penetration.
Core Drilling can use drilling mud as a circulating fluid to
                                                                     Cone Penetration Tests - Test Method - Cone Penetration
stabilize the borehole. The term "mud" encompasses a range
                                                                     Tests (CPT) are carried out in accordance with AS 1289 Test
of products ranging from bentonite to polymers such as
                                                                     6.5.1-1999, using an electrical friction-cone penetrometer.
Revert or Biogel. The mud tends to mask the cuttings and
reliable identification is only possible from regular intact         The test essentially comprises the measurement of
sampling (e.g. from SPT and U50 samples) or from rock                resistance to penetration of a cone of 35.7 mm diameter
coring, etc.                                                         pushed into the soil at a rate of 10-20 mm per second by
                                                                     hydraulic force. The resistance to penetration is recorded in
Continuous Core Drilling - A continuous core sample is
                                                                     terms of pressure on the end area of the cone (cone
obtained using a diamond or tungsten carbide tipped core
                                                                     resistance, qc, in MPa) and friction on the side of the 135 mm
barrel. Provided full core recovery is achieved (which is not
                                                                     long sleeve immediately above the top of the cone (friction
always possible in very weak rocks and granular soils), this
                                                                     resistance, fs, in kPa). These forces are measured by
technique provides a very reliable method of investigation.
                                                                     electrical transducers (strain gauges) within the cone device.
In rocks, NMLC coring (nominal 52 mm diameter) is usually
                                                                     The ratio between friction resistance and cone resistance is
used with water flush. The length of core recovered is
                                                                     also calculated as a percentage, i.e.-
compared to the length drilled and any length not recovered
                                                                                             𝑭𝒓𝒊𝒄𝒕𝒊𝒐𝒏 𝑹𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆, 𝒇𝒔 (𝒌𝑷𝒂) 𝒙 𝟏𝟎𝟎
is shown as CORE LOSS. The location of losses is                     Friction Ratio (FR) =
                                                                                                 𝒄𝒐𝒏𝒆 𝒓𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆, 𝒒𝒄 (𝒌𝑷𝒂)
determined on site by the supervisor. If the location of the
loss is uncertain, it is placed at the top end of the run, when      The friction ratio, FR, is generally low in sands (less than 1%
the core is placed in a storage tray and recorded on the log.        or 2%) and generally higher in clays (say 3% or more). The
Standard Penetration Tests - Standard Penetration Tests              interpretation of sandy clays, clayey sands and material with
(SPT) are used mainly in non-cohesive soils, but can also be         a high silt content is more difficult, but intermediate values
used in cohesive soils, as a means of indicating density or          (between 1% and 3%) would be expected. Highly organic
strength. The test procedure is described in Australian              clays and peats generally have a friction ratio in excess of
Standard 1289, "Methods of Testing Soils for Engineering             5%.
Purposes" - Test 6.3.1.                                              Static cone data is recorded in the field on disc for later
The test is carried out in a borehole by driving a 50mm              presentation using computer aided drafting.
diameter split sample tube with a tapered shoe, under the            The equipment can be operated from any conventional drill
impact of a 63 kg hammer with a free fall of 760 mm. It is           rig. A total applied load in the range of 4 to 10 tonnes is
normal for the tube to be driven in three successive 150 mm          required for practical purposes, although lighter loads may
increments and the 'N' value is taken as the number of blows         be used. The cone penetrometers are available with various
for the last 300 mm, the upper 150 mm being neglected due            capacities of cone resistance ranging up to 100 MPa for
to possible disturbance from the drilling method. In dense           general purpose investigations, while a range of 0 to 10 MPa
sands, very hard clays or weak rock, the full 450 mm                 can be used where more sensitive investigations of soft clay
penetration may not be practicable and the test is                   are required.
discontinued at a reduced penetration.                               The cone resistance value provides a continuous measure of
In the case where full penetration is obtained with successive       soil strength or density, and together with the friction ratio,
blow counts for each 150 mm of, say 4, 6 and 7 blows, the            provide very useful indications of the presence of narrow
record shows,                                                        bands of geotechnically significant layers such as thin, soft
                                                                     clay layers or lenses of sand which might otherwise be
         4, 6, 7           N = 13                                    missed using conventional drilling methods.