Reference Document - Acid Sulfate Soil Report 11_2023- OPW23_0189 · OPW26/0094

                 The borehole can be stabilised through the use       using a Cone Penetrometer in            general
                 of drilling mud as a circulating fluid. The term     accordance with AS 1289 6.5.1, 1999.
                 ‘mud’ encompasses a range of products
                 ranging from bentonite to polymers such as           In the tests, a 36mm diameter rod with a
                 Revert or Biogel.                                    conical tip is pushed continuously into the soil,
                                                                      the reaction being provided by a hydraulic
                 Continuous Core Drilling: A continuous core          ram system. Measurements are made of the
                 sample is obtained using a diamond tipped            end bearing resistance on the cone and the
                 core barrel. This technique provides a reliable      fractional resistance on a separate 135mm
                 (but    relatively   expensive)    method     of     long sleeve, immediately behind the cone.
                 investigation. In rocks, an NMLC triple tube         Pore Pressure is recovered through a pore ring
                 core barrel is used, which gives a core of about     located either within, or more usually
                 50mm diameter. The length of core recovered          immediately behind the cone/tip.
                 is compared to the length drilled and any
                 length not recovered is shown as CORE LOSS.          As penetration occurs (at a rate of
                                                                      approximately 20mm per second) and data is
                 Standard       Penetration    Tests:     Standard    recorded every 20mm of penetration, the
                 Penetration Tests (SPT) are used mainly in non-      results are presented graphically.
                 cohesive soils, but can also be used in cohesive
                 soils as a means of indicating density or            The information     provided     on    the   plot
                 strength and also of obtaining a disturbed           comprises:
                 sample. The test procedure is described in
                                                                             Cone resistance – expressed in mPa
                 Australian Standard 1289, “Methods of Testing
                                                                             Sleeve friction – expressed in kPa
                 Soils for Engineering Purposed”, Test 6.3.1.
                                                                             Friction ratio – the ratio of sleeve
                 The test is carried out in a borehole by driving a           friction to cone resistance expressed as
                 50mm diameter split sample tube with a                       a percentage.
                 tapered shoe, under the impact of a 63kg                    Pore pressure in kPa
                 hammer, with a free fall of 760mm. The sample               Tilt of probe (in degrees).
                 is driven in three successive 150mm increments
                 and the ‘N’ value is taken as the number of
                                                                      The ratios of the sleeve resistance to cone
                 blows for the last 300mm. In dense soils, hard
                                                                      resistance will vary with the type of soil
                 clays or weak rock, the full 450mm penetration
                                                                      encountered, with higher relative friction in
                 may not be practicable and the test is
                                                                      clays than in sands. Friction ratios of 1% to 2%
                 discontinued.
                                                                      are commonly encountered in sands and rising
                 The test results are reported in the following       to 2% to as high as 8%, and higher in organic
                 form:                                                soils.   Soil descriptions based on cone
                                                                      resistance and friction ratios are only inferred
                         In the case where full penetration is       and must not be considered as exact.
                          obtained with successive blow counts
                          for each 150mm of , say, 4, 6 and 7         Stratification can be inferred from the cone
                          blows, as                                   and friction traces and from experience and
                          N = 13                                      information from nearby boreholes, etc. Where
                          4, 6, 7                                     shown, this information is presented for general
                         In a case where the test is discontinued    guidance, but must be regarded as
                          short of full penetration, say after 15     interpretive.
                          blows for the first 150mm and 30 blows
                                                                      Dynamic Cone Penetrometers:
                          for the next 40mm, as
                          N > 30
                                                                      Dynamic Cone Penetrometer (DCP) tests are
                          15, 30/40mm
                                                                      carried out by driving a 16mm diameter rod
                                                                      into the ground with a 9kg sliding hammer
                 Cone Penetrometer Testing (CPT): Cone
                                                                      dropping 510mm and counting the blows for
                 Penetrometer Testing with or without pore
                                                                      successive 100mm increments of penetration.
                 pressure measurement (CPTu) is carried out




Document Set ID: 22828362
Version: 1, Version Date: 26/02/2024