Example Mackintosh Probe Test

MACKINTOSH PROBE TEST GENERAL One of the most common types t ypes of probing is Mackintosh Probe. The purpose p urpose of Mackintosh Probe is to determine bearing capacity of the soil to withstand the loading. The Mackintosh  prospecting tool consists of rods which can be threaded together with barrel connectors and which are normally fitted with a driving point at their base, and a light hand-operated ha nd-operated driving hammer at their top. The tool provides p rovides a very economical method of determining the thickness of soft deposits such as peat. The driving point is streamlined in longitudinal section with diameter of 25mm. The drive hammer has a total weight of about 4.5kg. The rods are 1.2m long and 13mm diameter. The device is often used to provide a depth profile by driving the point and rods into the ground with equal blows of the full drop height available from the hammer: the number of blows for each 0.3m of penetration is recorded. When small pockets of stiff clay are to be  penetrated, an auger or a core tube can be substituted for the driving point. The rods can be rotated clockwise at ground level using a box spanner. Tools can be pushed into or pulled out of the soil using a lifting/driving tool. Because of the light ha mmer weight the Mackintosh Probe is limited in the depths and materials it can penetrate. p enetrate.

OBJECTIVE Mackintosh Probe test is carried out to determine the bearing capacity of soil. The result obtained from the test provides a rough estimation of the so il layer at a point.

APPARATUS :

-

Extension / Boring rod

- Wrench

- Rod coupling

-

Diving Head

- Drop Hammer

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Chalk

- Ruler

WORK PROCEDURE

1) Mark with each of the road with distance of 0.3m.

2) Join driving head at the end of boring rod.

3) Join drop hammer above of boring rod.

4) Place the rod at land and make sure that the rod is straight.

5) Raise and release 5kg drop hammer with specified height. 6) Record the number of blow every penetration of 0.3m. This test will end as if : i ) Had achieve its maximum blow ii) Had achieve penetration of 12m

DATA AND RESULT Depth(m)

No. of blow/0.3m

Cumulative no. of  blow Group 2 Group 1 Group 2 67 82 67 76 141 143 68 192 211 90 257 301 89 384 390 155 477 545 176 613 721 47 745 768 65 886 833 200 968 1033 1031 1141 1275 1337 1376 1426 1486 1531 1631 1661

0.0-0.3 0.3-0.6 0.6-0.9 0.9-1.2 1.2-1.5 1.5-1.8 1.8-2.1 2.1-2.4 2.4-2.7 2.7-3.0 3.0-3.3 3.3-3.6 3.6-3.9 3.9-4.2 4.2-4.5 4.5-4.8 4.8-5.1 5.1-5.4 5.4-5.7 5.7-6.0

Group 1 82 59 51 65 127 93 136 132 141 82 63 110 134 62 39 50 60 45 100 30

Discussion: 1. Calculate number of blow/0.3m:  Number of blow= Total of blow from A to B/Total of interval from A to B

For group 1  Number of blow=1661/20 =83.5 For group 2  Number of blow=1033/10 =103.3 2. Determine the value of bearing capacity by referring to the graph of standard  bearing capacity versus number of blow/0.3m (APPENDIX).

CONCLUSION Mackintosh Probe test is carried out to determine the bearing capacity of soil. The result obtained from the test provides a rough estimation of the soil layer at a point. As for the test that our did, there are a part when it has harder soil but the deeper we did the test (hammering the rod) the result (soil) become smoother. The best of our result (harder soil) is at 1.8m to 2.7m depth. Referring to the graph, the value of bearing capacity was determined. The ma in objective of our test is achieved.