PROBE MACKINTOSH TEST 1.0
INTRODUCTION The site investigation is the one thing that must be done before starting the
construction of the building. This is because the soil condition at the site need to be identifies to determine the suitable foundation use for the building and soil play a main role to support the load that come from the building and the building need a suitable foundation to transfer the load to the ground. Therefore, the investigation of soil need to be done to identify the type of soil to ensure the soil can carry the load.
Mackintosh/JKR probe test
This is a dynamic penetrometer test used to check the consistency of the subsoil. Mackintosh probe which has 30° cone penetrometer while JKR probes has 60° cone penetrometer. This is a light dynamic test and the cone is driven directly into the soil by driving a hammer 5 kg. Weight dropping through a free height of 280mm. The probe is unable to penetrate into medium strength soil and gravelly ground.
2.0
OBJECTIVE : •Collecting a disturbed soil sample for grain-size analysis and soil classification •Determine sub-surface stratigraphy and identity materials present •Evaluate soil density and in-situ stress conditions •Estimate geotechnical parameters
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PROBE MACKINTOSH TEST
3.0
THEORY : The main purpose of the test is to provide an indication of the relative density
of granular deposit, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples. The great merit of the test and the main reason for its widespread use is that it is simple and inexpensive. The soil strength parameters which can be inferred are approximate, but may give a useful guide in ground conditions where it may not be possible to obtain borehole samples of adequate quality like gravels, sands, silts, clay containing sand or gravel and weak rock. The usefulness of SPT results depends on the soil type, with fine-grained sands giving the most useful results, with coarser sands and silty sands giving reasonably useful results, and clay and gravelly soils yielding results which may be very poorly representative of the true soil conditions. This test method provides a disturbed soil sample for moisture content determination, for identification and classification purposes, and for laboratory tests appropriate for soil obtained from a sampler that will produce a large shear strain disturbance in the sample. Soil deposits contained gravels, cobbles or boulders typically result in penetration refusal and damage to equipment. This test method is used extensively in a great variety of geotechnical exploration projects. Many local correlations and widely published correlation which relate blow count, or N-value, and the engineering behavior of earthworks and foundations are available.
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PROBE MACKINTOSH TEST 4.0
APPARATUS No. 1.
picture
Name of apparatus Boring Rods
2.
Rod Couplings
3.
Lifting tools
4.
Penetration Cone
5.
Hammer
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PROBE MACKINTOSH TEST 6.
Wrench
7.
Ruler
8.
Marking tools
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PROBE MACKINTOSH TEST 5.0
PROCEDURE
1.
Equipment for the test are assembled.
2.
The boring rods and hammer are joint using the rod coupling. Grease is sweep up for an easy dissembles later.
3.
Distance of 0.3 m is measured and marked on the rod start from the tip of the cone.
4. The equipment is set up on the ground. 5.
The hammer is pulled until it reached the maximum. The hammer is dropped freely to driven the cone into the soils.
6.
The sum of the number of blows for penetration of 0.3 m is recorded in the data sheet.
7.
The hammer is taken off on the last 0.3 m of each rod and joined the existing rod with another rod and lastly the hammer. The blow is continued and stopped when: • The blow is more than 400 for 0.3 m penetration • The depth reached 15 m8.Pull the rods using lifting tools after the penetration reached the requirement.9.The equipment is dissembled and cleaned before storing.
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PROBE MACKINTOSH TEST 6.0
RESULT :
Energy Per Unit Area (N/m ² ) = 27972 DEPTH ( m ) NO OF BLOWS 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
CUMULATIVE NO OF BLOWS
256 160 86 144 48 24 19 14 11 22 25 21
256 416 502 646 694 718 737 751 762 784 809 830
Layer AB : Total number of blows from A to B
= 646 - 0 = 646 Total number of intervals from A to B = (1.2 – 0) / 0.3 =4 Number blows per 0.3 m = 646/ 4 = 161.5 Layer BC : Total number of blows from B to C = 751 - 646 = 105 Total number of intervals from B to C = (2.4– 1.2) / 0.3 =4 Number blows per 0.3 m = 105 / 4 = 26.25 Layer CD : Total number of blows from C to D
= 830 - 751 = 79 Total number of intervals from C to D = (3.6 – 2.4) / 0.3 =4 Number blows per 0.3 m = 79 / 4 = 19.75 7.0 1.
DISCUSSION The test is carried out first before the tests other sites before a construction
project initiated to ensure the land in accordance with the construction projector not. 6
PROBE MACKINTOSH TEST In addition, the small size and lightweight device that causes the work easy to handle and quick. 2.1
ADVANTAGES
The size of a small, lightweight device causing easily handled and speed work. Tests performed earlier than tests of other sites before a project underway. Information and data were obtained more quickly, easily and save time. The cost of handling, equipment and the use of relatively cheap. 2.2
DISADVANTAGES
Use limited in terms of the impact energy is too limited. Bearing capacity of soil foundation design is a development known only superficial. 3.
The probe testing hole to ensure the project is determined on-site project is
located right in the building. Also, make sure that the test holes are free of tree roots that can prevent devices from getting into the ground.4. The way to stamp the weight member to the weight and pressure will affect the number of entries into the ground rod. In addition, the possibility to be bent rod may also occur due to excessive load during stamping. Number of shock should also be the same as during the test run and the counter weight should also be taken at the proper height.
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PROBE MACKINTOSH TEST 8.0
CONCLUSION When we do this experiment, we managed to complete in 2 hour. When the
experiment is conducted, we learn how the probe mackintosh is conduct when the penetration of the boring rod penetrate to the ground. There were 4 boring rod use din this experiment. This experiment is conducted similar to piling work at construction site .We get the data and tabulate it into form. From that we learn how to calculate the data that we got. After the calculation is done, we plotted the graph from the calculation. Probe has a knocker that will be passed to suppress the cone into the soil to be tested. Total amount of knock every one foot or 300mm will be recorded. Into the test is limited to a maximum of 60 feet. Test results interpreted in the form of soil bearing strength. This value can be used in basic research as well as building other studies on soil strength. Probe is also often used to complement the data about the strength of the soil layer between the bore holes. This test is usually carried out at a distance of 30-50 feet. Interpretation of the bearing strength is made using a specified formula or using the graph. •If the value of knocking on 10, meaning very poor soil. •if knock between 10 to 40, sediment testing needs to be done. •Knocking over 40 marked the land is quite strong for the base building or other structure.
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