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The purpose of this test is to determine theload vs. settlement of the sub-soil under specified maximum loads, at a specifiedelevation and location and estimate bearingcapacity.Design Engineers need to know the bearingcapacity of soil underneath. Results from thetest can be used as design parameter or usedto confirm the design assumption .

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ApparatusCircular loading plate (size 300mm in diameter) andextension plates.Hydraulic jack for applying the load with a 10 tonnepressure gauge.Reference beams provided with anchors and clamps.

Dial gauges (indication 30x100x0.01mm of displacement) with adjustable holders -2 numbers.Reaction load or counterweight (by an excavator). Totalcounterweight should be at least 105 greater than the

anticipated maximum test load.

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Testing ProcedureSelect test location and excavate to a depth, the point wherethe real foundation will be constructed, if possible . If the

test is performed in a test pit, width of the pit should be atleast 4 to 5 times of plate diameter .Apparatus Setting out :

- Level the test point and ensure that any materialloosened or softened be removed so that the area for the

plate is generally level.- Place the loading plate with its center at the test point,

ensuring that is level.- An excavators provides the required reaction for the test

pressures.

- Anchor the reference beams at distances and heightssuitable for holding the dial gauges into the ground notaffected by the loading system of the test.

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- Install the two dial gauges with their plungers verticallysitting at two points on the peripheral area of a boarder extension

plate. The two gauges are at both sides with reference to thecenter of plate.- Adjust the centers of the loading plate, jack base and the

reaction load-system all in vertical alignment.Apply the load to plate in step by means of hydraulic jack pushingagainst the counter weight until reaching the maximum test load. Ateach increment (step) the pressure shall be maintained as near aspossible constant.Read and record the load of every step from pressure gauges.Read settlement from the dial gauges.Unloading should also be done in the backward steps.

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Cycle of Loading and Unloading

Note: 1.Dial gauge readings will be taken for every maintain load at 0,1,2,3,5,10,15 mins. of elapsed time of loading

2. and 0,1,2,3,5,10,15, 60 mins. of elapsed time at maximum load.

Step LOAD (Ton) Time (min)

I 0.0 0

II 0.5 15

III 1.5 15

IV 2.5 15

V 3.5 15

VI 4.5 15

VII 5.5 15

VIII 3.5 15IX 1.5 15

X 0.0 15

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Bearing Plate

Reference Beam

Dial Gauge

Hydraulic Jack

Counter Weight

Pressure Gauge

ILLUSTRATION OF PBT SET UP