Insitu Testing

InsituTesting 

Insitu tests are used to obtain density or the shear strength of soils and valuable since can be carried out without disturbing the soils

Insitu Tests     

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Standard Peniteration Test Vane Test Plate Bearing Test California Bearing Ration (CBR) Permeability tests, ground water level and ground water pressure test Geophysical Tests

Standard Penetration Test (BS 1377) This test is particularly useful for testing the resistance of sands and gravels under static or dynamic loading. This is made by driving a 35 mm dia split-barrel sampler into the soil by falling a standard weight (65 KG from 760 mm). The test is used to establish relative density of soil. Sands No of Blows

0-4 4-10 10-30 30-50 Over 50

Relative Density

Very loose Loose Medium Very Dense

Clays Notes

No of Blows

Relative Density

0-4 2-4 4-8 8-15 15-30 Over 50

Very Soft Soft Medium Stiff Very Stiff Hard

Compressive Strength(KN/m2)

0-24 24-49 49-98 98-196 196-392 Over 392

Vane Test (BS1377) This test measure the shear strength of soft cohesive soils insitu. The vane is pushes into the soft clay and rotated by hand at a constant rate. The amount of torque necessary for rotation is measured and shear strength of soil is calculated. The test can also be used to measure the remoulded strength of soil. Test is usually carried out in uniform cohesive saturated clay and advantages is that test can be performed with disturbing the soil.

Plate Bearing Test (BS 1377) This test is means of providing insitu data on the behaviour of soils at foundation level. The test consists of excavating pit to proposed foundation level and then loading a steel plate, ranging from 300 to 1000mm in dia. The loads can be applied in increments by hydraulics jacks or by placing concrete blocks. Settlement after each increment is recorded and plotted on time graph. Load is noted which gives penetration of 15 % of plate width, called ultimate load.