Foundations to structures carry heavy loads, permanently imposed on them. The shorter the time that a test load is applied to a pile, the more complex becomes the interpretation of the test measurements into the pile’s behaviour under permanent load.
In order of decreasing time of load application, the load tests are:
- Maintained Load Test
- Constant Rate of Penetration Test
- Rapid Load Test
- Dynamic Load Test
Scroll down to use the diagram at the bottom of this page to get more information about each type of test.
LOAD TRANSFER TO SOIL DURING A PILE TEST
Regardless of the type of load test, the information obtained from the test is greatly increased by measuring (during the test) the force in the pile shaft at intervals along its length, using Strain Rods shown in the picture below here. From these measurements the mechanics of the transfer of load through: (i) friction along the shaft length; and (ii) end bearing can be seen. This information increases the confidence of the responsible engineer in the design and also (if the test is done at an early stage in the project) can enable economies in the pile design to be effected.
More detailed information is given in the document: “Method statement for the determination of the mechanics of pile behaviour during a load test on a bored pile”. Click here to access it.
Strain rods cast into a pile to determine shear stress distribution along the shaft and bearing stress under the base
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