Brief of The static pile load Test

The static pile load test is the most common method for testing the capacity of a pile and it is also considered to be the best measure of foundation suitability to resist anticipated design loads.Procedures for conducting axial compressive load tests on piles are presented in ASTM D 1143 — Standard Test Method for Piles under Axial Compressive Load.  

The pile load test can take a considerable amount of time and effort to properly set-up. Thus only one or two load tests are often recommended for a particular site.

Fig:-01

The location of the pile load tests should be at the most critical area of the site, such as where the bearing stratum is deepest or weakest. The first step involves driving or installing the pile to the desired depth. In Fig.01, the small arrows point to the concrete 

 

Fig:-02

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piles that have been installed and are founded on the bearing strata. The next step is to install the anchor piles, which are used to hold the reaction frame in place and provide resistance to the load applied to the test piles. The most common type of pile load test to determine its vertical load capacity is the simple compression load test. A schematic set-up for this test is shown in Fig. 02 and includes the test pile, anchor piles, test beam, hydraulic jack, load cell, and dial gauges. Figure 03 shows an actual load test where the reaction frame has been installed on top of the anchor piles and the hydraulic loading jack is in place. A load cell is used to measure the force applied to the top of the pile. Dial gauges, such as shown in Fig.04, are used to record the vertical displacement of the piles during testing. As the load is applied to the pile, the deformation behavior of the pile is measured. The pile is often subjected to a vertical load that is at least two times the design value. In most cases, the objective is not to break the pile or load the pile until a bearing capacity failure occurs, but rather to confirm that the design end-bearing parameters used for the design of the piles are adequate. The advantage of this type of approach is that the piles that are load-tested can be left in-place and used as part of the foundation. Figure 05 presents the actual load test data for the pile load test shown.

Fig:-04

Fig:-05