The Bi-directional Static Load Test ("Bi-Directional method") is a well-known static load testing method that uses a time and space saving approach of loading the pile resistance from the a mid-pile or near-toe position instead of top-loading. Whether in low headroom situation or within a busy intersection, in the middle of the river the Bi-Directional Static Load Test has risen to every challenge. Widely adopted in the US for bored pile, this method is gaining wide acceptance for its many advantages.

BENEFITS AND ADVANTAGES
Mobility & Space Efficiency
Eliminates the need for overhead beams or reaction piles.

 

Time Efficiency
It only takes hours to prepare a shaft for the installation of the premanufactured Bi-Directional pressure cell.

Precision Testing
Simple to conduct, the Bi-directional method provides engineers with separate data on the end-bearing and frictional resistance of the shaft.
 
Versatility
The Bi-Directional Static Load Test is useful on battered piles and sloping or belled shafts. Each shaft can be reused to carry working loads after test is completed. This is easily done by grouting the test system.
 
Testing Methodology
A hydraulically-driven, high-capacity, sacrificial pressure cell is pre-installed in a test pile. Loading is applied in two equal opposite directions: upwards against side shear of upper section and downward against soil resistance of the lower portion.

Test Results
The effectiveness and wealth of information yielded by the Bi-Directional Static Load Test are the reasons why more engineers and contractors are turning to the method. Since the end-bearing and upward shear resistance are measured and independently, there is no guesswork in how much load was carried by each component. Testing is typically performed until the ultimate capacity in either shear or end-bearing is reached to determine the maximum pile capacity. The addition of strain gages within the shaft can help to determine the distribution of load throughout the shaft length. The speed and accuracy of testing have made the Bi-Directional Static Load Test a valuable tool during value engineering and the redesign of projects.

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