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Republic of the Philippines
DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS
CENTRAL OFFICE
Manila

AUG 1 0 2022
Department Order ) SUBJECT: Bi-Directional Static Load Test for
) Bored Piles

No. 206 _
)
)
Series of 2022
0\ \0 lID I~D22.

In order to provide an alternative testing method for bored piles and to ensure quality and
soundness of foundations for various infrastructure projects, the use of Bi-Directional Static
Load Test (BDSLT) is hereby prescribed for guidance of DPWH Implementing Offices.

The BDSLT on bored piles utilizes a specialized hydraulic jack assembly, embedded at an
equilibrium resistant point (predetermined based on geotechnical investigation results). Said
hydraulic jack assembly is then pressurized to apply loads onto the pile in both upward and
downward directions. Standard materials, equipment, test procedure, and results
interpretation shall conform to ASTM 08169 - 18 ''Standard Test Methods for Deep
Foundations Under Bi-Directional Static Axial Compressive Load/~ Refer to Annex ')1 "for the
detailed test procedure.

This alternative deep foundation testing method may be used for bored piles such as but not
limited to:

1. Bored piles having diameters of 2.5 meters or greater; or those with bored pile demand
load greater than 15,000 kN.
2. Bored piles near existing structures, where High-Strain Pile Dynamic Test using Pile
Dynamic Analyzer (PDA) may cause disturbance to the adjacent foundation/structural
members.
3. Deep offshore piles, at sites where installation of cofferdams for the conduct of PDA is
not feasible.

This Order supplements Department Order No. 37, series of 2016, and shall take eff.ect
immediately.

5.1 BSR/ECM
Departrrent 01 Public Works and Highways
Office 01 the Secretary

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 Annex "A" of D.O. No. .21%. 5: 2022
Page 1 of 4

ANNEX "A"

TEST PROCEDURES FOR BI-DIRECTIONAL STATIC AXIAL

COMPRESSIVE LOAD TEST (BDSL T)

PRINCIPLES

Bi-Directional Static Load Test (BDSLT) tests deep foundations such as bored piles to
determine the resistance distribution along its length and assess the pile behavior under static
loading. The test method measures the axial displacement of a single deep foundation loaded
in bi-directional static axial compression using an embedded bi-directional jack assembly. The
bi-directional axial compressive load test provides separate, direct measurements of the pile
side shear mobilized above an embedded jack assembly and the pile end bearing plus any
side shear mobilized below the jack assembly.

The maximum mobilized pile resistance equals two times the maximum load applied by the
jack assembly. Test results also provide information used to assess the distribution of side
shear resistance along the pile, the amount of end bearing mobilized at the pile bottom, and
the long-term load-displacement behavior. The main purpose of the BDSLT is to measure the
displacement at design load and maximum test load (determined by the foundation engineer)
stages, and to assess structural stability by checking whether the test results are within the
specified design criteria.

The test shall be performed by a qualified testing personnel in accordance with the "ASTM
D8169jD8186M-18" Standard Test Method for Deep Foundations Under Bi-Directional
Static Axial Compressive Load.

TEST PILE PREPARATION

For cast-in-place piles constructed by excavating an open hole in the ground such as drilled
shafts or bored piles, position the jack assembly at the desired location within the pile prior
to placing the concrete. Use a steel reinforcement cage and ensure that the location and
orientation of the setup during concrete placement will be maintained. Obtain sound concrete
around the assembly by using a fluid concrete mixture, placing concrete at a slow and steady
rate, and providing adequate clearance around the jack assembly to avoid restricting concrete
flow and trapping any sediments. The jack assembly should be placed at a minimum distance
of one-half pile diameter above the pile bottom. Provide a minimum clearance of the lesser of
75 mm or 8 times the diameter of the largest coarse aggregate, between the jack and the
sidewalls of the excavation

Typical schematic of an embedded bi-directional cell assembly is shown in Figure 1. The

resultant line of force of the bi-directional cell assembly shall coincide with the central axis of
 Annex "A" of D.O. No. 20(P. s'.,2022
Page 2 of 4

the foundation element During initial bi-directional cell pressurization, a fracture plane will
form through the concrete surrounding the bi-directional cell assembly, and the pile
reinforcement and instrumentation shall not restrain the subsequent expansion of the
assembly after the fracture occurs. As indicated below, different types of deep foundations
require different methods of bi-directional cell installation.

Hydraulic Pump
Datalogger
High-Pressure Hydraulic
Hoses or Pipes
~ Compression
Transducer
r Digital Survey DeviCE
(or Reference Beam
and Top of Shaft
Gages)

Electronic Displacement Indicator

(or bottom-plate telltale)
to Measure Jack Expansion
Break in Pile Concrete

Figure 1. Schematic of Bi-Directional Load Test Instrumentation

The assembly shall comprise of bi-directional cell and steel bearing plates. Fabrication of the
bi-directional cell assembly may be carried out on site or at the piling contractor's workshop,
where the bi-directional cell'will be accurately positioned and welded to steel bearing plates
above and below the bi-directional cell. Fabrication drawings for the bi-directional cell
assembly for bearing plates are included Figure 2 below:

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Figure 2. Bi-Directional Cell Assembly

 Annex "A" of D.O. No. 20(" s.,C 2022 •
Page 3 of 4

A single level bi-directional cell assembly will be installed in the test pile along with the
necessary hydraulic system and instrumentation attached to the steel reinforcing cage. The
final bi-directional cell assembly position is subjected to the approval of the Implementing
Office upon recommendation of the geotechnical design engineer. For the purpose of fully
mobilizing the axial compressive capacity, it is recommended to locate the bi-directional cell
assembly at a location within the pile where the capacity above the assembly equals the
capacity below it. The position of bi-directional cell assembly herein is a preliminary estimate
based on assessment of the soil exploration/geotechnical investigation conducted.

To ensure that no damage occurs to the bi-directional cell during handling or lifting the
assembly, temporary reinforcement shall be installed across the bi-directional cell
assembly. Two or more pieces of reinforcing steel will be welded between the top and bottom
of the bearing plates as to temporarily reinforce the bi-directional cell assembly. Temporary
reinforcement at the bi-directional cell assembly will be cut once the cage is vertical and is
being lowered into the excavated bore, such that no steel crosses the bi-directional cell
opening level.

Install a minimum of two hydraulic hoses or pipes (input and return) extending from top of
pile to the jack assembly. Jacks directly connected together within an assembly shall be tested
together to verify flow continuity and to check for pressure leaks.

EQUIPMENT

1. Bi-Directional Jacks
2. Pressure Gauges
3. Pressure Sensors
4. Strain Gauges
5. Pressure Gauge
6. Hydraulic Pump
7. Hydraulic Hoses and Fittings
8. Digital Survey Levels
9. Data Taker Geologger
10. Laptop Computer
11. Bearing Plates / Stiffeners
12. Reinforcement Cage.

PILE TESTING PROCEDURE

Use the embedded jack assembly to apply load to the test pile. The resulting test load applied
to the pile is twice the load measured in the jack assembly.

Bi-Directional Load Test may commence when minimum pile compressive strength as required
by the project specifications is reached. Apply at least ten (10) equal increments of jack
assembly load to the pile, with each increment being no more than 5% of the maximum
specified test load. The load change from anyone increment to another should not deviate
from any other preceding increment by more than 5%, and the maximum speCified jack
assembly load will be 50% of the maximum specified test load.
 Annex "A" of D.O. No'. ~ s: 2022
Page 4 of 4

Immediately after the completion of the final readings for each load increment, add the next
load increment in a continuous manner within two (2) minutes. If significant movement occurs
above or below the jack assembly, extend the loading time to apply the load increment to the
opposing portion of the pile. Add load increments until half of the maximum specified test
load, maximum expansion, or load capacity of the jack assembly is reached. Also observe if
continuing, progressive expansion of the jack assembly with no significant increase in jack
pressure is present.

Upon attaining the load, keep the load constant for at least four (4) minutes but not more
than 16 minutes. Remove the load in five (5) to ten (10) approximately equal decrements,
keeping the load constant for 4 - 16 minutes as well. The geotechnical design engineer may
specify a longer time interval for the final load increment to assess long-term creep, and for
the final zero unload to assess rebound behavior.

ACCEPTANCE AND REJECTION

The load will be removed and testing is considered completed when either of the following
cases occur:

1. Maximum required test load has been applied

2. Load capacity of the jack assembly is reached
3. Maximum settlement is exceeded

The final analyzed allowable bearing capacity should satisfy the design load and the
displacement measured should not exceed 25 mm.

REPORTS

As a minimum, record the following test information:

1. Description of test conducted including methodology, equipment, and photographs.

All relevant project information shall be indicated as well.
2. Complete test data and description of every procedure conducted (e.g., jack
pressure, load from load sensing device, pile movement, jack assembly movement,
plot of load versus plate movement, jack calibration, among others)
3. Evaluation and Recommendations

References:

1. Standard Test Methods for Deep Foundations Under Bi-Directional Static Axial Compressive Load. ASTM
D9169M-18. American Society for Testing and Materials. 2018
2. Bi-Directional Static Axial Compressive Load Test for Piling
https://www.civil-engineers-2020.com/2020/09/bi-directional-static-axial-compressive.html