Page 29 - BUKU PROGRAM SEMINAR SPESIFIKASI PIAWAI JKR KERJA GEOTEKNIK

INSTRUMENTED PILE LOAD TEST ON SOFT GROUND

ABSTRAK

Piles are used to transfer load to underlying a stronger soil layer when an
upper soil layer is highly compressible and too weak to support the load
transmitted by the superstructure. By using a static formula an estimated
value of the ultimate bearing capacity of a typical pile is obtained, but the
accuracy being largely dependent on the reliability of the formula and the
soil strength data to which it is applied. The actual ultimate bearing
capacity of any particular pile will differ from this value in so far as the soil
surrounding it has properties different from those used in the calculation.
Due to the customary practice and compliance with regulatory
requirements, pile load tests are almost always required. The provision of
pile load tests allows the engineer to verify design parameters, design
more economical piles, check the quality of materials and workmanships,
and ultimately show the performance meets load-settlement
requirements. Also, it is important to understand the difference in
development rate for shaft friction and end-bearing.

This technical paper presents preliminary pile load test measures stress–
strain transferring in instrumented piles embedded within the soft soil
layer been loaded with four times to their design working loads. Extensive
data are analysed to measure the changes in stress–strain in the
instrumented pile. The effect of loading and unloading stages on the pile’s
head and base settlement has been monitored, indicating that modulus of
elasticity in concrete pile, Ec, average strain, and unit skin friction changed
along the bored-pile based on the ground site conditions and stress
registered. A loading test on a pile is made for the purpose of finding the
settlement to be expected at the estimated working load, where the load-
settlement curve derived the pile load test is an important plot to assist
engineer in understanding the pile behaviour.

Keywords: instrumented pile load test; load-settlement; stress-strain; shaft
friction; end-bearing resistance

28 KERTAS TEKNIKAL