42 of 49 Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 05: Earth Works, Pipe Works and Ground Improvement  b) Trial Piles (Test Piles)  The number of trial piles required to verify the design shall be selected on the following aspects:   the ground conditions and their variability across the site   type of structure   documented evidence of the performance of the same type of pile in similar ground conditions   the total number and types of piles in the foundation design  The number of test piles shall be minimum 2, with different lengths or diameters. In determination of  test loads and test pile length, designer shall consider the estimated load amount that each working pile  will carry as well as the capacity of the hydraulic jacks and pumps that will be used in the tests.  The ground conditions at the test site shall be investigated thoroughly. The depth of borings or field  tests shall be sufficient to ascertain the nature of the ground both around and beneath the pile tip. It  shall include all strata likely to contribute significantly to pile deformation behaviour, at least 5 times  the diameter beneath the pile tip, unless sound rock or very hard soil is found at a lesser depth.  The method used for installation of the test piles shall be fully documented in accordance with section  5.4.6.4.  c) Working Piles  Dynamic Load Tests  a) General  5_Vol3_d4.3_Section 5 Earth and pipe works_en_GIR_rev6.docx   bearing capacity   toe resistance and skin friction   maximum compression stress, acceleration, velocity and displacement   maximum tension stress in pile  In the CASE method or similar the following data shall be registered and reported:  In a dynamic load test the pile is instrumented with accelerometers and strain gauges. The gauges are  connected to a recording and data processing device. During blows on the pile signals from the gauges  are recorded and processed for assessment of pile bearing capacity. The data processing will be one of  two kinds, either simple or signal matching (CASE or similar program).The simple method gives in- stant results while signal matching is more time consuming (hours).  Dynamic load tests may be used as an indicator of the consistency of the piles and to detect weak  piles.  The results of dynamic load tests may be used for design provided an adequate site investigation has  been carried out and the method has been calibrated against static load tests on the same type of pile,  of similar length and cross-section, and under comparable soil conditions.  Dynamic load tests shall be carried out in accordance with ASTM D 4945-89 ”Standard Test Method  for High-Strain Dynamic of Piles”.  The load applied to the working test piles shall be at least equal to the design load governing the de- sign of two foundations.  The selection of the working test piles should be prescribed in the contract documents.  The number of working pile load tests shall be selected on the basis of the recorded findings during  construction. 