35 of 49 Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 05: Earth Works, Pipe Works and Ground Improvement  5.4.6.2 Types of piles  5.4.6.3 Design of piles  5.4.6.4 Preliminary test piles  After the Engineer has approved the Contractor’s proposals and calculations for the proposed piling  system preliminary test piles shall be constructed as instructed by the Engineer. These shall be loaded  to 2.0 times the working load to prove the design and system and to demonstrate that the safe load re- quirements can be achieved by the piling method proposed.  5_Vol3_d4.3_Section 5 Earth and pipe works_en_GIR_rev6.docx  Pile spacing shall be limited to a minimum value of 3*D (D is maximum pile dimension). Otherwise,  the group effect shall be considered to reduce the bearing capacity and increase in settlement by con- sidering type of soil. The average compressive stress in the concrete of bearing piles under working load shall not exceed  25% of the characteristic cube strength at 28 days, calculated on the total cross sectional area of the  pile shaft.  Where piles in place are subjected to handling, stacking and pitching or bending moments and/or shear  forces, these shall be combined with the vertical loads (either in compression or tension) to satisfy the  design requirements.  These settlements shall include both permanent and elastic deflections. Measurement of the settlement  shall be made on first achieving the specified load. Measurement of the settlement shall be made at the  point of application of the load.  Working load Allowable settlement 8 mm  1.5 x working load Allowable settlement 10 mm  2 x working load  Allowable settlement 12 mm  The piles shall be of sufficient cross-section and length to sustain loads specified without settlement  exceeding the following:  For earthquake loading (lateral loadings) , the reactions and displacement of the pile group supporting  a structure shall be analysed in 3-dimensions and the displacements in horizontal direction shall be  checked. The lateral bearing capacity should be assessed by treating the soil around as ultimate limit  state (limit equilibrium) and/or elasto-plastic (p-y curves).  The permissible load of piles shall be modified where necessary to allow for particular conditions:  piles in close proximity or in groups, soil strength, groundwater level, and other relevant factors.  If pile tests are carried out, capacity of the piles shall be calculated according to the safety factors giv- en in Section 5.4.6.14 instead. In this case, working load bearing capacity and extreme load bearing  capacity shall be the taken the same value.  Piles shall be generally designed in accordance with appropriate DIN standard and the materials and  work shall conform to the requirements of the Employer’s Requirements. Piles shall be designed to  sustain the specified loads with settlements not exceeding those specified. Allowance shall be made in  the design for the incidence of negative skin friction where appropriate and for resisting the necessary  tensile forces due to the swelling and heave of any soil stratum. Piles shall be designed to have a bear- ing capacity of at least 2.5 times the working load. In extreme cases (such as Earthquake loading case),  piles shall be designed to have a bearing capacity of at least 2.0 times the extreme load. Bearing piles shall be driven reinforced concrete, precast concrete or cast in-situ concrete piles. All  concrete shall be in sulphate resisting cement Type V. 