1.0.1 To unify technical requirements for testing pile under static load in harbour engineering, this specification is prepared as a reliable criterion for design, construction and acceptance of pile engineering.
1.0.2 This specification is applicable to testing of pile under static load in harbour engineering and may be complied with by reference for the testing of pile under static load for navigation buildings and hydraulic shipbuilding and repairing buildings.
1.0.3 This specification shall be used together with the current professional standard "Code for Pile Foundation of Harbour Engineering" (JTJ 254).
1.0.4 Testing of pile under static load in harbor engineering shall not only meet the requirements of this specification and the relevant requirements of the current national standard.
2 Terms and Symbols
2.1 Terms
2.1.1 Piles
Individual pile in pile foundation.
2.1.2 Pile static load testing
Testing of determining pile bearing capacity under the action of static load, including axial compression, axial pulling and horizontal static load tests.
2.1.3 Testing pile
A pile whose bearing capacity shall be determined.
2.1.4 Anchor pile
A pile to provide reactive force for the testing pile.
2.1.5 Reference beam
Beam used for setting observing apparatus.
2 .1.6 Reference pile
A pile to erect reference beam.
2.1.7 Engineering pile
Piles forming pile foundation of the structure.
2.1.8 Estimated maximum testing load
Maximum loading planned to load on the testing pile for the purpose of test.
2.1.9 Ultimate bearing capacity of pile
Maximum loading corresponding to the displacement when the pile approaches collapse behaviour under the action of static load or the displacement unfit for load bearing appears.
2.1.10 Axial reaction coefficient of piles
Settlement volume of pile top under the action of unit axial force.
2.2 Symbols
2.2.1 A——Cross-sectional area of pile body (m2).
2.2.2 bo——Conversion width of piles (m).
2.2.3 d——Pile diameter or pile width (m).
2.2.4 Ep——Elasticity modulus of pile body material (kPa).
2.2.5 ho——Distance from action point of horizontal load to mud surface (m).
2.2.6 H——Horizontal load (kN).
2.2.7 Ho——Horizontal force borne by piles by converting to mud surface elevation (kN).
2.2.8——Section inertia moment of pile body (m4).
2.2.9 kN——Horizontal subgrade reaction coefficient (kN/m3).
2.2.10 L——Pile body length (m).
2,2.11 m——Proportionality coefficient of horizontal subgrade reaction coefficient along with increased depth (kN/m4).
2.2.12 Mo——Moment borne by piles by converting to mud surface elevation (kN?m).
2.2.13 P——Horizontal subgrade reaction (kN).
2.2.14 Q——Axial compressed load acting on pile top (kN).
2.2.15 Qmax——Axial maximum compressed load acting on pile top (kN).
2.2.16 Qu——Axial ultimate compression capacity of piles (kN).
2.2.17 Qup——Axial up-pull load acting on pile top (kN).
2.2.18 S——Settlement volume of pile top (mm).
2.2.19 Sup——Up-pull volume of pile top (mm).
2.2.20 t——Testing duration (min).
2.2.21 T——Relative rigidity coefficient of piles (m).
2.2.22 Y——Horizontal displacement of pile at action point under the action of horizontal load (m).
2.2.23 Yo——Horizontal displacement of pile at mud surface elevation caused by mud surface deformation under the action of horizontal load (m).
2.2.24 Y1——Horizontal displacement of pile body at horizontal load action point caused by intersection angle at mud surface under the action of horizontal load (m).
2.2.25 Y2——Horizontal deformation of pile body at horizontal load action point caused by horizontal load supposing pile body at mud surface elevation is fixed (m).
2.2.26 Z——Soil layer depth (m).
2.2.27 θ——Pile top intersection angle under the action of horizontal load (rad)
2.2.28 θ0——Intersection angle of pile at mud surface elevation under the action of horizontal load (rad).
3 Axial Compression Static Load Testing
3.1 General Requirements
3.1.1 Axial compression static load testing may be used to determine axial ultimate compression capacity of testing pile or inspect axial pressure bearing capacity of engineering pile.
3.1.2 Testing to determine axial ultimate compression capacity of testing pile should be carried out before the design; and the testing to inspect axial compression bearing capacity may be carried out during engineering construction.
3.1.3 Testing to determine axial ultimate compression capacity shall be loaded to damage; the testing to inspect axial compression bearing capacity of engineering pile shall load to reach the design requirements at most.
3.1.4 Except special requirement specified in the design, the number of the testing pile shall be determined according to geologic condition, piles' material and dimension, pile tip type and total engineering piles etc. When the total pile number is less than 500, the testing piles shall not be less than two. The testing pile should increase one if total pile number is increased by 500. When the geologic condition is complex or the types of the piles are multiple, the number may be increased based on the regional experience.
3.1.5 The position of the testing piles shall be determined according to general layout of the engineering, engineering progress, geology, topography, hydrological conditions and design requirements etc. The dimension, buried depth and depth into bearing stratum of testing piles shall be representative.
3.1.6 Bore information shall be provided with within range of 3~10m from the testing pile; the bore bottom elevation shall be lower than pile tip elevation and difference of elevation between the pile tip and bore bottom shall be valued according to the following requirements.
3.1.6.1 For friction pile, common cohesive soil should take 5~8m; old cohesive soil, medium-density and dense sand soil should take 3~5m; rubble soil should take 2m. The difference of elevation between the pile tip of testing pile and bore bottom should not be less than 3~5 times of pile diameter or pile width.
3.1.6.2 Point bearing pile should not be less than 3~5 times of pile diameter or pile width.
3.1.7 Axial compression static load testing should adopt anchor pile method. When reactive force of anchor pile is insufficient, superpose partial lastage. If conditions permit, other load modes may also be adopted for static load test.
3.1.8 The anchor pile shall be arranged by taking testing pile as central symmetry. The center distance of testing pile and anchor pile and reference pile shall not be less than four times of pile diameter or pile width and shall not be less than 2m; the center distance of reference pile and anchor pile shall not be less than 3 times of pile diameter or pile width. For testing pile of major diameter entering into good bearing stratum and pile diameter larger than or equal to 1.2m, the center distance from it to anchor pile and reference pile shall not be less than 3 times of pile diameter.
3.1.9 For the interval time when the testing pile is sunk to load, the cohesive soil shall not be less than 14d; sandy soil shall not be less than 3d; friction pile in sludge or muddy soil shall not be less than 25d; water flush pile sinking shall not be less than 28d. The concrete strength grade of bored concrete pile shall reach the design requirements. Where the compression testing needs to be carried out again for the testing pile, the interval time shall exceed 3d.
3.1.10 Pile body intensity and buckling stability of testing pile shall be checked according to estimated maximum testing load.
3.1.11 Anchor pile shall be subjected to checking of pulling capacity.
3.1.12 Firm testing pile platform shall be erected for static load testing in the waters. The platform shall not be connected with testing pile or reference pile and its elevation shall consider the influence of water level and wind wave etc.
The platform shall be provided with necessary barrier, pedestrians ladder stand, safety mark, signal lamp and survival equipment etc. as well as such equipments on communication and traffic.
3.1.13 The testing shall not be carried out under such conditions as wind, wave etc. and severe hydrological conditions.
3.1.14 During the test, piling operation shall not be carried out within 50m from testing pile, nor all kinds of vibration effect and impact of ship to testing pile platform.
3.1.15 Up-pull volume shall be monitored during the testing and controlled in the allowable range of the design.
