The minimum number of piles required for static load test

[wangqian]

Hello every one，Did you know where I can find requirement about the minimum number or scale of piles required for static load test for a project？

 

[EireChch]

There is no real minimum etc. Its all about the reaction you need. If you get it from 2 piles, no reason you cant use just 2.

 

[HTURKAK]

Eurocode 7 is law resource so access is free and i have copy and pasted the relevant clause to get some insight ;


7.5 Pile load tests
7.5.1 General (1)P Pile load tests shall be carried out in the following situations: — when using a type of pile or installation method for which there is no comparable experience; — when the piles have not been tested under comparable soil and loading conditions; — when the piles will be subject to loading for which theory and experience do not provide sufficient confidence in the design. The pile testing procedure shall then provide loading similar to the anticipated loading; — when observations during the process of installation indicate pile behaviour that deviates strongly and unfavourably from the behaviour anticipated on the basis of the site investigation or experience, and when additional ground investigations do not clarify the reasons for this deviation. (2) Pile load tests may be used to: — assess the suitability of the construction method; — determine the response of a representative pile and the surrounding ground to load, both in terms of settlement and limit load; — to allow judgement of the overall pile foundation. (3) Where load tests are not practical due to difficulties in modelling the variation in the load (e.g. cyclic loading) very cautious design values for the material properties should be used. (4)P If one pile load test is carried out, it shall normally be located where the most adverse ground conditions are believed to occur. If this is not possible, an allowance shall be made when deriving the characteristic value of the compressive resistance. (5)P If load tests are carried out on two or more test piles, the test locations shall be representative of the site of the pile foundation and one of the test piles shall be located where the most adverse ground conditions are believed to occur.

I remember one of the standard ;
-at least one pile for each case and each different diameter ;
-two piles after 200 total no. piles ,
- at least 0.5% of the total number of piles if the no of piles more than 500.