Abstract: Field tests are carried out on a group of piles in the same site with the same type. Static loading <>Q – <> s curves obtained from piles before and after an interval of 40 days are compared and analyzed. It is found that the bearing capacity of reinforced concrete piles with the manual digging holes does not increase with the time, i.e., no time effect exists. Twice static loading tests are carried out on the same belled short pile. It is found that the bearing capacity increases because of the compaction of soil on the lateral surface and the bottom of the pile. There is time effect on the same pile before and after certain time interval. The longer the interval is, the more the bearing capacity increases.