This paper describes with experimental study on in-situ test and thermal stress analysis of cast-in-place pile using high-strength concrete. This investigation led to the following conclusions. 1) a belled pile with a maximum width of 6.7m was carried out, and no cracks occurred in the pile body. 2) From the results of the thermal stress analysis, temperature difference between center and outer circumference of the pile can be suppressed to be smaller in the ground than in the air, because of the heat preservation effect. For this reason, it was found that thermal cracking is unlikely to occur in the ground.
