The early hydration of concrete will release a lot of heat

which will cause the change of temperature and stress of pile body

thus affecting the bearing capacity of pile-cap.Through field tests

the influence of hydration heat of bored pile-cap concrete on pile body and soil around pile foundation is studied.The variation of temperature of the pile foundation and the soil around pile along depth and with time

and the stress history of pile foundation are measured and analyzed.The results show that the temperature at all depths of the pile reaches its maximum value at day0.7 after the completion of concrete pouring.At day 21.4

the temperature of the pile is basically stable.The law of temperature variation with time can be divided into four stages:rapid rise

rapid decline

gentle decrease and basic stability.The hydration heat effect of cap concrete has only a certain effect on the temperature of shallow soil around pile foundation.When the depth is more than 3 m

the effect of hydration heat on the temperature of soil can be neglected.The confinement stress of pile foundation first increases rapidly

then decreases slowly and finally tends to be stable.The maximum confinement stress value is very close to the axial tensile strength of concrete.