In the process of operation

the temperature of intermediate joint of power cable is usually higher than that of the cable body

and the steady-state current carrying capacity

which is calculated on such basis that the temperature rise of the cable body is no more than 90 ℃

will cause damage to the intermediate joint. For the direct buried DC cable joint

the accuracy of temperature and current carrying capacity calculation is high by using a three-dimensional model which is constructed by finite element simulation software. In order to simplify the calculation process at the same time

the plane structure of the joint is set up by using the two-dimensional axis symmetric module

which is rotated to form a three-dimensional model of the intermediate joint. The temperature and steady-state current carrying capacity of cable joints and cable body in soil are simulated and calculated. The current carrying capacity

determined by the cable body

will make the conductor temperature of the joints higher than the maximum long-term allowable temperature

which is not favourable to long-term and stable operation of cables. The heat resistance of the soil around the joint is increased by water migration

and the steady-state carrying capacity of the intermediate joint can be increased

to a certain extent

by back-filling sand.