三峡工程左岸电站采用保压方式浇筑蜗壳外围混凝土。为研究钢蜗壳与外围二期混凝土交界面的传力以及可能存在的间隙，采用三维非线性有限元法，对左岸10#机组进行模拟施工过程的温度场与温度应力仿真计算，给出了在不同运行情况及不同季节时二者之间传力及间隙的变化。计算值与现场观测值有很好的一致性。

The surrounding concrete of steel spiral case in the power station of Three Gorges Project(TGP) is constructed by means of keeping aspecific level of internal pressure during construction. For analyzing the contact behavior of the interface between the steel spiral case and its surrounding concrete，the numerical simulations of the construction process according to the actual construction procedure are carried out with 3-D FEM．The variation of the gap and the interaction force between the steel spiral case and its surrounding concrete in different operation stages and different seasons are put forward. By comparing the? computed results with the prototype safety monitored data during and after the construction of surrounding concrete, it shows that they are in good agreement. The method and the program are proved to be feasible.