RCC拱坝的封拱温度与温度荷载研究

Grouting temperature and thermal load of RCC arch dam

在对RCC拱坝封拱温度与温度荷载特点分析的基础上,用4座不同坝高的RCC拱坝分别以坝体多年平均温度和由仿真分析计算得到的蓄水时的实际温度作为温度荷载的计算起点,用有限元等效应力法计算不同坝高的坝体应力,根据计算结果讨论不同坝高时RCC拱坝的封拱温度与温度荷载。计算表明,以多年平均温度作为封拱温度计算温度荷载与仿真方法计算的温度荷载的差距随着坝高的增大而增大。对于100m以上的拱坝应该用仿真分析的方法研究温度荷载,以确定真实的封拱温度;不进行二期水冷和封拱灌浆时,对于100m以上的高拱坝,要进行充分论证,一般坝踵可能会出现较大拉应力而引起坝踵开裂;对于RCC高拱坝应采用冷却水管和分缝相结合的方式,在蓄水前通过二期水冷使坝体温度下降到设计封拱温度后进行封拱灌浆,以减小运行期的温度荷载。

The finite element eqaivalent stress method was applied to calculate the stresses of 4 RCC arch dams to analyze the effect of arch sealing temperature on thermal load at different dam heights.The perennial average temperature of the dam and the temperature during impounding obtained from simulation analysis were taken as the initial conditions to carry out the calculation respectively.The following conclusions are obtained：（1）The difference between temperature load calculated by taking perennial average temperature as the arch sealing temperature and temperature load calculated by simulating method will increase with the increase of dam height.For arch dams which higher than 100m,simulating analysis method should be used to study the temperature load to determine the real arch sealing temperature.（2）If second phase water cooling and arch sealing and grouting are not carried out,adequate argumentation should be conducted.Generally,large tensile stress will appear on the dam heel,which will induce cracking of the dam heel.（3）Water cooling pipe and joint setting measures should be jointly adopted to RCC high arch dam.To reduce the temperature load in operation,by using second phase water cooling to lower the dam temperature to designed arch sealing temperature before impounding,and then conduct arch sealing and grouting.