坝后背管运行期温度应力分析

Temperature stress analysis on penstocks on downstream surface of dam during operation

采用ANSYS软件,针对黄河李家峡水电站坝后背管,计算分析运行期冬、夏2个特殊阶段管壁内外温降、温升作用下的温度场和温度应力,以及温度场和内水压力叠加产生的应力。夏季管腰环向温度应力反映出从内壁到外壁、由受拉到受压的变化规律;冬季管腰环向温度应力反映出从内壁到外壁、由受压到受拉的变化规律。冬夏不同的温度梯度产生的拉压应力变化使背管混凝土裂缝处于闭合、张开的交替状态,会使裂缝的分布规律与纯粹的简支梁受弯构件的裂缝分布有所不同。

By using the ANSYS software,the temperature field stress and the stress resulted from superposition of temperature field and internal water pressure of penstocks of the Lijiaxia hydropower station in winter and summer operation are analyzed. During summer,the temperature hoopstress in the middle section of penstocks reflects the variation law of tension in internal wall to compression in external wall; While during winter,the temperature hoopstress in the middle section of penstocks reflects the variation law of compression in internal wall to tension in external wall.The tensile stress variation due to the different temperature gradient in winter and summer results in the concrete cracks in an alternative status of opening and closing,amd makes the distribution law of cracks different from that of cracks in freely supported beam member in bending.