某碾压混凝土坝7号坝段异常水平位移原因分析

Cause analysis of abnormal horizontal displacement of section 7 of a RCC dam

以某碾压混凝土坝7号坝段异常变形作为分析实例,根据坝体实测温度场,采用有限元法计算坝体温度变化对大坝水平位移的影响,采用混合模型法反演坝体弹性模量。分析结果表明,水位变化对7号坝段水平位移影响幅度在合理范围内,由于坝体温度场受气温影响小,温度分量占比较小,导致库水位分量占比相对较大,因此水平位移表现为与库水位相关性明显;考虑坝体温降及测值突变影响,坝体不存在明显趋势性位移;坝基趋势性位移主要发生在蓄水过程中,正常运行以来坝基向下游变形仅1 mm左右,不影响大坝安全运行。该结论为大坝安全性评价提供了可靠依据。

The abnormal horizontal displacement of section 7 of a RCC dam is analyzed in this paper.Based on the measured temperature field of dam body, the influence of the dam's temperature variationon horizontal displacement is calculated by finite element method, and the elastic modulus of dam bodyis retrieved by mixed model method. The results show that the influence of water level variation on hori-zontal displacement of section 7 is within a reasonable range. As the temperature field of dam is less af-fected by temperature, the influence of reservoir water level is relatively large. Therefore, horizontal dis-placement shows obvious correlation with reservoir water level. Considering the temperature drop of damand the abrupt change of measuring values, there is no obvious trend displacement in the dam body. Thetrend displacement of dam foundation mainly occursed during storage. Since the normal operation, thedownstream deformation of dam foundation is only about 1 mm, which does not affect the dam safety op-eration. The results of the study provide a reliable basis for dam safety evaluation.