
锦屏一级水电站边坡变形对拱坝影响分析
邱茂星, 位伟
锦屏一级水电站边坡变形对拱坝影响分析
An Analysis of the Influence of Slope Deformation on Arch Dam of Jinping I Hydropower Station
库岸边坡在长期库水涨落循环作用下容易发生变形,进而可能引起大坝的开裂甚至破坏,因此边坡变形对拱坝安全有重要影响。锦屏一级水电站经历了六次库水涨落循环,依据监测资料,对边坡变形进行流变反演计算,并通过正向计算预测了边坡的长期变形情况,研究了在上游正常蓄水位1 880 m和死水位1 800 m两种水位条件下,及不同边坡变形情况下拱坝的变形和应力分布情况。结果表明,2012年蓄水后至2020年7月,拱坝整体变形较小,右岸1 800 m高程以上坝肩拉应力区明显减小,拱坝受力状态有局部改善;2020年7月至边坡长期变形收敛阶段,拱肩槽边坡变形较小,左拱端下游侧横河向变形增量小于1.2 mm,拱坝拉应力量值和分布范围改变不明显。因此,水库蓄水后至边坡长期变形收敛阶段,拱坝应力应变量值处于合理区间,锦屏一级高拱坝应力应变总体处于弹性工作的安全运行状态。
The bank slope of reservoir is prone to deformation under long-term circulation of reservoir water fluctuation, which may lead to the cracking and even failure of the dam. Therefore, slope deformation has important influence on the safety of the arch dam. Jinping I Hydropower Station has experienced six fluctuation cycles of the reservoir water. The rheological inversion calculation of the slope deformation is conducted based on the monitoring data, and the long-term deformation of the slope is predicted. In development, the deformation and stress conditions of the arch dam under the conditions of normal water level of 1 880 m and dead water level of 1 800 m and different slope deformation are studied. The results show that the overall deformation of the arch dam was minor from the impoundment to July 2020. Furthermore, it is revealed that the tensile stress area of the abutment above the elevation of 1 800 m of the right bank decreased significantly, which means that the stress state of the arch dam has been partially improved. On the other hand, during the stage from July 2020 to the convergence of the slope after the long-term deformation, the deformation of the abutment groove slope will be small, the transverse deformation increment of downstream side of the left arch end will be less than 1.2 mm, and the magnitude and distribution range of the tensile stress of the arch dam will not change obviously. Therefore, from the reservoir impoundment to the convergence of the slope after the long term deformation, the stress and strain values of the arch dam are in a reasonable range, and the stress and strain of Jinping I high arch dam are generally in the safe operation state of elastic work.
高拱坝 / 边坡变形 / 应力 / 水库蓄水 / 锦屏一级水电站 {{custom_keyword}} /
high arch dam / slope deformation / stress / reservoir impoundment / Jinping I Hydropower Station {{custom_keyword}} /
表1 岩体力学参数Tab.1 Mechanical parameters of rock mass |
材料分类 | E /GPa | ν | γ /(kN·m-3) |
---|---|---|---|
大坝混凝土 | 24.000 | 0.167 | 24.0 |
混凝土垫座 | 21.000 | 0.167 | 24.0 |
II类岩石 | 26.000 | 0.250 | 28.0 |
III1类岩石 | 11.500 | 0.250 | 28.0 |
III2类岩石 | 6.500 | 0.300 | 28.0 |
IV1类岩石 | 3.000 | 0.350 | 27.5 |
IV2类岩石 | 2.000 | 0.350 | 27.5 |
V1类岩体 | 0.375 | 0.350 | 27.5 |
f5、f8、f42-9 | 0.375 | 0.350 | 26.0 |
X (El.1 680 m以上) | 2.000 | 0.350 | 27.5 |
X (El.1 680 m以下) | 6.500 | 0.300 | 28.0 |
表2 荷载组合工况Tab.2 Load combination conditions |
工况 | 荷载组合 | ||||
---|---|---|---|---|---|
工况1 | 无边坡变形 | 上游正常蓄水位1 880 m | 上游泥沙压力 | 坝体自重 | 下游水位1 640 m |
工况2 | 边坡当前变形 | ||||
工况3 | 边坡长期变形 | ||||
工况4 | 无边坡变形 | 上游 死水位 1 800 m | |||
工况5 | 边坡当前变形 | ||||
工况6 | 边坡长期变形 |
图3 2013年6月-2020年7月边坡外观测点水平位移矢量监测值及参与反演的外观测点Fig.3 The monitored values of horizontal displacement vectors of the outer observation points of the slope from June 2013 to July 2020 and the outer observation points participating in the inversion |
表3 流变参数反演结果Tab.3 Rheological parameter inversion results |
岩体类别 | 弹性模量/GPa | 黏弹性模量/GPa | 黏滞系数/(亿GPa·s) |
---|---|---|---|
III1类 | 8.75 | 10.2 | 10.0 |
III2类 | 4.73 | 5.53 | 7.0 |
IV1类 | 2.08 | 3.47 | 4.0 |
IV2类 | 0.82 | 0.79 | 1.0 |
f5、f8、X、f42-9、SL42-1 | 0.23 | 0.4 | 0.8 |
图5 外观测点正向计算横河向位移随时间变化曲线Fig.5 Forward calculation of transverse displacement curve with time at outer observation points |
图6 2020年7月左岸边坡拱肩槽横河向位移云图Fig.6 Transverse river displacement of arched shoulder groove of the left bank slope as of July 2020 |
表4 拱坝下游坝面最大位移及出现位置 (mm)Tab.4 Maximum displacement and position of downstream dam surface of arch dam |
工况 | 左拱端 | 拱冠梁 | 右拱端 | |||
---|---|---|---|---|---|---|
顺河向 | 横河向 | 顺河向 | 横河向 | 顺河向 | 横河向 | |
工况1 | 26.7 σ1 710 m | 8.5 σ1 710 m | 78.2 σ1 830 m | -3.2 σ1 885 m | 17.7 σ1 740 m | -4.7 σ1 770 m |
工况2 | 29.6 σ1 710 m | 8.1 σ1 710 m | 79.8 σ1 800 m | -4.9 σ1 885 m | 19.0 σ1 740 m | -4.6 σ1 770 m |
工况3 | 29.7 σ1 710 m | 8.2 σ1 710 m | 79.8 σ1 800 m | -4.9 σ1 885 m | 19.0 σ1 740 m | -4.6 σ1 770 m |
工况4 | 10.8 σ1 680 m | 2.6 σ1 680 m | 15.5 σ1 710 m | 0.7 σ1 885 m | 7.6 σ1 650 m | -0.9 σ1 710 m |
工况5 | 13.5 σ1 680 m | -2.7 σ1 885 m | 26.7 σ1 710 m | 0.8 σ1 885 m | 9.3 σ1 650 m | -0.7 σ1 740 m |
工况6 | 13.6 σ1 680 m | -3.9 σ1 885 m | 29.7 σ1 710 m | 0.9 σ1 650 m | 9.3 σ1 650 m | -0.7 σ1 740 m |
图8 工况1下游坝面位移图(单位:mm)Fig.8 Displacement diagram of downstream dam surface under condition 1 |
图9 工况2下游坝面位移图(单位:mm)Fig.9 Displacement diagram of downstream dam surface under condition 2 |
图11 工况4下游坝面位移云图(单位:mm)Fig.11 Displacement diagram of downstream dam surface under condition 4 |
图12 工况5下游坝面位移云图(单位:mm)Fig.12 Displacement diagram of downstream dam surface under condition 5 |
表5 正常蓄水位1 880 m三种工况下大坝主应力最大值Tab.5 Maximum principal stress of dam under three working conditions of normal water level 1 880 m |
工况 | 位置 | 拉应力 | 压应力 | ||
---|---|---|---|---|---|
值/MPa | 位置 | 值/MPa | 位置 | ||
工况1 | 上游坝面 | 1.67 | σ1 742 m右拱端 | -6.21 | σ1 743 m拱冠梁 |
下游坝面 | 0.33 | σ1 885 m右拱端 | -10.56 | σ1 597 m右拱端 | |
工况2 | 上游坝面 | 1.82 | σ1 592 m右拱端 | -6.56 | σ1 743 m拱冠梁 |
下游坝面 | 0.28 | σ1 885 m右拱端 | -10.79 | σ1 597 m右拱端 | |
工况3 | 上游坝面 | 1.90 | σ1 592 m右拱端 | -6.57 | σ1 743 m拱冠梁 |
下游坝面 | 0.27 | σ1 885 m右拱端 | -10.78 | σ1 597 m右拱端 |
表6 死水位1 800 m三种工况下大坝主应力最大值Tab.6 Maximum principal stress of dam under three working conditions of dead water level 1 800 m |
工况 | 位置 | 拉应力 | 压应力 | ||
---|---|---|---|---|---|
值/MPa | 部位 | 值/MPa | 部位 | ||
工况4 | 上游坝面 | 0.98 | σ1 743 m右拱端 | -13.7 | σ1 580 m左拱端 |
下游坝面 | 0.92 | σ1 885 m拱冠梁 | -8.2 | σ1 597 m右拱端 | |
工况5 | 上游坝面 | 0.89 | σ1 743 m右拱端 | -13.5 | σ1 580 m左拱端 |
下游坝面 | 0.28 | σ1 885 m拱冠梁 | -8.5 | σ1 597 m右拱端 | |
工况6 | 上游坝面 | 0.90 | σ1 743 m右拱端 | -13.4 | σ1 580 m左拱端 |
下游坝面 | 0.28 | σ1 885 m拱冠梁 | -8.5 | σ1 597 m右拱端 |
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