云南漫湾水电站工程大坝变形与扬压力监测成果分析

Analyses of observed deformation and upift of Manwan dam

本报告对漫湾水电站工程大坝的变形、扬压力、绕坝渗流等监测资料进行了分析，通过分析认为坝基和坝体水平位移较小，分别向下游位移１．４４ｍｍ和７．９１ｍｍ；坝基实测扬压力比设计扬压力小，７号、１２号、１６号坝段实测扬压力分别为设计扬压力的４４．２％、６４．２％和５９．２％，有利于抗滑稳定，增加大坝安全度。坝基排水幕处渗压系数均比设计值０．２小，７号、１２号、１６号坝段排水处的渗压系数分别为０、－０．３３、０．０７～０．１４，说明大坝防渗帷幕灌浆效果良好。绕坝渗流除两岸坝头帷幕前的测压管接近库水位外，其它测点水位均比库水位低得多，说明资料正常。通过分析认为，大坝自１９９３年３月２７日下闸蓄水以来，工作性态正常，未见有异常现象。

The observed results of deformation, uplift pressure and by-pass seepage of Manwan dam in Yunnan Province are analysed in this paper. The analyses show that the horizontal displacemets of foundation and dam are comparatively small, with 1.44 mm of foundation displacement and 7.91 mm of dam crest one downstream; the values of uplift pressure on the interface between dam and foundation are less than the design ones, with observed values at dam block 7, 12 and 16 amounting to 44. 2 %, 64. 2%and 59. 2% of respective design values respectively. Observed values of coefficient of seepage pressure reduction near the drainage screen at dam block 7, 12 and 16 are less than 0. 2 of design value, indicating the seepage proof curtain of good quality. For by-pass seepage, the relevant piezometric levels are much lower than the reservoir level, except the piezmetric tubes in front of the seepage proof curtain near both dam ends, in which the piezmetric levels are close to the reservoir level. From analyses of observed data, it may be considered that the behaviour of this dam has been normal without unusual indication observed, since the reservoir impounding on March 27, 1993.