堆石料残余体应变对计算面板堆石坝永久变形的影响

混凝土面板堆石坝地震永久变形的预测非常重要。根据它可直接判断大坝的安全，并为抗震预留坝高提供依据。一个时期以来，同时计入堆石料残余体应变对面板坝永久变形计算有多大影响存有争议。采用饱和排水动三轴试验方法得到的动应力～残余应变关系计算坝体的永久变形，所得数值一般偏大。而风干堆石料在排气状态下的三轴试验，目前只能考虑残余剪应变。本文利用前人对不同试验方法得到的动应力～残余应变关系进行面板堆石坝地震永久变形计算做了比较，结果表明：由于坝体运用期间有部分堆石浸水，故其永久变形的计算对浸水线以上坝体采用风干料排气试验结果只考虑残余剪应变，浸水线以下坝体采用饱和料排水试验结果同时计入残余体应变和残余剪应变，比整个坝体采用饱和料排水试验结果同时计入残余体应变和残余剪应变为合适。

Influence of Residual Volumetric Strain of Rockfill Material on Calculated Permanent Deformation of Concrete Faced Rockfill Dams

Prediction of earthquake induced permanent deformation of concrete faced rockfill dams is of great importance. This study suggests an idea for evaluation of the surplus heightening of the dam reserved for earthquake protection. For a long time, there exists different point of view concerning how much the influence of residual volumetric strain of rockfill material on the calculated permanent deformation of concrete faced rockfill dams. The relationship between dynamic stress and residual strain obtained from saturation drainage triaxial test gives some larger results. For air dry rockfill material, only residual shear strain can be obtained by triaxial test under the condition that the air contained in the specimen be removed. This paper compares the computed permanent deformation performances of concrete faced rockfill dams by using different relationship between dynamic stress and residual strain, which are obtained from different experimental methods. In fact, during the operation period, part of the rock mass is situated under the water level. The result shows that, for computation of permanent deformation, it is more reasonable to use the residual strain of dry material for the part of the rock mass located at the level higher than the drainage water level and to use the residual strain of saturated material for the part of the rock mass located at the level lower than the drainage water level.