渗流反演分析在工程设计中的应用

 马来西亚明光水库大坝为风化花岗岩残积土基础，勘探结果表明，坝基渗透性指标离散性大，得出坝基土渗透性较小、不予进行防渗处理的结论。然而，在水库运用过程中，出现渗漏现象。工程扩建加高，仅依据现场试验结果，对地基渗透情况作出评价更为困难。根据实测资料，进行反演分析，推求坝基、坝体的渗透系数。通过反演分析，得出与观测结果基本一致的坝体、坝基渗透性指标，成为工程设计的主要依据，并指出勘探成果发生离散的原因。运用反演分析得到的参数，对扩建加高后的大坝渗流量及坝基渗透稳定性进行预测和评价，得出大坝渗漏量大、坝基渗透稳定不满足要求、需要进行防渗处理的结论，并针对该工程的实际情况提出防渗处理方案。

APPLICATION OF SEEPAGE BACK ANALYSIS TO ENGINEERING DESIGN

Mengkuang Dam in Malaysia has a foundation filled with residual soil of weathered granite. The exploration indicates that the permeability index for dam foundation has great dispersion，drawing the conclusion that the dam foundation soil has small permeability and anti-seepage treatment is not required. However，seepage appears during the reservoir operation. After the project upgrading，it is difficult to make assessment on foundation permeability only based on the results from field test. In this article，inversion analysis is conducted to ascertain the permeability coefficient for dam body and foundation based on the measured data. Through the analysis，permeability indices for dam body and foundation conforming to the observation are obtained，providing main basis for engineering design and showing the reason for dispersion of exploration result. Parameters from inversion analysis are used for permeability prediction and assessment on dam seepage quantity and dam foundation seepage stability after upgrading，drawing the conclusion that the dam seepage quantity after upgrading is large. The requirement for dam foundation seepage stability can not be satisfied and anti-seepage treatment is required. With respect to the real situation of the project，the anti-seepage scheme is proposed.