Abstract:

Anti-seepage in thick overburden dam base is one of the key problems for dam construction and dam safty. It has been used in several dam projects that the plastic concrete anti-seepage wall plus grouting curtain regarded as the waterproof system. The anti-seepage wall construction impropriated the time limit for such projects; so, it should be shortened as its possible. To study the optimum depth of anti-seepage wall is needed. An analytical solution for grading downwards the anti-seepage wall is deduced based on the drag index methods. And it is studied in detail that the law of grading downwards the anti-seepage wall varied with its depth increase. The results show that the depth of anti-seepage wall in limited thick overburden is not the deeper the better. By contraries, it was sure that there was an optimal depth, in which grading downwards the anti-seepage wall is the least. The value of the optimal depth is related with the depth of the overburden. In general, when the relative depth ratio between the depth of anti-seepage wall and overburden is about 0.7; grading downwards the anti-seepage wall is at the least.

Key words: thick overburden, dam base, anti-seepage wall, seepage