It also proposes an empirical formula for computing the relative hydraulic head at downstream of the grout curtain for infinitely deep homogeneous foundation.

To control foundation seepage and exit gradient, a plastic concrete cut-off wall, a grout curtain, and a set of downstream pressure relief Wells are incorporated in the design.

In order to appraise the quality testing of grout curtain, digital borehole camera technology is applied to three boreholes of the grouting gallery no. 3 in Xiaolangdi Water Control Project.