Optimization of Remedial Measures for Mitigation of Foundation Seepage in Earth Dam—A Case Study

Analysis by numerical modeling software PLAXIS 2D is carried out for the earth dam of Kurha-Vadhodha Islampur sinchan yojana, Maharashtra, India to optimize seepage remedial measures. Depending on the dam cross-sections and foundation stratification, four cases (A, B, C, and D) are analyzed. Results of analyses indicate that for design dam cross-sections, major seepage is occurring through dam foundation with total discharge quantities of 0.7102, 0.7738, 0.2699, and 0.7169 m3/day/m, respectively. As these values are more than the permissible limit, seepage mitigation measures are required to be adopted at site. To determine the most effective remedial measure, analyses are conducted with: (i) rock grouting, (ii) cutoff wall below CoT, and (iii) upstream horizontal blanket in combination with a 6 m deep cutoff wall. Trials are conducted with different depths of cutoff wall and different lengths of horizontal blanket for optimization. For each trial, efficacy is determined by comparing discharge quantity with the permissible limits. Results indicate that seepage discharge quantities with cutoff wall of depth 35 m, 30 m, 5 m and 15 m for cases A, B, C, and D are 0.1936, 0.1892, 0.1602 and 0.1751 m3/day/m, respectively; which are less than the upper permissible limit. Hence, cutoff wall of above depths is recommended as the most effective seepage remedial measure for the earth dam of Kurha-Vadhodha Islampur sinchan yojana.