Rehabilitation and upgrading of a zoned fill dike

摘要

The rehabilitation of a zoned fill dike is presented. The dike drawings showed that it is a zoned fill type having a sandy loam core with a filter at the downstream toe and sandstone upstream shoulder. More than two decades after construction, the upstream slope of the dike was submerged by water for the first time. Field observations showed the presence of some cracks at the crest and upstream and downstream slopes and no seepage was observed. Further investigation of the soil of the upstream shoulder showed that it is cemented loamy sand and not sandstone as shown in the drawings. After submergence, the soil of the upstream shoulder lost its cementation. Consequently, two stabilization measures were carried out. The first one was an urgent measure to prevent any further deterioration while the second one was a permanent protection of the dike. The urgent measure consisted of quickly constructing a stabilizing mass of graded sandstone resting on a suitable aggregate filter to support the downstream slope. The second stabilization measure was to place a prism of loamy sand as an extension of the upstream slope covered by three graded filters. Blocks of sound granite mother rock were placed above the upstream surface to protect it against wave and surge effects.