Soil Improvement
Many Dams built in the first part of the 20th century have been found to be lacking in terms of stability for the current design levels for seismic loads and so typically compaction of the clean (possibly) alluvial sands is needed for liquefaction mitigation. However, sometimes the dams have been formed from old mine tailings and as such the dam structure itself (if not the core, then the surrounds) may also need treatment. In these situations, treatment outside the footprint of dam maybe possible, but for treatment under the dam, then grouting or soil mixing maybe the most beneficial step.
At Bauer we have the tools to assess the needs, and the machines and techniques to provide the solution for the rehabilitation of the dam.
For newly built dams, or even the treatment of tailings, then a similar approach follows to that described previously. What are the targets or needs of the client/consultant in terms of slope stability (for dynamic and static cases), does the existing ground need to be treated to allow the construction of the dam (for settlement control, or liquefaction or slope stability)? Does the available material (sand, clays, tailings, silts) need treatment (by soil mixing or other mechanical treatment methods)? Bauer can offer the use of vibrocom- paction or dynamic compaction for the treatment of sands or silty sands for liquefaction and settlement control, with these being effective to 50 m or 15 m respectively, in case of more silts or fine contents then techniques such as soil mixing, full displacement columns or stone columns may be used to provide not only settlement control, but slope stability and liquefaction mitigation methods.
