Which method is typically used to improve high-water-content soils for compaction?

Improving high-water-content soils is crucial for achieving effective compaction, as excessive moisture can hinder the soil's ability to compact properly. The method of scarification and drying is particularly effective in such situations. This process involves breaking up the soil structure through mechanical means, which increases its surface area and allows for quicker evaporation of water. By facilitating the drying process, scarification makes the soil more amenable to compaction as it reaches an optimal moisture content where particles can effectively interlock and stabilize.

In contrast, the other methods may not effectively address the specific challenges posed by high-water-content soils. Tamping may help compact soils with lower moisture levels but is less effective when there is excessive water because the soil particles remain too saturated to bond effectively. Vibration can sometimes help with compaction, but in high-water-content scenarios, it may lead to further displacement of water without improving soil stability. Water addition, on the other hand, is counterproductive in this context since it can exacerbate the issue of excess moisture, making the soil even less suitable for compaction. Thus, scarification and drying stand out as the most appropriate method for improving high-water-content soils.