Wick DrainsHelping soft soils settleWhat are Wick Drains?
How are Wick Drains Installed?Wick drains are installed with specialized equipment, called stitchers. The stitchers, which are mounted on either backhoes or cranes, consist of a vertical mast housing a special installation ![]() What are Typical Applications?Wick drain projects have included dams, large storage areas, highway embankments, sedimentation ponds, tanks, bridge abutments, buildings, and airport runways. The most common application of wick drains is for accelerating the settlement rate of compressible soils. At some sites, the primary purpose of wick drains is to increase the shear strength of underlying soft soils. As soil consolidates, the shear strength increases due to a reduction in the water content. This application is particularly important when high area fills have to be placed over soft soils with low shear strength. Potential instability problems can be overcome by loading the site in stages and allowing the soft soils to gain in strength under each stage before placement of the next stage of fill. Wick drains have also been used in conjunction with other ground improvement techniques, such as dynamic compaction, to allow rapid dissipation of excess pore pressures. How are Wick Drains Designed?The rate of soil consolidation or settlement is controlled by how rapidly the pore water can escape from the soil. The controlling variables are the spacing between the wick drains and the permeability of the soil. The amount of consolidation is independent of whether wick drains are present and is determined by the soil compressibility and the weight of the fill above the wicks. By developing a set of design curves of drain spacing, fill height, and consolidation time, the most economical drain spacing and height of fill can be selected to achieve a given degree of consolidation in a specified time period. |