The construction and design of flood protection embankment levees within coastal areas has become a focal point for infrastructure management. The levees are usually constructed over soils with very poor bearing capacity due to their proximity to flood plains. The foundation soils create issues with long-term settlement, changing the protection height and creating the need to periodically build the levee back to the design height. In order to reduce settlements and the maintenance required to preserve design height protection, DSM is needed for proper long term load transfer.
Also, dam sites with slightly cohesive soils and fine sands in the foundation are typically vulnerable to significant loss of strength by liquefaction during a potential strong earthquake. DSM has been recommended to remediate a potentially weak foundation and thereby improve the seismic stability of an earth embankment dam. With the proper use of reinforcement, these applications can become even more efficient in time and cost vs. unreinforced.
Raito has decades of successful experience protecting some of the nation’s most challenging levee seepage control, chemical containment, and groundwater cut-off wall projects. Our products have been utilized in numerous U.S. remediation projects, including Sacramento River Levee Flood Protection and Mississippi River Hurricane Flood Wall projects. Cutoff walls are used to exclude groundwater from an excavation, to minimize the requirement for dewatering pumping. Typically, the method involves installing a very low permeability physical cut-off wall or barrier around the perimeter of the excavation to prevent groundwater from entering the working area. Most commonly, the cut-off is vertical and ideally penetrates down to a very low permeability stratum (such as a clay or unfractured bedrock) that forms a basal seal for the excavation.
RSW method mixes in-situ soils with cement grout or other reagents slurries using a multiple shaft auger to produce continuous subsurface soil-cement walls for excavation support, groundwater or underground pollutants control, or ground reinforcement. The soil-cement is usually reinforced with steel H-piles when used for excavation support along with groundwater control.
Jet Grouting is a technique of mixing in-situ soil with the energy of ultra-high pressure jet of slurry. A small-diameter rod drills down to the improvement bottom. Then the rod, while being withdrawn, jets the cement-base slurry and air to produce an improved column. Jet Grouting enables improvement closely contacted to or, in some cases, encompassing existing underground structures without causing damage to them.
The Sacramento River Flood Control System includes dams and reservoirs, levees, weirs, bypasses, and other features built over the last 150 years. Approx. 980 mi of levees in this complex system protect urban and rural areas within the Sacramento River Watershed of 27,100 mi2 from frequent flooding.
In 2005, Hurricane Katrina and Rita made landfall, causing major damage in southwest Louisiana and the Louisiana-Texas state line. DSM was performed for the WBV Hurricane Protection Project. This project included reinforcement of flood walls for higher water events in the Westwego to Harvey area.