A significant portion of D'Appolonia's practice is related to the planning of cuts and fills and the design of earth slopes or earth retaining structures with mechanical components. We are experienced in planning site grading for highways and other types of developments. Our excavation plans consider the types and quality of soil and rock to be excavated, identify methods for segregating suitable materials for road subgrade construction, designate areas for placing unsuitable materials, and provide plans and specifications for handling and compacting the subgrade materials. We are experts in the design of earth slopes and rock cuts, including development of specifications for blasting and blast monitoring. We frequently incorporate technologies such as anchored retaining walls, soil nails, micropiles, and various mechanically stabilized earth (MSE) configurations in our designs.

Loess bluff along the Mississippi River stabilized through the use of soil nails.

Some typical D'Appolonia projects involving remediation of slope failures, design of supports for roadways and other aspects of roadway design and stabilization are provided in the following:


Retaining Walls and Slope Stabilization at Lewistown Narrows

D'Appolonia was retained to evaluate special bridge foundations, earth retaining structures, and soil-structure interaction systems associated with highway construction for the Lewistown Narrows project. D'Appolonia supported the engineering design team in developing a design philosophy and analysis procedures for geotechnical and structural design of micropile, drilled-shaft and driven-pile foundations to improve the stability of talus slopes to acceptable levels of global stability and to support retaining walls used for grade separation between opposing highway lanes.

Blue Trail Landslide Stabilization on U.S. Route 26/89 in Wyoming

D’Appolonia developed a repair scheme incorporating a three-tiered configuration of reticulated micropile walls to stabilize a landslide that had been a major maintenance problem for the Wyoming DOT. For its work on the project, D'Appolonia was awarded the 1998 Grand Award for Excellence in Engineering Design by the American Consulting Engineers Council.

Excavation Support for Railway Bridge and Highway Underpass

A roadway improvement project involving the construction of a new railway bridge and highway underpass was undertaken by PennDOT. D’Appolonia developed a more constructible alternative design that satisfied the stringent construction criteria of PennDOT and the railroad. The alternative excavation support system designed by D'Appolonia was successfully implemented and exceeded project performance requirements.

Innovative Stabilization of Loess Bluff along the Mississippi River

D’Appolonia was lead designer for a design/build team selected by the U.S. Army Corps of Engineers, Vicksburg District (COE) to design a stabilization plan for 200-foot-high loess bluffs above the Mississippi River in Natchez, Mississippi.

Bluff Stabilization along the Mississippi River near Hickman, Kentucky

As part of an open-end contract for the US Army Corps of Engineers, Memphis District, D'Appolonia was retained to conduct preliminary analyses of suitable alternatives for stabilizing a 500-foot-long section of 100-foot-high loess bluff and to prepare final design drawings and specifications for the selected alternative.

Open-End Geotechnical Engineering Services Contract

D'Appolonia provided civil and geotechnical consulting engineering services to Allegheny County, Pennsylvania on a variety of projects involving geotechnical engineering for roadways including subsurface explorations, evaluation of slope instability problems, design of earth-retaining structures, and roadway design.

Evaluation of Changed Conditions and Embankment Redesign

D'Appolonia analyzed planned designs for roadway support involving the construction of embankments ranging up to 340 feet high. Our analyses indicated that the planned slope configurations would not provide adequate facotrs of safety. Modifications to the remedial designs were successfully implemented based upon our evaluation.