Abstract:
This presentation describes the design, analysis, and construction of a permanent anchored secant pile wall installed for the Virginia War Memorial Expansion in Richmond, Virginia. The excavation extended 20 below grade adjacent to a museum structure, with movement tolerances limited to ½ inch vertical and ¼ inch horizontal displacement.
Subsurface conditions included 15 to 30 feet of highly variable fill over alluvial clays, with groundwater present near the excavation subgrade. Due to soft, water-bearing soils and strict alignment requirements, the plan included 35-inch sectional casing to construct interlocking primary and secondary piles spaced at 5 feet on center. Once excavation progressed, 75-foot-long pressure-grouted anchors were installed through primary piles and tested to 119 kips.
Plain strain finite element modeling was performed to estimate wall deformations during staged excavation. Predicted maximum horizontal movement was approximately 1/4 inch. Inclinometer monitoring recorded actual maximum movements of less than 1/10 inch.
The case history highlights constructability considerations, tolerance control, anchor integration, and the value of calibrating numerical models with field instrumentation for permanent secant pile wall performance adjacent to sensitive structures.
NOTE THAT WE THOUGHT THIS WOULD BE A GOOD PROJECT FOR A 20 TO 25 MINUTE REGULAR PRESENTATION.