DESIGN OF BRIDGE FOUNDATIONS


Highways typically encounter a wide range of subsurface foundation conditions because of their linear extent and because of the inherent inflexibility of location options once the preferred route has been selected. Thus, conditions that were not originally anticipated may occur in the field and must be dealt with by adjusting the design to accomodate actual conditions. D'Appolonia has designed foundations for a wide range of structures, including both bridge abutments and support piers. We perform explorations and analyses to identify cost-effective options for specific subsurface conditions. We have prepared designs for stabilizing soils to support spread footings, and we routinely design foundations utilizing driven piles, drilled shafts and micropiles where these methodologies are technically and economically attractive.



D'Appolonia developed designs for stabilizing displaced piers and supporting abutments for dual highway bridges.



Some representative projects involving the design of bridge pier and abutment foundations are provided in the following:


EXAMPLE PROJECTS


Analysis of Tioga River Bridge Abutment Settlement

D’Appolonia performed forensic engineering evaluations and analyses to assess greater than expected settlement of the northbound abutment at the south end of the Tioga River Bridge in Tioga County, Pennsylvania. Stability analyses for the bridge abutment were performed using the SLIDE computer program, and deformation analyses were performed using the two-dimensional PLAXIS stress-deformation program.


Evaluation of Distressed Piers at 14th Street Bridge in Washington, DC

D’Appolonia provided geotechnical engineering services for a geotechnical and structural evaluation of unusual cracking in masonry-faced, pile-supported, reinforced-concrete piers supporting the 14th Street Bridge over the Potomac River in Washington, D.C.


Value Engineered Micropile Foundation Alternative

D’Appolonia teamed with a micropile contractor to perform a value-engineered foundation study for two of the five piers for the Gene Hartzell Memorial Bridge. Our design involved replacement of 48-inch-diameter drilled shafts with a micropile alternative. Our designs were implemented by PennDOT resulting in an estimated savings of $200,000 and three months of construction time.


Remediation of Bridge Distress Caused by Slope Movement

D’Appolonia planned and carried out a site subsurface exploration program and performed a value engineering study to develop an economical alternative for stabilizing piers associated with bridges carrying Interstate 80 over Canoe Creek near Knox, Pennsylvania. The piers were stabilized by reconstruction of an adjacent slope, and new abutments were supported on spread footings, resulting in an approximately $100,000 savings over the original repair concept.


Value Engineering Study for Bridge Abutment Replacement

D’Appolonia redesigned the proposed abutments for a bridge in Greensburg, Pennsylvania. The change allowed construction to be completed two months earlier than anticipated and resulted in cost savings of $500,000.


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