SLEX 2008 UPGRADING: South Luzon Expressway’s SAN JUAN BRIDGES’ REPLACEMENT to be executed with no traffic stoppage.
In 2007 Foundation Specialists was awarded by MTD the Seismic Retrofitting and widening of (7) seven Bridges of South Luzon Expressway Bridges, the construction of Concrete Box Culverts, Anchored Seismic Retaining Structures, and the total replacement of the (2) two long bridges meters above the San Juan Water Reservoir of Calamba City, including the Approach to each of the Bridges Design and Supervision of MTD’s SLEX retrofitting and Upgrading Project was “RENARDET” and DPWH PMO in charge for the project was URPO.
For the Logistical Support to the Project, FS rented a large piece of land overlooking the north side of the water reservoir, with access from the Expressway, and set camp there for the equipment service area, the casting beds for the Bridges’ Post-Tensioned 40m AASHTO girders, the stockpiling of fabricate post-tensioned girders, and for the rebars’ stock yard and fabrication area . The high strength Concrete Mix for all the Bridges was supplied by FS Ready Mix Plant (INSERT OLD PICTURE OF PLANT here) located at Km 19 of the South Expressway Service Road.
While Design did not require total removal of the existing seven SLEX bridges to be retrofitted and widened (INSERT PICTURES HERE) and while a segmental construction scheme was adopted for the excavation and construction of the RC Box Culverts (INSERT PICTURE HERE) traversing the Expressway, all of which only required proper traffic management to avoid traffic disruption, the old two long Bridges over the San Juan Water Reservoir had to be removed totally and replaced with 3 bridges designed in accordance with the latest Seismic Design parameters. The Contact of FS required maintaining continuous opening of 2 bridges, throughout the duration of the bridges’ removal and construction of the replacement.
The Design of the 3 new San Juan Bridges required the construction of the center piers (30 m high columns) right at the center of the deep water reservoir, the construction of a Seismic Resistant Slope Support for the very high soil slope fronting the South Abutment of the 3 Bridges, which abutment had to be provided with a System of Post-Tensioned Permanent Ground Anchors in order to be made Seismic Resistant.
In order to be able to totally remove the 2 old Bridges over the San Juan Water Reservoir and replace it with 3 new bridges, FS prepared a construction scheme for the common construction on Bored Piles pf the three Bridges Center Pier, which by design was positioned right in the center of the Water Reservoir. For that purpose an access had to be built to the south side of the reservoir from the highway (PUT PICTURE HERE} to set the equipment and bring in steel sheet piles and back fill material for the cofferdam needed to be built for the execution of the Bored Piles, the constriction of Plice cap, the construction of the six columns common base and for the columns construction. Under the direction of Surveyors with Total Stations, sheet piles were driven, interlocked, into the bottom of the reservoir to form the Cofferdam (PLACE PICTURES HERE ). Once all the sheet piles were installed, FS installed walers and props, dewatered the cofferdam enclosed area and backdilled the area to builds a working platform for the equipment to be brought in for the drilling of Bored Piles under static bentonite suspension, the installation of prefabricated reinforcing bar cages and casting of concrete. (PLACE PICTURES HERE)