Helical Tieback Retaining Wall Saves The Day
Titan Homes is a condo development located in Houston Texas that backs up to a creek. A retaining wall was constructed along the property line adjacent to the creek. The retaining wall varied from 8 to 16-feet in height and was placed 20-feet from the nearest line of 3-story condos. The development was still under construction when the retaining wall began to settle and was failing in sliding and overturning as well. The retaining wall was under-designed for the existing soil conditions and surcharge loads. Stiver Engineering, with assistance from Fortified Engineering, designed a helical tieback system to secure the existing wall and place a new retaining wall 8 to 16-feet below the existing wall.
Time was of the essence as the wall was continuing to settle and rotate towards the creek at approximately ½-inch per month. The stability of the newly constructed 3-story condo buildings adjacent to the retaining wall was in jeopardy.
With the 3-story condos being 20-feet away from the retaining wall and supported on concrete piers, laying out the locations of the tiebacks became a challenge and had to be carefully coordinated to avoid the concrete piers. Ramjack installed a total of (315) 2 7/8” Threaded Connection tiebacks. The existing wall was secured with (105) tieback anchors and a customized 8-inch whaler. The new portion of the wall extending below the existing wall was secured with (210) tieback anchors with 4079 New Construction Brackets embedded into the wall. The tieback anchors average embedment was 40-feet. Ramjack also installed (10) 2 7/8” Threaded Connection helical piles with 4021 brackets, to a depth of 33’, in the location where the existing retaining wall was settling.
For quality assurance, three tension tests were performed in different sections of the retaining wall per ASTM standards to verify the quality of installation and Fortified Engineering’s tieback design which all tiebacks passed. Ramjack fought many days of rain and heat but installed the project on time and within budget.