GEI provided engineering services for a proposed high-rise development with 2 levels of underground parking at 1998-2000 Bathurst St. The proposed structure is in a high-density neighbourhood with two mid-rise buildings and residential homes surrounding the property.
GEI’s services included the design of the excavation support system for the entire perimeter of the underground parking structure. The shoring design was complex as it required the retention of two adjacent structure foundations (2002 and 1998 Bathurst) using interlocking secant pile (caisson) walls braced with multiple rows of post-grouted tieback anchors. Along the east and west perimeters of the site, and where encroachment agreements were not attainable, the excavation was supported using soldier piles and lagging walls braced with corner struts, rakers, post-grouted tieback anchors, and face walers.
Prior to the commencement of demolition and construction, GEI completed an assessment that determined the vibration zone of influence (ZOI) beyond the limits of the site’s property line. The assessment intended to identify surrounding structures that fell within the established ZOI and measure/monitor the range of demolition/construction-induced vibrations, as well as complete pre-construction condition surveys to protect the owner from gratuitous claims for damage.
GEI completed detailed photographic pre-construction condition surveys of 2002 Bathurst, as well as all the surface infrastructure along Bathurst Street. The surveys documented existing deficiencies such as cracks, etc. Once the shoring construction had begun, GEI completed interim field review site visits throughout the process to ensure that all the shoring system elements, including piling, steel section sizes, bracing, etc., were constructed/installed in accordance with the design drawings. Part of this quality verification process included testing the tieback anchors to confirm the tieback grout-to-soil adhesion values. Two performance tests were completed to 200% of the design working loads to verify adhesion. The remaining tieback anchors were proof tested to 133% of their design working loads and locked of at 100% of their design loads. GEI provided the client with reports evaluating the results of each test.
To demonstrate that the shoring system was performing adequately, GEI successfully developed and implemented a comprehensive movement monitoring solution consisting of surface settlement points, inclinometers, and precision survey targets to monitor lateral and vertical movements of the shoring system piles. To date, movements have been within acceptable limits and in accordance with provincial standards.
