Deflection and Earth Pressure Measurements of an Anchored Concrete Shoring Wall

This paper presents the data collection and analysis of deflection and earth pressure measurements made on a concrete shoring wall in Atlanta, Georgia. The shoring wall serves as the permanent basement wall for a ten-story parking garage. The wall is approximately 30 feet high and was constructed using steel soldier piles and cast-in-place concrete lagging. The lagging was placed in 4½ foot lifts from the top down and was cast directly against the soil being retained. This soil consists of a thin veneer of fill overlying moderate consistency soils of the Piedmont Physiographic Province. Temporary lateral support of the wall was provided using one to two rows of grouted, tendon-type tieback anchors. Long-term lateral support is provided by the structure which has been constructed against the shoring wall. After completion of the structure, the tiebacks were released. At two locations, inclinometer casing was attached to soldier piles to measure lateral deflections of the shoring wall. In addition, five vibrating wire earth pressure transducers were placed behind the concrete lagging at several heights and varying positions relative to the soldier piles and tiebacks. Both deflection and earth pressure measurements were made as the excavation progressed and before and after tiebacks were stressed. Also, measurements have been taken for approximately one year after completion of the excavation and pressure measurements will be continued indefinitely in the future. The results of the wall monitoring are analyzed and compared with the earth pressure assumptions used in design, as well as other methods used to estimate lateral earth pressures and deflections for anchored wall systems. The measurements made to date, as well as future measurements will also be used to evaluate any changes in earth pressures that may occur over time and assess long-term deflections that occur in these types of structures.