| Case histories of the distortion of and damage to structures adjacent to tunnels and excavations were investigated. Both ground movements and building response were measured at two test sites in Washington, D.C. The structures at the two test sites were instrumented to measure settlement and tilt of the walls and foundations, and lateral and diagonal displacements between the column lines and the bearing walls at various floor levels. From these data, the angular distortion, tilt, lateral extension, shearing and bending of the structures were determined.; Additional data were gathered at other sites in Washington, D.C., and Chicago through construction records and field inspections. The ground surface settlement data, building response data, and the progress of excavation data were compared and related.; Supporting analyses and parameter studies were made and related to the field data. A deep beam model that included the effect of horizontal strain was employed to investigate the response of brick bearing walls to excavation-induced ground movements. The FINITE program was used to model the behavior of frame structures adjacent to open cuts.; Criteria, that considered both lateral strain and angular distortion were developed. The criteria compared favorably to the field data gathered, existing criteria for buildings settling under their own weight (no lateral strains), and criteria (based on lateral strains only) for damage due to mining. As lateral extension strain increased, the tolerance of structures to angular distortion decreased. Minor architectural damage to brick bearing wall structures developed when angular distortions and lateral extension, due to excavation-induced ground movements, were both approximately 1/1000. Infill frames began to experience damage at angular distortions and lateral strains of about 1/750. In contrast, minor damage to buildings settling due to self-weight began at about 1/500. For structures adjacent to excavations, the convex-shaped settlement profile produced a condition where the lateral strains and angular distortions were additive in their effect on the total extension strains in the buildings.; The study showed that the most useful relationships between building damage and distortions could be established when both lateral strains and angular distortions were measured. However, some estimate of the lateral ground strains affecting a structure could be made based upon the settlement slopes if the settlement profile shape, and the size and position of the structure with respect to the settlement profile were known. Once a reasonable estimate of the ground movements caused by an excavation was made, the figures and tables presented in this report could be used to estimate the response of a structure and the resulting damage. |
