Abstract: Shaft construction in clayey soils typically induces ground movements. This study develops a cavity contraction theory-based analytical framework to predict three-dimensional ground displacements during shaft excavation. The validity of the proposed method was first verified through comparative analysis with published monitoring results. Subsequent parametric analyses systematically quantified depth-dependent variations in surface and subsurface soil deformations induced by circular shaft construction. Surface settlements outside the shaft exhibit a spandrel-shaped profile. This configuration gradually transitions to a concave morphology with increasing depth. Horizontal displacement curves demonstrate an evolutionary pattern: initial hump-shaped distributions progressively develop into arched configurations with depth. Deep soil deformations adjacent to retaining walls exhibit complex patterns, characterized by initial settlement accumulation followed by abrupt stress-release-induced reduction. Horizontal deformation profiles adopt distinctive bow-shaped configurations, featuring maximum magnitudes at mid-depth positions. Soil displacement magnitudes demonstrate linear attenuation with both increasing depth and horizontal distance from the excavation. The spatial influence zone of horizontal displacements extends significantly beyond the vertical extent of surface settlements. Monitoring data emphasize that frequently neglected deep-seated horizontal displacements could potentially affect adjacent infrastructure elements, particularly bridge abutments and subsurface utilities.

Key words: circular shaft, spherical cavity contraction theory, volume loss, soil displacement