Three-dimensional Axisymmetric Arc Method for Basal Heave Stability of Circular Excavation

Spatial effects and enclosure structure are ignored in the design process of the circular excavation. And in order to solve this problem, based on the circular arc sliding model of limit equilibrium method, a three-dimensional axisymmetric arc sliding method (TAASM), in which the stiffness of the enclosure structure was considered, was proposed. The spatial effects also was considered by including the circumferential stress, which was deduced in terms of the elastic foundation beam method and the circular ring axisymmetric method, action on the sliding surface in TAASM. Furthermore, the TAASM was applied to check a practical engineering and its result was compared with other method results. Also, the effects of certain factors or parameters, including the maximum lateral displacement, radius of excavation, excavation depth, embedded depth and parameters of soil were analyzed. Results show that:the TAASM considers not only the effects of the enclosure structure stiffness and deformation but also the spatial effects of circular excavations on the sliding surface and its result is relatively reasonable; in circular excavations, the ability of mutual constraints between the sliding body and adjacent soil, the spatial effects of self-stability and the calculated basal heave stability safety factor obtained by TAASM decrease simultaneously with the increase of the maximum lateral displacement of enclosure structure; by TAASM, the calculated safety factor of basal heave stability for circular excavations is larger than that by any other existing plane algorithm, so the embedded depth of enclosure structure may be optimized to lower the enclosure structure cost.