Abstract Foundation pit excavation inevitably causes rebound of the soils within a certain depth range at the pit bottom, leading to the uplift deformation of underlying tunnels, which will pose a threat to tunnel safety if the deformation is significant. To further explore the impact of foundation pit excavation on the deformation of underlying tunnels, based on the elastic theory of layered materials, and considering the influence of the soils on both sides of the pit on the soils at the pit bottom, the vertical additional stress of the soils under internal action of axisymmetric loads in the multi-layered soils is derived using integral transformation and matrix recursion methods. On this basis, the tunnel is simplified as an Euler-Bernoulli long beam placed in a Lifking foundation model that considers the continuity of soils, and the differential equations for controlling the longitudinal deformation of the tunnel under unloading of pit excavation are derived. The finite difference method is used to solve the longitudinal displacement matrix expression of the tunnel. Through comparative analysis of engineering cases, it is found that the results by proposed method are closer to the measured data than the Winkler foundation model, verifying its good prediction effect.
Abstract：
Foundation pit excavation inevitably causes rebound of the soils within a certain depth range at the pit bottom, leading to the uplift deformation of underlying tunnels, which will pose a threat to tunnel safety if the deformation is significant. To further explore the impact of foundation pit excavation on the deformation of underlying tunnels, based on the elastic theory of layered materials, and considering the influence of the soils on both sides of the pit on the soils at the pit bottom, the vertical additional stress of the soils under internal action of axisymmetric loads in the multi-layered soils is derived using integral transformation and matrix recursion methods. On this basis, the tunnel is simplified as an Euler-Bernoulli long beam placed in a Lifking foundation model that considers the continuity of soils, and the differential equations for controlling the longitudinal deformation of the tunnel under unloading of pit excavation are derived. The finite difference method is used to solve the longitudinal displacement matrix expression of the tunnel. Through comparative analysis of engineering cases, it is found that the results by proposed method are closer to the measured data than the Winkler foundation model, verifying its good prediction effect.
LV Linhai1,
2,
3 JIANG Mingjie1 etc
.Calculation Method for Underlying Tunnel Deformation Induced by Foundation Pit Excavation Based on Layered Mindlin Solution[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(4): 95-104
2024, Vol. 61 