The Theory And Numerical Analysis On Settlement Of Adjacent Pile Foundations Due To Tunnel Excavating

Construction of urban metro tunneling is inevitable restricted by existing environment, and many tunneling are built along city roads, running through pile foundations of overpasses. Tunneling is certain to disturb ambient ground, and it may cause settlements or differential settlements of adjacent piles in certain range, which, if excessive, would affect the normal operation and safety of the overpass.Analysis of this paper focus on the influence of the tunneling construction on adjacent piles which be carried out with below aspects.1. Adopting the analytical two stages method, free-field ground movement induced tunneling construction can be obtained. Then the negative skin friction around the pile can be obtained by pile-soil interaction been simulated by a series of continuously distributed springs. Including the bottom bearing effect of the pile, the settlement and axial force of the pile foundations (single pile, group pile) can be obtained, and the effect of pile settlement due to the differential of the main parameters of the pile foundation (pile radius, pile length, the horizontal position relation with pile and tunneling, the space between piles of group pile .etc) is analyzed.2. Considering effect of the raft, the shielding effect of adjacent group pile foundation is studied by numerical method based on pile settlement due to tunneling construction.3. On the basis of triaxial rheological test research of adjacent soil of Guomao region, viscoplastic model parameters of strata which have theological property are obtained. Combined with Guomao underpass construction, data file of three-dimensional time effect analysis is programmed based on FLAC3D code. Compared with the data file of three-dimensional effect analysis, variation regularities of ground and pile foundation settlements induced by tunneling construction with time are studied.