Characteristic Analysis Of The Interaction Effect Of Adjacent Excavations

It is easy to cause group excavations and meet the situation of two or more excavations constructing at the same time since there exists high density of high-rise buildings in urban area. The deformations of supporting structures and surrounding soils caused by the adjacent excavations are quite different from those of the single excavation. The interaction effect of the adjacent excavations must be taken into account at the design and construction stage. The interaction effect factors are distance between adjacent excavations, excavation sequence, supporting structure and so on. The interaction effect of the adjacent excavations makes the stress and deformations of supporting structures and the effect to the surrounding environment more complex. This paper takes Junlinshengshi excavation and Shimao international center excavation in Fuzhou as the research object to analyse the excavation characteristics of adjacent excavations by two-dimensional and three-dimensional finite element model. The main contents of the study are as follows,The finite element software PLAXIS is used to establish the two-dimensional model and the Hardening Soil model is used as the soil constitutive model. The soil movement, the deformations and stress of supporting structures of the adjacent excavations are mainly discussed at the synchronous excavation stage. By considering the influence of distance between adjacent excavations and excavation sequence to the characteristics of adjacent excavations, the influence area of adjacent excavations and the laws of the deformations of supporting structures under different excavation sequence are obtained.Finite element method with reduced shear strength is used to evaluate the base stability of excavations. The two-dimensional model is simulated by the finite element software Phase2 and the excavation failure mode is estimated based on the calculated result. The effect factors of stability of excavation are analysed in detail, such as excavation depth, distance between adjacent excavations, the length of anchor, the embedded depth of pile, soil shear strength, supporting method and the thickness of soft clay.The stress path and the rotation of pricipal stress axis of the soils around excavation are studied during excavation stage at the active and passive side of the wall and at the position where the anchors install. The laws of the changes of both stress path and rotation of principal stress axis at the inner and outer part of foundation pit and the effect area are also obtained.The finite element software PLAXIS 3D is used to establish the three-dimensional model and analyse the excavation characteristics of adjacent excavations at the synchronous excavation stage and with different distance between adjacent excavations. The influence of corner stiffness effect to the excavation characteristics of adjacent excavations is also discussed. The space effect is considered in the three-dimensional analysis and the analysis result is more closer to the actual.