Cover-Reverse Impact Analysis Of Excavation Of Underground Structure Deformation

Cover-reverse construction is widely used in the foundation pit engineering in recent years,but in actual construction,deformation control of underground structures has become a big difficulty in construction. In this paper, the research background of deep excavation is hefei Jiaotong building. Construction of this project is using a dig uni-axial cover. In this paper, Through the research of underground structures and deformation and get some conclusions:(1)First of all, First this paper introduces the principle and advantages and di sadvantages,and this paper expounds the uni-axial research status at home and abroad.(2)Reverse construction of the underground structure of uni-axial deformation principle has carried on the arrangement,Including the excavation of soil displacement, uplifts of pit deformation principle, the influence of deformation of retaining structure and the column vertical displacement.(3)According to the hefei Jiaotong building engineering construction, by using the finite element software MIDAS GTS/NX for hefei Jiaotong building model is established in this paper. By different excavation sequence to simulate the excavation process.(4)Obtained numerical simulation calculation crown beam horizontal displacem ent, displacement of underground continuous wall, pillar settlement value. And sort out the Jiaotong building crown beam horizontal displacement, displacement of underground continuous wall, pillar settlement data, and has carried on the comparison and analysis, obtained the variation regularity of deformation in the process of transportation building construction.(5)Contrasted LZC-1and LZC-2 of horizontal displacement monitoring data and simulated data, due to the negative a layer of roof stiffness is too large,crown beam horizontal displacement towards outside the foundation pit. With the increase of excavation depth, crown beam horizontal displacement began to pit. In the field of underground continuous wall deformation analysis, in early foundation pit excavation, the maximum horizontal displacement occurred at top of the wall, as the excavation began to move down, the maximum horizontaldisplacement occurred to the central pile maximum at last. In the roof under the action of horizontal displacement curve is "two big middle small" displacement curve. The final research six columns of differential settlement, obtained at the beginning of the foundation pit excavation, due to excavation unloading of soil, soil stress release caused the uplift and post up. After the excavation to a certain depth, with the increase of excavation depth, pillar uplift has been reduced.