3-D Finite Element Analysis Of Adjacent Framework Response To Deep Excavation

With the rapid development of our country's economy, more and more construction projects spread in the city, lots of high-rise buildings go into the view of the people. At the same time, the effective utilization of underground space becomes the inevitable requirement of the development of the city. The underground subway, underground parking lot and underground market are very common. While in the construction of foundation pit engineering in the urban areas, the problems of the influence of foundation pit excavation is inevitable. At the same time, it is very difficult to calculate analysis the problem because the surrounding and the structure types is complex. In this paper, a 3 D finite element model is established to analysis the deformation and internal force of the framework. The main conclusion have the following:(1)When the frame structure appears around the foundation pit, the subsidence of the soil will increase significantly, and the whole soil settlement influence area expanded. At the same time, the existence of the frame structure can adjust the horizontal displacement of the soil., and range of displacement adjustment of framework wit bar foundation is much higher than the framework with independent foundation.(2)When the short edges of the framework is perpendicular to the foundation pit, the internal force of the framework changes smaller, but the structure tilts a lot. Therefore, more attention should be paid to the control of different subsidence and tilting.(3)When the foundation form of the frame structure is independent foundation, the internal force of the ground floor beams and columns will be distributed because of the pit excavation. When the foundation form of the frame structure is bar foundation, the internal force of the ground floor beams and columns will not be distributed because the integrity of the framework is quite good. But the internal force will change.(4)With the increase of the pit-frame distance, the bending direction will change a lot. When the framework is close to the pit, the structure will be a concave buckling under deformation, the internal force increase. When the framework is far from the pit, the structure will be a convex buckling under deformation, the internal force decrease. (5)With the increase of the length of the pile, the frame settlement reduce gradually. The pile not only provides the bearing capacity, but also reinforce the soil out of the pit. When the pile is short, the reinforcement effect is not obvious, but with the increase of the length of the pile, the reinforcement effect significantly increased.(6)With the influence of the pit excavation, the smaller the stiffness of the pile, the greater the deformation, and the smaller the additional bending moment of the pile. At this time, the additional deformation of the upper structure is bigger, which make the upper structure damage before the pile destruction. When the stiffness is great, the pile deformation is small, but the additional bending moment is bigger, at this time, the pile may damage first.