Numerical Analysis Of Effects Of Different Ways Of Reinforcements On Deformations Of Deep Foundation Pit

With the acceleration of building process of Chinese urbanization, the size of excavation is becoming larger. The foundation pit is poorly designed which affected its stability and safety and normal use of the surrounding infrastructure and buildings. Pit bottom reinforcement can improve the physical and mechanical indexes of the soil which can suppress deformation and improve the stability of foundation pit. But the cost is high, determining a reasonable reinforcing area, selecting the appropriate reinforcing way and combinations become very important.In this paper, on the basis of the three-dimensional model established by using the ABAQUS finite element software, the influence of pit bottom reinforcement in deep foundation pits on deformation of foundation pit was simulated. The influence of different factors and ways of pit bottom reinforcement on the pit bottom upheaval and lateral displacement of the retaining structure were discussed, and the influence of(pit bottom reinforcement+ piles) on deformation of foundation pit was explored. Main research contents and contributions are as follows:1. The analyze of the influence of different factors(Stiffness, width, position change of the reinforced object)on the pit bottom upheaval and lateral displacement of the retaining structure presents that:with the increase of the stiffness and width of the reinforced object, the pit bottom upheaval and lateral displacement decreased, but they exists a critical reinforce range; deformation of foundation pit increased along with the distance between the reinforced object and the bottom of foundation pit became larger, so pit bottom reinforcement should start at the excavation face in bottom.2. The influence of different reinforcement ways(the full bottom pit, skirt edge, ribbon and grille) on the pit bottom upheaval and lateral displacement of the retaining structure were discussed, and the results showed that: the inhibitory effect from large to small is full pit bottom, grille, ribbon, skirt edge reinforcement, and skirt can effectively reduce the pit bottom upheaval within the scope of soil reinforcement. But for the lateral displacement of the retaining structure, the four reinforcement ways have little difference.3. The influence of the four reinforcement ways(the full pit bottom reinforcement, piles, the full bottom pit reinforcement plus piles, skirt edge reinforcement plus piles) on deformation of foundation pit was explored, and the results showed that: the inhibitory effect from large to small is the full bottom pit reinforcement plus piles, skirt edge reinforcement plus piles, piles, the full pit bottom reinforcement; piles have little effect on lateral displacement of the retaining structure, and remained three kinds of different reinforcement ways have little difference.4. Based on the different geological conditions and pit deformation control requirements, choosing a reasonable reinforcement way and the combination of different reinforcement methods not only can meet the requirements of security and environmental impact of the foundation pit, but also can reduce its costs.5. Based on Simulation analysis combined with engineering examples, the consistency of simulation values, calculated values and measured values, verified the rationality of finite element model and correctness of the law based on theory and numerical simulation analysis.