Foundation Pit Supporting Design And Numerical Simulation Optimization Of Guo Xin Shopping Mall

With the accelerating process of urbanization. Foundation pit engineering develops in the direction of bigger and deeper sizes. Supporting engineering is an essential part in the process of building pit. It has become the mainstream of foundation pit research to seek a safe, low cost and convenient for installation of supporting way. Practice proves that it has particular advantages in using rowed piles and concrete internal supporting system in deep foundation especially in soft soil ground, such as little deformation without crossing pipelines.In this paper, the research system includes the selection of foundation pit, supporting design, stability checking and numerical simulation. The main contents of this paper are as follows:(1) With research on the foundation pit engineering of Guoxin shopping mall, supporting form of row piles-two tracks braced retaining system is choosed for the case project according to the supporting scheme selection principle and surrounding conditions. The built-in depth of pile is 9.0m, the pilespacing is 1.3m, and the diameter is 0.9m. The braced retaining structures is made of reinforced concrete, with a cross-section of 0.8m×0.8m. Besides, using FRAWS to analyze the supporting system including structure calculation and stability checking. It shows that the calculation results of structural overall and partial stability comply with the relevant design specifications. Then verify the reliability and rationality of the presented scheme.(2) According to the principle of the finite element method, through selecting the constitutive model, setting the model size and boundary condition, determining the initial stress condition, the paper evaluates finite element analysis of excavation of foundation pit by using ABAQUS. Based on the study of displacement field of foundation pit, the paper analyze the displacement of internal-external soil of pit, the displacement of fender piles, the displacement of inner support, and the axial force of inner support. The simulation results show that the maximum value of the ground surface settlement is 13 mm, the maximum horizontal displacement of the pile is 15 mm, the maximum axial force of the two support are 3703 k N and 6225 k N. The results are in an allowable maximum range. Consequently it makes a further validation of the reliability and rationality of the presented scheme.(3) By using the result of simulation to optimize the supporting system design and monitoring design: It is better to increase the amount of reinforcement of piles where 4~11m and 14~18m away from the top location, and it should be promoted as a key monitoring. The cross section of the first support should be appropriately reduced as its xial force is much less than the latter support beam. The second beam should be focused on monitoring, especially at the final stage of excavation. Increases the observation frequency of pipeline and building within a 15 m distance away from pile.