The Research On Deformation Law And Design Of Deep Foundation Pit Combined Support System

With the development of economy and society,the rise of super high-rise buildings and the utilization of underground space have made the depth and area of foundation pits continue to increase,and the form of support for foundation pits has also ranged from simple to complex.In Chengdu,there are more and more pile-internal support-anchor cable support forms.It is necessary to discuss the deformation law of foundation pits,the supporting effect and the design method of foundation pits in Chengdu.Based on the "Greenland Center·Shufeng 468" deep foundation pit engineering,this paper studies the application of piles-internal support-snchor cable support structure in deep foundation pits in Chengdu area.(1)According to the existing norms,the design and calculation of the foundation pit were carried out by using Lizheng deep foundation pit software and Qimingxing BSC.The design results of two typical sections were listed in detail,and the displacement and internal force variation of design were analyzed.(2)The monitoring results of the foundation pit engineering are summarized.The deep horizontal displacement of the pile foundation,the ground settlement,the vertical displacement of the pile top,the vertical displacement of the column and the axial force of the anchor cable are analyzed in detail.Six monitoring data of internal support axial force,summed up the regularity and characteristics of these deformations and internal forces,and evaluated the application effect of combined support structure and the difference between different support structures.(3)The support design methods of expansive soil area are compared,and the loading of expansion force in software is illustrated.The design of two typical sections is calculated by three schemes.The support structure between different schemes is analyzed and compared.Deformation,internal force,safety factor.(4)Using the Midas GTS NX finite element analysis software to model the three-dimensional foundation pit,further discuss the comparison design method,and analyze the deformation law and characteristics of the combined support structure.Numerical simulations were carried out on different design schemes,and the design calculations of different schemes were combined to give design suggestions for the support structure in the area.After comparison with the monitored values,the overall deformation and support of the foundation pit was simulated by three-dimensional numerical simulation.The structural deformation and the characteristics and laws of the internal forces of the supporting structure were analyzed and summarized.