Analysis Of Force And Deformation Of Foundation Pit Support Based On Displacement-earth Pressure Model

In the past ten years,the country has successfully released the creative potential of Chinese people.China's economic development has achieved world-renowned achievements.In order to protect people's well-being,the country has invested a lot of energy in urbanization projects and infrastructure construction projects.With the continuous advancement of construction,subway construction,tunnels,pipe galleries and underground fortifications,the design and construction requirements for foundation pit projects have also been continuously improved.Among them,the issue of control over the deformation of foundation pits will receive more attention.Therefore,this paper proposes an analysis method of foundation pit support based on the displacement earth pressure model with the support of the National Natural Science Foundation of China(41572298),and analyses the lateral reinforcement structure in the supporting system,and derives the calculation formula for the stiffness coefficient of the bolt considering the soil properties.The main work and results of the paper are as follows.(1)To deal with the problem of nonlinear changes between the soil load and the support deformation distributed on the support structure in the deep foundation pit.By introducing the curve shape development coefficient to improve the existing displacement earth pressure calculation method,combined with the influence of the displacement factors of the support structure,a new earth pressure-support structure displacement calculation model was established.In this way,the deformation process of the supporting structure is described,and the nonlinear relationship between the earth pressure and the supporting displacement is reflected,which reflects the common deformation of the internal support in the supporting process.Combined with engineering examples,a calculation program for foundation pit support was compiled based on the MATLAB platform.The calculation results and engineering measurement data were compared and analyzed.The results show that the calculation model can better reflect the existence of the earth pressure and support horizontal displacement.The non-linear change characteristics can get effective calculation results.(2)The concept of Shearing Bands is used to analyze and explain the stress and load transfer characteristics of anchor bolts.Based on the ideal elasto-plastic shear-slip model and the double-exponential curve-slip model,the loading of the anchoring interface is simulated.The load transfer method and shear displacement method are used to analyze and solve the shear deformation at the anchorage interface and the soil outside the interface.Based on this,the formula for calculating the stiffness coefficient of the anchor bolt is deduced.The influence factors of the calculation formula of stiffness coefficient were analyzed.The results show that the stiffness coefficient of the pressure type bolt increases with the i ncrease of anchorage length.However,when the anchorage length is too large,there will be some invalid anchorage segments.There is a positive correlation between the anchorage section diameter of the anchor and the elastic modulus of the grouting body.At the same time,the mechanical properties of the soil are closely related to the stiffness coefficient of the anchor.(3)Based on the displacement earth pressure and the improved formula for the stiffness coefficient of the anchor bolt,a simple calcula tion model for the foundation pit support is established and applied to a foundation pit engineering example.The project is analyzed and calculated.It shows that the horizontal displacement of the supporting method obtained by this method is in good agre ement with the actual measured displacement.This paper adopts this method to analyze the stress and deformation of the pile-anchor support of the foundation pit,which can obtain reliable deformation data of support.