Deep Foundation Pit Support Design,Numerical Simulation And Monitoring Analysis

With economic development,deep foundation pit projects continue to increase.In order to deepen the research on deep foundation pit engineering,this thesis is based on a certain foundation pit project in Beijing.7.0 software for design calculation,use PLAXIS3 D software to simulate the soil displacement,the displacement of the enclosure structure,and the internal force of the enclosure structure.Impact of pit stability.Analyze the measured data,study the change law of the measured data parameters,and compare the measured data with the simulated data.The results show that:(1)The stability of the supporting structure calculated by the Lizheng software meets the requirements of the specification.The maximum ground settlement of 12 mm and the maximum pile displacement of 9.54 mm are also within the allowed range of the specification.Therefore,the selected plan for foundation pit support It is reasonable and safe.(2)The maximum horizontal displacement of soil and enclosure structure obtained by PLAXIS3 D software is 9.73 mm and 9.70 mm at the top of the foundation pit,respectively.The maximum ground settlement is at a distance of 2.36 m from the enclosure structure,and the maximum value is 8.13 mm.Change curve Similar to a parabola,the maximum uplift of the pit bottom is located at 18.78 m from the side wall of the foundation pit,and the maximum is 8.24 mm.These displacement values are within the allowable range of the specification.Due to the binding force of the anchor rod and the soil,the enclosure structure The bending moment and shear force of the anchor rod have obvious changes in the setting position of the anchor rod.(3)The horizontal displacement of the anchor rod under the conditions of 10°,15°,20°,25°,30°,35° is obtained by PLAXIS3 D software simulation,indicating that the horizontal included angle of the anchor rod should be set at 10° to Between 25°.(4)The horizontal displacement of piles under the conditions of pile diameters of600 mm,800mm,1000 mm,1200mm is obtained through PLAXIS3 D software simulation,indicating that increasing the pile diameter to a certain extent does not have a particularly obvious impact on the displacement,so do not increase the pile diameter all the time.To reduce the deformation of the enclosure structure.(5)Through the simulation of PLAXIS3 D software,the cohesive force increased by 0%,20%,40%,60%,and the internal friction angle was taken as the horizontal displacement of the pile under the conditions of 10°,20°,30°,and 40°.As the cohesive force increases,the displacement of the enclosure structure shows a decreasing trend,and the internal friction angle increases,and the displacement of the enclosure structure also shows a decreasing trend.Therefore,the type of support adopted can be improved by improving the shear strength of the soil.optimization.(6)The measured horizontal displacement and surrounding soil settlement are basically the same as the displacement curve obtained by PLAXIS3 D simulation software.The maximum measured horizontal displacement and settlement are 10.09 mm and 7.02 mm,respectively,and the simulated maximum horizontal displacement and settlement are respectively.They are 9.70 mm and 7.44 mm,the two values are not much different,which verifies the rationality of the numerical simulation results and also shows that the numerical model can be applied to actual engineering.