| In order to effectively alleviate the current pressure on housing and transportation,my country has begun to increase the development of underground space,and has invested a lot of resources for this,which has promoted the sound development of deep foundation pit projects.During the construction of the subway,because of the particularity of subway foundation pit location,and there are more stringent requirements for deformation control at will,in order to ensure higher safety during the construction of the deep foundation pit.Therefore,it is very important to conduct a comprehensive study on the influence of groundwater control and support conditions on its deformation during the excavation process.This article explores the specific construction process of a subway station set up in Chongqing,systematically analyzes various projects carried out in order to effectively avoid deformation,such as groundwater control and support during the excavation of deep foundation pits.Carrying out on-site monitoring and collecting relevant data,analyzing the laws of ground settlement and changes in the form of the enclosure;giving full play to the effectiveness of the finite element software,setting up corresponding mathematical models for the development process of foundation pit engineering,and analyzing the occurrences during the construction period.Carry out a comprehensive simulation of the ground subsidence and deformation of the retaining piles,and compare the simulated data with the measured data to effectively verify the reliability of the model itself;comprehensively analyze the impact of the deformation of the deep foundation pit various factors,based on geology and design,analyze the specific impact of these factors.The final conclusions are:(1)The field investigation and construction data monitoring are carried out,the ground settlement data around the foundation pit are analyzed,and the surrounding settlement law in the process of deep foundation pit excavation is summarized.The ground settlement presents"groove" deformation,and the maximum settlement position is 5m away from the foundation pit.The horizontal displacement of the top of the retaining pile increases with the excavation,the axial force of the anchor cable changes more stable,and the anchoring effect is better.(2)Through the comparison between the monitoring data and the deformation results of the deep foundation pit simulated by the software,due to the "spatial effect" of the deep foundation pit,although there are some differences in the data comparison,the error is within the allowable range,which verifies the rationality of the deep foundation pit support structure design and model.(3)The settlement curve around the deep foundation pit changes in a "groove" shape,and the settlement increases gradually,with the main influence range of 0-20M;The horizontal displacement of the retaining pile increases gradually,and the maximum deformation of the foundation pit moves down gradually,and the deformation curve is in the shape of "parabola"with small on both sides and large in the middle;The locking value of Anchor Cable axial force is large,and the axial force change is relatively stable,which effectively limits the displacement of retaining pile;The ground heave at the bottom of deep foundation pit increases with the excavation.(4)by increasing the diameter of the retaining pile and retaining piles embedded depth of soil,the maximum horizontal displacement of retaining pile will be reduced,but there is a"boundary effect",and the effect on the deformation of the deep foundation pit gradually decreases;The design parameters should be selected reasonably.With the increase of the cohesion and the Angle of internal friction,the horizontal displacement of the retaining pile and the ground settlement gradually decrease,and the relationship is inversely proportional.With the increase of Poisson’s ratio,the horizontal displacement of retaining pile gradually increases in a proportional relationship. |
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