Design And Monitoring Data Analysis Of A Deep Foundation Pit Support Scheme In Haizhu District

Deep foundation pit engineering is a comprehensive discipline,with special regional characteristics.This paper starts with the foundation pit support project of the housing placement of Haizhu District Eco-City(Beishan Village),Through the design of the foundation pit supporting scheme and the analysis of the monitoring data,the deformation law of the foundation pit excavation can be obtained,which can provide reference for similar projects in this area.The main work content is:(1)Refer to the current research on foundation pit support structure selection and detection analysis and research status;(2)Carrying out a summary analysis of the existing commonly used support schemes,combining the site environment,engineering geological conditions and the scale of the foundation pit project,selecting the support form of the pile pile plus the anchor line,the row pile and the inner support;(3)According to the engineering geological conditions and the surrounding load conditions,the foundation pit calculation model is established in sections,and the calculation of the design scheme and the result analysis are carried out;(4)Analyze the statistical on-site monitoring data and compare it with the calculated theoretical values.Through analysis and research,the following conclusions are drawn:(1)During the implementation of the project,the displacement deformation rate of the foundation pit is accelerating with the increase of the excavation depth.The displacement deformation rate of the foundation pit is the largest in the earthwork with the excavation of 12.9m to the bottom of the foundation pit.After the excavation of the foundation pit is completed,the cumulative displacement value reaches the maximum.The comparison between the theoretical value of the design calculation and the monitoring data shows that the deformation trend of the displacement is basically consistent.(2)In terms of the deformation value of the foundation pit displacement,the theoretical calculation value of the design scheme is larger than the actual measurement value,mainly in the design calculation process,using the two-dimensional calculation model and considering the segmentation.In each region,the most unfavorable situation is used as the calculation model,and the distribution of real soil layers is simulated by the uniform distribution of soil layers,which will inevitably lead to the calculation of theoretical values larger than the measured values,which is also in the perspective of safe implementation of construction projects.considerate.(3)According to the field measurement data,the deformation of the GH section of the foundation pit support is the largest.According to the borehole data of the control foundation pit,there are two layers of the silt layer with a cumulative thickness of 5.5m,which is the base pit.The maximum thickness of the sludge layer and the depth of the lower layer are buried to 6.9 m.The internal friction angle and cohesive force of the silt are smaller than those of other soil layers,and have a great influence on the deformation of the foundation pit.(4)The influence of groundwater level is reduced in the early stage of settlement before the foundation pit.In the later stage of foundation pit implementation,the surrounding surface settlement is mainly affected by the lateral displacement of the foundation pit,and the deformation tends to be stable after the foundation pit is completed.(5)During the process of applying the last anchor cable and excavating the fourth layer of soil in the foundation pit,the growth rate of each deformation value of the foundation pit monitoring reaches the maximum,which is the key risk point of the project construction.