Deformation Monitoring And Prediction Of Deep Foundation Pit In Expansive Soil

With the pace of China's urbanization process,the rapid development of urban high-rise buildings,deep foundation pit works like a dotted appearance.Deep foundation pit construction site in the vast majority of the city center,the surrounding environment is complex and sensitive,Such as deep excavation works around the number of buildings and intensive,the surrounding roads or surface water and other pipelines are intricate,in the past deep road pit around the road traffic flow is huge.If the deep foundation pit project deformation is too large,will give deep foundation pit engineering and the surrounding environment has serious consequences,In the deep foundation pit engineering and the surrounding environment safety accident summary classification,the special nature of the problems brought about by the safety accident often bring us painful lessons.At the same time,the current "construction pit engineering monitoring technical specifications" GB50497-2009 Article 1.0.2 clear the surface of the specification does not apply to the rock construction foundation pit engineering and frozen soil,expansive soil,collapsible loess and other special soil and erosion Environmental construction of foundation pit engineering monitoring.Therefore,it is necessary to explore and study the deformation and prediction of foundation pit engineering which does not apply to the existing norms.Expansive soil is one of the most representative of the special soil,In this paper,Taking the Shufeng 468 Supe High Project of Chengdu Greenfield Center as an Example.the project foundation pit project belongs to the typical deep excavation project in expansive soil area.On the basis of deep understanding of deep foundation pit engineering and neural network in expansive soil area,The deformation mechanism of deep foundation pit in expansive soil area and the main influencing factors of deep foundation pit engineering deformation in expansive soil area areexplored,This paper introduces the deformation monitoring of the deep foundation pit project that Shufeng 468 Supe High Project of Chengdu Greenfield Center,and analyzes the deformation data of the project instance,Finally,BP neural network is used to predict the horizontal displacement of the deep foundation pit.This article mainly to do the following work:(1)The deformation principle and deformation type of deep foundation pit engineering in expansive soil area are expounded,and the observation and forecasting methods of deep foundation pit engineering deformation in expansive soil area are analyzed,and their advantages and disadvantages are summarized.(2)Aiming at the green grass center of Chengdu,the special program of deep foundation pit project of Shufeng 468 super high project and the deformation monitoring system of deep foundation pit engineering in expansive soil area,During the construction period,the monitoring categories were observed,analyzed and processed,It is concluded that the deformation of the pile top in the three supporting concrete supports the "N" shape change rule,and it is superior to the concrete support+ four anchor support in the control horizontal direction deformation.(3)Introduce the BP neural network model method and principle,combined with the engineering characteristics,The excavation depth of excavation,the depth of excavation,the type of supporting structure,the grade of rainfall,the five influencing factors of active earth pressure and the quantization as input,Using Matlab software as the platform,BP neural network is used to determine the forecast model applicable to the project.(4)Using the Chengdu Greenfield Center · Shufeng 468 super high-rise project deep foundation pit engineering deformation monitoring data as the test data,the forecasting model to test,The relative error of the prediction results is within ± 10%,and the prediction accuracy is high,which can meet the requirements of engineering use.It shows that BP neural network can be applied to the prediction of deep foundation pit deformation in expansive soil area.