An Analysis Of The Influence For Buildings In Beijing's A Deep Excavation Diging

With the extensive development and utilization of urban underground space,people's demand for buildings is getting higher and higher,and the excavation depth of foundation pit is getting increasingly deep.In high-rise buildings and narrow capital,Beijing,the foundation pit surrounding environment tend to be very complex,therefore,we can ensure that the foundation pit can be excavated normally,also need to guarantee the safety and normal use.The construction of foundation pit works is related to the geological conditions of the site and the adjacent buildings.Due to the concealment of the foundation pit construction,Different areas have different hydrogeological conditions,and different types of support are adopted,and different structures have different impacts for buildings.Therefore,it is of practical significance and application value to study the influence of excavation process on surrounding environment.This paper is based on the typical soil rocks in Beijing's Mount Shi Jing,through the effects of excavation on surrounding buildings are detail studied.The main research work and conclusions are summarized as follows:(1)Analyzed deformation mechanism of foundation pit engineering,summarized and expatiated the related theory of foundation pit excavation to the influence of adjacent buildings.(2)Through understanding the engineering case of a foundation pit supporting project of Beijing,Collected and arranged the monitoring data,and preliminarily obtained the rule of building settlement during excavation: The settlement of buildings caused by excavation is divided into three stages: synchronous settlement and asynchronous settlement and stable stage;For different basic and structural forms,the effect of resisting uneven settlement is different,and the frame structure pile foundation has better resistance to deformation.(3)By using the MIDAS GTS finite element software,the modified morcoulomb model was selected as the constitutive model,and the mesh was divided into a grid of 364,596 units.By numerical simulation of the project,the displacement cloud image of soil and building deformation under the supporting structure of the foundation pit is obtained.In this paper,the deep horizontal displacement simulation of the surrounding pile is obtained,and the variation rule is the bow shape;The surface subsidence and building settlement simulation show that the curve is concave.After comparing the simulation results with the monitoring data.The measured values of horizontal displacement and surface subsidence and settlement of the pile under different working conditions are greater than that of simulation.(4)On the basis of combining theoretical research and field experts,Using the ideal point method of combination weight,the building safety evaluation index is framed,and the various factors that affect the deformation of buildings are evaluated comprehensively to understand the safety state of buildings under different working conditions.The damage grade of the building at the 18 th day of excavation is one level and the building is in a safe state;In the 48 days and 78 days,buildings have a secondary level of safety,and buildings have a slight impact.