On The Impact Of Deep Foundation Pit Excavation On Surrounding Environment Control Technology And The Research Of The Project Cost

With the development of city construction,people pay more and more attention on the development and utilization of underground space. In the city that has full of tall buildings,deep foundation pit construction has become a necessity trend,especially old city reform. In the process of pit excavation, people not only to meet the safety of foundation pit itself, but also control the influence that excavation on surrounding environment. As the result, the surrounding buildings (structures), underground pipelines and surrounding roads are safe and normal.So, the research on the deformation law of foundation pit and the technology of control has become a necessary task. In this passage,we take the engineering of Beiwanzi alley No.11Institute as an example, study on the foundation pit deformation control by using field deformation monitoring, numerical simulation and engineering cost analysis method. The main results and conclusions are as follows:1. Analyzing the foundation pit deformation rule and mechanism. Based on the measured deformation data, finding the feature that foundation pit’s deformation increasing obviously in the adjacent row aisle Road,midspan and external corner. People should take some deformation control designs to deal with these parts.2. Through the contrast of three kinds of supporting schemes,researching on them for foundation pit deformation rule by using numerical analysis method. The results show that:(1) The horizontal displacement deformation of pile anchor bracing shows the phenomenon that upper big lower small. Composite soil nailing wall presents entasis displacement curve.The largest displacement of the upper soil nailing wall and the lower pile anchor support occurs in the2m place.That is the place soil nailing wall.The distortion paths are similar to pile anchor bracing.At the same time,We find that prestressing anchor is very effective on the control of horizontal displacement of the slope protection pile.(2) Deformation laws of basement uplift by different supporting ways are roughly the same. The maximum uplift position is in the basal central.Besides, deformation amount is directly proportional to excavation depth.(3) The ground surface around settlement curve of pile anchor retaining structure approximate to parabolic distribution.The deformation shows the trend that first increases.then decreases to zero. Ground surface settlement is located at H distance of pit wall (H is foundation pit excavation depth). The settlement curve of composite soil nailed wall Indicates that settlement curve approximates linearly. The largest settlement occurs in the pit edge. The settlement curve of the upper soil nailing wall and the lower pile anchor support is similar to pile anchor structure’s. The settlement is more than the pile anchor structure settlement.3. Putting forward the optimization design of foundation pit supporting. That is on the basis of the deformation control of foundation pit design, according to the monitoring of building foundation pit engineering constraint foundation pit deformation, cost analysis,and determine the optimal scheme of foundation pit support.