The Research And Application For Optimal Excavation Method Of Foundation Pit And The Deformation Control

For the past few years, along with our country economy of booming development, more and more high-rise buildings that mark the developed coastal cities are gradually throughout the country, so the deep foundation pit engineering becomes the primary problem. Despite the deep foundation pit engineering of the construction industry in our country at present not only has formed a set of complete system and has the ability to properly handle its safety and technology, but also has accumulated many experience from successful engineering cases over the years, the foundation pit accident still exist. There are some main reasons:(1)design factors, the design theory system is not perfect;(2)construction factors, the construction personnel technical level is uneven and they can not grasp the construction process and organization well;(3)the informatization construction factors, information monitoring of the construction is the important thoughts of improving the design flaw, and it is also the premise to find out the problem and custom processing scheme efficiently during the construction process. For the demanding construction, the foundation pit excavated deeply or surrounded by the complex environment. With adopting informatization construction, it can effectively control the deformation and ensure the safety of foundation pit.This paper through practical foundation pit project to discuss the excavation method, construction deformation control and informatization construction organization, there are a few main work:(1) To summarize the recent major excavation method of foundation pit, and present the advantages and disadvantages of each excavation method, and at the same time simply introduce the principle of each excavation way to inhibit the deformation. The foundation pit excavation has obvious spatial effect, so it needs to consider that how to choose the appropriate excavation way to weak the influence of spatial effect.(2) First of all, according to the characteristics of the actual excavation engineering projects, it analyzes and compares the excavation methods which can apply to the project, and preliminary sure that it proposes to use the basin excavation, and the foundation pit can be divided into two parts, basin soil and reserved soil. Secondly,1) with using the MIDAS GTS software, it discusses the width of the reserved soil after the pot excavation, and builds four models with four widths of reserved soil,10meters,20meters,30meters,40meters, to simulate the excavation condition, then finally compares the deformation displacement data and determines the optimal reserve width;2) The establishment of10m,20m,30m,40m according to10m multiple segment length, analysis of different segment length impact on the deformation, and to determine the segment length of the ideal; for each segment length to create multiple model discuss the most possible segmentation excavation sequence on the deformation effect, and ultimately determine the section excavation sequence the ideal.3)to establish multiple model and discuss the section excavation method of reserved soil, including the excavation sequence and the block length’s influence on the deformation, and finally find the ideal result.Finally through the MIDAS GTS on various construction parameters of the simulation, comparison of numerical simulation of excavation can be a minimal impact on the deformation, which is the best way of excavation.(3) With using the MIDAS GTS software to obtain the ideal way of excavation, then to organize the project construction, at the same time to combine with the field monitoring data, constantly to adjust the construction sequence and test the model, timely report to superior if there is a problem, to achieve the goal of informationization construction control the deformation.(4) According to the concrete construction technology for the foundation pit project and site environment, to discuss the suitable measures for the deformation control and harmful situation that may occur, and to formulate the specific implementation plan and emergency response measures early, do the beforehand control; Combining with the monitoring data to dynamic implement the deformation control in the construction process, and nip adverse circumstance of signs in time. (5) Monitoring data comparison, applicability analysis of excavation results and model, by changing the parameters of soil and the change of model size, comparison of the displacement change and monitoring data excavation, that conclusion has certain reference value for other foundation pit engineering, at the same time to find and monitoring data modeling dimensions closest.