Research On Optimizing Of One Deep Foundation Pit Supporting Scheme Based On Value Engineering

In recent30years，the urban construction industry has a rapid development. Now the scaleof underground space development is bigger and bigger along with emergence of high-rise andsuper high-rise buildings and day-by-day increasing of all kinds of large-scale engineeringsuch as metro station、the opening-cut tunnel、municipal square、foundation of bridge and etc.Excavation engineering technology in the construction industry is a high risk， although theexcavation engineering accidents across the country rate is decreasing， but still emerging. It’snecessary to find out a set of objective、reasonable and workable scheme of selection method，inorder to get a safe、reliable、economic、convenient construction and environmental protectionsupporting scheme.First, the article describes the geological distribution and characteristics of theGuangzhou area and summaries the common form of foundation pit supporting in Guangzhou:pile anchor supporting structure， the pile brace support structure， the composite soil nailwall and so on. And then the thesis expounds the basic principle of value engineering andapplication value engineering optimization model of foundation pit supporting scheme.Secondly，the thesis chooses a common engineering project in Guangzhou as an exampleand analyses it. First of all，it gets the function index system of foundation pit supportingscheme according to the functional analysis system technology (FAST)，and concludes threealternatives (the composite soil nail wall， piling-interior support and undergroundcontinuous wall)according to the geological and hydrological condition of the engineering andthe surrounding environment. Then it determines the weight of each function evaluation indexby hierarchy analysis theory and0to4scoring method. After that，it gets the function indexesthrough the scores of each alternative scheme which is scored by experts and the cost indexesby estimating ecah subdivisional engineering expenses of each alternative schemes. At last，we can conclude the optimal scheme which has the maximum value coefficient.In the process of engineering cases based on value engineering principle， the study findsthat function analysis is the core of value engineering and the difficulty is to determine thefunction weight. And it comes to a conclusion that the optimal scheme is pile-support schemefrom the results of the implementation. Because it’s safe and reliable， and it has smalldeformation. Besides it makes the project finish5days ahead of schedule and save3.8%cost. To sum up， the thesis provides a simple， quick and accurate model for selecting theoptimal supporting scheme of deep foundation pit.