Research On Excavation And Supporting Technology Of The Deep Foundation Pit At Coastal Fly Ash Dredger Fill Area

With the development of city construction and city transformation, the foundationpit is in the direction of large depth and large area. Some China’s coastal region isformed by fly ash formed by power plant. There is some compression of the foundation,low ground bearing capacity, strong permeability, ease to liquefaction and loss at coastalfly ash dredger fill area. There is no experience can be found in the deep foundation pitengineering, the foundation excavation and bracing is a difficulty.This aticle introduces the present situation and development of the foundation pitengineering, also introduces a new technology of excavation named hydraulic soileduction method and made a detailed description, and research from the foundation pitexcavation, support and monitoring. The main contents are as follows：Firstly, make a brief introduction to the deep foundation engineering backgroundand present research situation. Briefly describes the geological characteristic of coastalfly ash, and discusses the research content and purpose.Secondly，on the basis of reading a large number of documents, combined withengineering practice, introduces the deep foundation pit engineering design andconstruction of basic theory. From both sides of the excavation and support of theearthworks on the construction plan of the coastal fly ash dredger fill area. InExcavation, earthwork excavation of the new technologies were described indetail,including feasibility, construction technology, construction scheme selection,hydraulic soil eduction device for supporting, hydraulic soil eduction costs. Hydraulicsoil eduction method is a kind of simple construction, low pollution, high efficiencynew method, compared to the traditional methods, saving a lot of money and also hasthe advantages of convenient construction. Introduced the basic theory of the excavationsupport system,and analysis of coastal fly ash dredger fill area foundation pit excavationsupport program characteristics, to prepare for the future scheme selection.At last, according to the actual situation of “Qingdao municipal solid waste transferstation in Taiyuan road relocation project”, discussion how to determine a reasonablefoundation pit excavation and support scheme, combined with coastal fly ash dredgerfill area actual characteristics, Select the hydraulic discharge method for excavation offoundation pit, slope, soil nailing wall for foundation pit support, spiral pile waterproofcurtain for groundwater control. The common problem in coastal fly ash dredger fill area are insufficient bearing capacity of foundation pit, soft ground, easy to collapse,high underground water level, etc, and pinpoints the problems and propose effectivesolutions. After the actual calculation, analysis and excavation monitoring, it proves thatthe scheme satisfies the engineering requirement.