Study On The Mechanism Of The Combined Support Structure Of SMW And Anchorage Cable

Since the introduction of SMW method from Japan in 1990 s,the deep foundation pit support has been injected into the geotechnical field of our country,which has greatly promoted the construction of our country's infrastructure.This support method has many advantages,including fast construction speed,short construction period,high support quality,low cost,energy saving and environmental protection,etc.It is widely used in coastal areas of Shanghai,Zhejiang and Fujian.However,due to the immaturity of design theory,the backwardness of construction machinery and the serious lack of construction experience,it is a pity that it has not been popularized and applied in the whole country.Our country is in the golden period of rapid economic development.All kinds of high-rise buildings are springing up like bamboo shoots,including various underground transportation hubs,underground supermarkets,underground gymnasium and other underground facilities.Therefore,the most serious problem facing at present is the problem of supporting deep foundation pit.In recent years,malignant accidents of deep foundation pit support continue to occur,resulting in serious casualties,and at the same time causing serious adverse effects to our society.Therefore,it is urgent to expand the application of this kind of supporting method with many advantages.The research topic of this paper is to take the Lujin Dongcheng project in Jinan as an engineering example,through the real-time monitoring of the whole foundation pit construction stages,and then to analyze the monitoring data.The deformation characteristics of deep foundation pit under the combined support scheme of SMW anchor cable are studied.The main research contents are as follows:(1)Combined with the engineering data of Jinan Lujin Dongcheng Foundation Pit Project,the design and calculation theory of SMW method is summarized and arranged,and the internal force,displacement and settlement of the foundation pit are calculated by using Lizheng 7.0 deep foundation pit calculation software,and the overall stability of the foundation pit is also analyzed.The anti-overturning stability and anti-uplift stability are checked and calculated.The results show that the support method of SMW method meets the requirements of the design code.(2)The main points of foundation pit monitoring are summarized,including pile top displacement,pile body displacement,surrounding surface subsidence,anchor cable axial force and groundwater monitoring.In addition,the construction technology of SMW method,the causes of common accidents in construction and the corresponding measures are also summarized and introduced.(3)Use MIDAS/GTS finite element software,by analyzing the parameters of the soil layer,The elastic modulus and Poisson's ratio of each soil layer and anchor cable of foundation pit and the Poisson's ratio are analyzed and the finite element constitutive model is established to simulate the change of internal force and displacement of pile in every construction stage.With the help of origin9.0 software,the simulation and measured curves are compared,and the final displacement of the pile top,the displacement of the pile top in each stage of foundation pit construction,the horizontal displacement of the deep layer of the pile,the settlement of the surrounding surface are obtained through the comparative analysis.Some rules of axial force change of anchor cable can provide some meaningful guidance for the construction of deep foundation pit support with smw method.