Cooperative Working Mechanism Of Newly-built Embankment Pile-slab Wall And Existing Cantilever Retaining Wall

With the vigorous development of my country’s railway construction,the reconstruction of existing railway lines and the new construction of adjacent existing lines are increasing.Due to the increase in transportation volume and transportation routes and the restrictions on existing line conditions by urban construction,the existing supporting structures cannot satisfy the widening requirements.When the subgrade is required for slope retraction and cannot bear the load of the new wide subgrade,a new supporting structure must be installed for the wide subgrade.At this time,the earth pressure generated by the wide subgrade is borne by the new supporting structure and the existing supporting structure..Based on the construction of a new pile-slab wall on the slope of a certain section of the existing cantilever retaining wall from the Zhongwei-Lanzhou railway line into the Lanzhou hub,this paper uses field testing,theoretical analysis and numerical simulation methods to focus on the new pile-slab wall and the existing cantilever retaining wall.The collaborative work relay research with cantilever retaining wall mainly includes the following contents:(1)By consulting data and reading related literature specifications,understand the current research status of composite retaining structure engineering and pile-slab wall engineering at home and abroad,summarize the design method,working mechanism and form of the pile-slab wall,and obtain some relevant soils.Pressure calculation method,requirements of pile-slab wall design and internal force calculation method.(2)Analyze the pile body bending moment,displacement and earth pressure by burying soil pressure sensors,rebar gauges and inclination pipes on the back side of the pile and the pile body and tracking and collecting data to analyze the pile body bending moment,displacement and earth pressure under the action of the wide filling load of the subgrade side of the composite supporting structure The law of change.(3)Midas GTS NX finite element software is used to carry out three-dimensional numerical simulation analysis,and the distribution law of displacement change and earth pressure of the newly built pile and the existing wall,as well as the relevant data of shear force and bending moment of the newly built pile body are obtained.The relevant data are used to draw graphs to show the corresponding distribution law and change trend.By changing the pile length,pile spacing and pile section size,the displacement and deformation of the pile body,the change of internal force and the change of the earth pressure and displacement of the existing retaining wall are compared and analyzed.(4)Analyze the distribution characteristics of earth pressure of cantilever retaining wall under the condition of existing embankment and combined retaining structure,check and calculate the service state of the existing retaining wall,evaluate the service state of the existing retaining wall,and analyze the load proportion of the new pile and the existing wall to get the load sharing ratio of the old and new retaining wall.