Research And Design Of Underpinning Component For The Existing Buildings

Development and utilization of urban underground space resources is one of the most effective ways to expand infrastructure capacity, to improve the city's comprehensive disaster prevention capabilities, to improve land use efficiency and conservation of land resources orderly, rational, comprehensive, efficient. Additional layer of earth excavation and underground construction can be done when the existing building have underpinning. Therefore, the study and design of the basic elements of underpinning existing is a key technology to develop underground space.Underpinning technology is raised about using jacked column to develop underground space of existing buildings with independent basis and using steel pipe piles to develop underground space of existing buildings with strip foundation in this paper. The construction of two processes is discussed.By the research of ANSYS numerical analysis about different cross-height ratio of four separate caps, the caps of the cross-height ratio greater than 1 is lever arch, and have bending compression failure; and the caps of the cross-height ratio less than 1 is satisfy the force transmission cap space truss model theory. The principal stress flow concentrated in the pile and column connections range like an olive. And the "olive" concrete can be considered an oblique bar in the cap of the column and the four common with the four top nodes. Principal tensile stress flow is between the two piles cap starting at the Department of a pile cap inside of the inside end of the pile to another. It can be seen as a cap at the bottom of the rod between the two piles. According this, the cross-section area formula of strut and tie in the internal oblique cap is raised. Through underpinning strip cap numerical analysis of strip foundation building, the force of two caps can meet space truss model theory, and the formula of oblique struts and tie is raised by the force transmission characteristics. Thus Design approach of underpinning cap is proposed. The stability of the steel pipe piles were studied by ANSYS Numerical analysis and experimental analysis. The buckling failure characteristics of steel pipe piles are obtained, and stability coefficientφand length factorμof steel pipe piles is checking. Through spreadsheets, stability coefficientφis between 0.7-0.9, length factorμis between 0.5-0.7. So the connection steel pipe pile is between the two ends of fixed and fixed the end of the hinge at one end between.By a 6-floor brick building underpinning development of space engineering design, the formula and design methods of underpinning components are systematic described.