Experimental And Theoretical Research On Mechanical Behaviors Of RC Circular Pipe

Because of frequent cracking and shift in RC circular pipes applied in the freeways presently, mechanical behaviors of RC circular pipes are deeply and systematically studied by means of theory and experiments. The following major contents are included.(l)The calculating methods of soil pressure above pipe, reaction of rigid support and internal forces in pipe wall relating to several codes at home and abroad, are compared and analyzed.(2)The tensile strength and compressive strength of inner and outer RC circular pipe walls are tested, which are made by centrifugal and automatical technics with once or twice shaping or made by artificial and upstanding technics. Reasonable results of tensile strength and compressive strength of inner and outer pipe wall made by centrifugal and automatical technics are put forward, and the revised factors of concrete strength are also proposed.(3)3-edge bearing tests are carried out on RC circular pipes, which are made by centrifugal and automatical technics with once or twice shaping , or made by artificial and upstanding technics. Mechanical behaviors of RC circular pipes, for example, capacity of resisting cracking, width of cracking, ultimate bearing capacity, failure mode, stress and strain of steel and concrete, and radial displacement, are measured during full loading range. Furthermore, these mechanical behaviors are also theoretically analyzed and evaluated.(4)Regarding RC circular pipe and the soil around as a integral structure, and considering the interaction of soil and structure, the elastic and static finite element analysis is conducted by use of the finite element program-ANSYS. Based on field test and analysis, the earth pressure is analyzed with equal area equivalent method, and coefficients of vertical and horizontal earth pressure are put forward. Internal force calculating model of RC circular pipe under the action of soil fillings and vehicle loading is established, and reasonable calculating formulas of internal force and additional earth pressure caused by vehicle loading are presented.(5)Considering the interaction of soil and structure, major factors of affecting buried type of RC circular pipes' static mechanical behaviors are analyzed by use ofthe finite element program-ANSYS. Reasonable construction method of soil foundation under pipes, reasonable pattern and dimension of concrete support, and reducing load method of pipes' peripheral earth pressure under high soil fillings are put forward.