Prestress strengthening method for external cables of bridges and culverts of prefabricated frames in gradient change jacking process

Abstract

The invention discloses a prestress strengthening method for external cables of bridges and culverts of prefabricated frames in a gradient change jacking process. Before jacking, external cable prestress tensioning structures are installed on the prefabricated frames in advance so as to apply prestress to overcome the tension stress caused in the jacking process, thereby ensuring that the structures of the prefabricated frames can not be damaged due to fact that front ends, rear ends or middle parts are suspended. The prestress strengthening method for the external cables of the bridges and culverts of the prefabricated frames in the gradient change jacking process, disclosed by the invention, can be used for eliminating the damage of the tension stress generated on the walls of the prefabricated frames to the structures of the prefabricated frames when the prefabricated frames pass through gradient change points of gradient change slide ways in the gradient change jacking process.

Description

technical field [0001] The invention relates to a prefabricated frame reinforcement method, in particular to a method for prestressed reinforcement of cables outside the culvert of a prefabricated frame bridge with variable slope jacking. Background technique [0002] For the high culvert project passing under the railway, the construction plan adopts prefabrication in the working pit outside the railway subgrade, and then the overhead railway is jacked into place according to the design. [0003] After the off-line prefabrication of the main body of the prefabricated frame was completed, it was found that the actual elevation of the upstream drainage culvert did not match the design. In order to solve the problem of culvert drainage, it is necessary to lower the design elevation of the culvert in the railway-related section. After calculation, the elevation drops by 65cm. Since the prefabricated frame has been prefabricated according to the original design elevation, the j...

AI Technical Summary

Problems solved by technology

[0007] 2. Jacking start: see image 3 , ①The front end of the prefabricated frame is in a suspended state. As the prefabricated frame moves forward, the contact surface between the prefabricated frame and the slideway becomes smaller and smaller, and the slideway bears an increasing load per unit area from the self-weight of the prefabricated frame. Concentration, it is easy to cause damage to the slideway structure, and the jacking slideway needs to be reinforced; ②The front section of the prefabricated frame is in a suspended state. Under the action of gravity of the suspended section, it is equivalent to applying a variable torque to the prefabricated frame. "Up-slope point" is the clockwise twisting trend of the fulcrum, so that tensile stress appears on the top and bottom surfaces of the prefabricated frame, which may lead to the destruction of the prefabricated frame

[0011] 6. See Figure 7 , the prefabricated frame passes through the slope change point: ①One end of the prefabricated frame acts on the glideslope, and the other end acts on the slope, forming concentrated loads on the glideslope and the slope respectively, which is very easy to damage the slide and also easy to improve the prefabricated frame. Cause damage; ②The downward slope point is suspended in the air. Under the action of gravity, the bottom of the prefabricated frame bottom and the bottom of the roof are prone to form tensile stress and cause damage to the prefabricated frame.

When the jacking slideway is a variable slope slideway, such as Figure 10 shows that when the prefabricated frame 4 passes through the upslope point (such as image 3 and Figure 4 ), the prefabricated frame 4 rotates, the rear end tilts, and the direction of the force transmission rod 3 is not parallel to the axis of the prefabricated frame bridge culvert, so that the force transmission rod cannot transmit the oil jacking force to the end of the prefabricated frame bridge culvert well, and may even It also led to the loss of stability of the dowel members, making it impossible to continue the prefabricated frame jacking construction

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